''Ctenolepisma longicaudatum'', generally known as the gray silverfish, long-tailed silverfish or paper silverfish, is a species of

Zygentoma Zygentoma are an order in the class Insecta, and consist of about 550 known species. The Zygentoma include the so-called silverfish or fishmoths, and the firebrats. A conspicuous feature of the order are the three long caudal filaments. The two ...

in the family

Lepismatidae Lepismatidae is a family of primitive wingless insects with about 190 described species. This family contains the two most familiar members of the order Zygentoma: the silverfish (''Lepisma saccharinum'') and the firebrat (''Thermobia domestica'' ...

. It was described by the German

entomologist Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as arach ...

Karl Leopold Escherich in 1905 based on specimens collected in

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

, but is found worldwide as

synanthrope A synanthrope (from the Greek σύν ''syn'', "together with" + ἄνθρωπος ''anthropos'', "man") is a member of a species of wild animal or plant that lives near, and benefits from, an association with human beings and the somewhat artific ...

in human housings. In recent years, gray silverfish have increasingly become an issue in indoor environments in Europe, especially in newly built houses with a stable climate beneficial for the growth and reproduction of this species. As a food

generalist A generalist is a person with a wide array of knowledge on a variety of subjects, useful or not. It may also refer to: Occupations * a physician who provides general health care, as opposed to a medical specialist; see also: ** General pract ...

with the ability to digest the

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

contained in paper and cellulose-based textiles like

rayon Rayon is a semi-synthetic fiber, made from natural sources of regenerated cellulose, such as wood and related agricultural products. It has the same molecular structure as cellulose. It is also called viscose. Many types and grades of viscose f ...

, ''Ctenolepisma longicaudatum'' is considered a

pest species A pest is any animal or plant harmful to humans or human concerns. The term is particularly used for creatures that damage crops, livestock, and forestry or cause a nuisance to people, especially in their homes. Humans have modified the environ ...

in cultural heritage institutions like libraries and archives.

Nomenclature

Most authors have historically treated the nomenclatural gender of ''Ctenolepisma'' as feminine, but in 2018 the

International Commission on Zoological Nomenclature The International Commission on Zoological Nomenclature (ICZN) is an organization dedicated to "achieving stability and sense in the scientific naming of animals". Founded in 1895, it currently comprises 26 commissioners from 20 countries. Orga ...

issued a formal ruling (ICZN Opinion 2427) stating the gender of ''Lepisma'' (and all genera with that ending) is neuter, following ICZN Article 30, which resulted in changes to the spelling of several well-known species, including ''Ctenolepisma longicaudatum'' (formerly ''longicaudata'').

Description

The

nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typ ...

and adults are slender, agile, fast-moving insects with long, paired antennae and three long appendages at the posterior abdomen: a pair of cerci and the single central

epiproct This glossary of entomology describes terms used in the formal study of insect species by entomologists. A–C A synthetic chlorinated hydrocarbon insecticide, toxic to vertebrates. Though i ...

. Apart from the earlies

instar An instar (, from the Latin '' īnstar'', "form", "likeness") is a developmental stage of arthropods, such as insects, between each moult (''ecdysis''), until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or ass ...

s, the body is covered with scales, giving the light- to dark greyish animals a glimmering appearance. With their brushes and bristles along the body sides, gray silverfish somewhat resemble the related

firebrat The firebrat (''Thermobia domestica'') is a small hexapod (typically 1–1.5 cm), in the order Zygentoma. Habitat Firebrats prefer higher temperatures and require some humidity, and can be found in bakeries and near boilers or f ...

s. The eyes consist of twelve

stemmata A simple eye (sometimes called a pigment pit) refers to a form of eye or an optical arrangement composed of a single lens and without an elaborate retina such as occurs in most vertebrates. In this sense "simple eye" is distinct from a multi-l ...

, which are rather more rounded in early instars.

Developmental stages

The eggs have an oval shape with dimensions of about 1.15 x 0.83 mm. Two to twenty eggs are laid per lot, and they are normally deposited about 2 mm into crevices or cracks, or under the edge of paper. Freshly laid eggs are smooth and cream-coloured; after three days the

chorion The chorion is the outermost fetal membrane around the embryo in mammals, birds and reptiles (amniotes). It develops from an outer fold on the surface of the yolk sac, which lies outside the zona pellucida (in mammals), known as the vitelline ...

turns yellow and exhibits shallow reticulate markings. First instar nymphs have a special hatching organ on the

frons Insect morphology is the study and description of the physical form of insects. The terminology used to describe insects is similar to that used for other arthropods due to their shared evolutionary history. Three physical features separate insec ...

of the head that helps them break free from the egg shell; this organ is shed with the first moulting. The air-filled crop pulsates vigorously in the hatching process, which takes about five minutes. The hatched first instar nymphs have a pale cream body colour and lack hairs and scales, the appendages are short and soft, and the anus seems to be closed. The 2nd instar nymphs exhibit a firmer, darker cream sclerotisation, and the longer appendages can be freely vibrated. A few bristles mark the position where the “brushes“ of the mature stages will be. This number of bristles increases with subsequent moultings, and the bristle pattern might be indicative for each instar. The 3rd, very active instar shows the body colour pattern of the succeeding instars: a dark cream colour with the edges of the thoracic

terga A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'ma ...

and the anal lobes tinted purple. The first three instars also have an increasing number of tarsal segments, by which they can be distinguished: the 1st instar has legs with two tarsal segments, whereas the 2nd instar exhibits three-segmented tarsi on the metathoracic pair of legs. The 3rd instar exhibits the three-segmented tarsi of all following stages. In the 4th instar, the first pair of styli appears on the ninth abdominal

sternum The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sh ...

, as well as the scales covering the body. Instars five to seven exhibit no particular distinguishing characters. In the 9th instar, the second pair of styli appears on the eighth abdominal segment in males; in female, these appear in the 11th instar. The genitalia first appear in the 8th nymphal instar, developing from two small lobes on the intersegmental membrane at the base of the cleft in the ninth sternum. The shape of this cleft, which first appears in the second instar and becomes more pronounced until the eighth instar, allows the distinction of the sex. A small cleft in the female's eighth sternum, which develops in early instars and completely divides this sternum in later instars, further facilitates sex determination. The genitalia lobes remain short in males until the shape of the penis can be distinguished in the 11th nymphal instar, when the internal reproductive organs will also have developed, including seven large testicles. The two short

vasa deferentia The vas deferens or ductus deferens is part of the male reproductive system of many vertebrates. The ducts transport sperm from the epididymis to the ejaculatory ducts in anticipation of ejaculation. The vas deferens is a partially coiled tube w ...

, which fuse immediately anterior to the penis, are thin-walled and slightly dilated at their distal ends; they lengthen in the next instar and form two loops between the two cercal nerves. The seminal vesicles form in the 13th instar, when also the penis reaches is final adult form by the ventral fusing of its rolled edges. In comparison to males, the female's genitalia lobes elongate in succeeding moultings. In the 10th nymphal instar, a second, anterior pair of lobes develops from the intersegmental membrane between abdominal segments 8 and 9 and extends to the ninth sternum's cleft in the 11th instar. In the following 12th instar, both pairs of genitalia lobes are almost of equal length. In the 13th instar, the

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

of the adults is formed by fusion and interlocking of the posterior lobes with the anterior ones. The complete ovipositor extends circa 1.2 mm beyond the sternum. The

spermatheca The spermatheca (pronounced plural: spermathecae ), also called receptaculum seminis (plural: receptacula seminis), is an organ of the female reproductive tract in insects, e.g. ants, bees, some molluscs, oligochaeta worms and certain other ...

first appears in the 10th instar as a short lobe directed anteriorly from the gonophyses. In the 12th instar the two side sacs and the central neck are still thin-walled and rather undifferentiated, whereas in the following 13th instar, well-marked, soft walls have formed. The internal reproductive organs are developed until the 13th instar, although the accessory glands and the "yellow" glands still lack pigmentation and the

ovariole An ovariole is a tubular component of the insect ovary, and the basic unit of egg production. Each ovariole is composed of a germarium (the germline stem cell niche) at the anterior tip, a set of developing oocytes contained within follicles, and ...

s contain not yet differentiated ova. From the 14th instar on, no further development apart from a gradual increase in size takes place. At 24 °C, eggs hatch after 34 days, and nymphs develop to the 13th instar within 11 months, with sexual maturity probably reached at 18 months of age. Gray silverfish can reach ages of about eight years, and unlike the hemi- and

holometabolous Holometabolism, also called complete metamorphosis, is a form of insect development which includes four life stages: egg, larva, pupa, and imago (or adult). Holometabolism is a synapomorphic trait of all insects in the superorder Endopterygot ...

insects, the

ametabolous The name Apterygota is sometimes applied to a subclass of small, agile insects, distinguished from other insects by their lack of wings in the present and in their evolutionary history; notable examples are the silverfish, the firebrat, and the ...

silverfish undergo further

moulting In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...

s even as imagines, with three to five moults per year.

Digestive tract

Gray silverfish have a simple digestive tract, consisting of a

hypopharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its struct ...

, a large, thin-walled

crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponic ...

(with the same pH as the ingested food) that occupies more than half of the body length, followed by the toothed

gizzard The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (pterosaurs, crocodiles, alligators, dinosaurs, birds), earthworms, some gastropods, so ...

, the mid-intestine, anteriorly (pH 4.8–5.4) with sacculi and further posteriad (pH 6.4–7.0) with a

peritrophic membrane The peritrophic matrix (from the prefix ''peri-'', meaning around, and ''-trophic'', referring to nutrition(food)) or peritrophic membrane is a semi-permeable, non-cellular structure which surrounds the food bolus in an organism's midgut. Although ...

enclosing the ingested food mass, the hind intestine (pH 2.6–3.8) with an anterior dorsal loop and ending in the rectum, with the anus being surrounded by two rows of papillae. The anterior region of the midgut exhibits gastric caeca, bladder-like extensions that absorb the nutrients of the digested food.

Histologically Histology, also known as microscopic anatomy or microanatomy, is the branch of biology Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single ...

, the midgut

epithelium Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...

consists of a single layer of columnar cells that border the midgut lumen with a

brush border A brush border (striated border or brush border membrane) is the microvilli-covered surface of simple cuboidal and simple columnar epithelium found in different parts of the body. Microvilli are approximately 100 nanometers in diameter and the ...

membrane. Interspersed in the midgut epithelium are nests of

stem cell In multicellular organisms, stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type o ...

s. The surface of hind intestine and rectum is greatly increased by deep longitudinal folds, presumably extracting water from the faeces. The hypopharynx is flanked by a pair of large

salivary gland The salivary glands in mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands (parotid, submandibular, and sublingual), as well as hundreds of minor salivary glands. Salivary gla ...

s which open into its lumen. The mid-intestinal cells of early instars are already as differentiated as in mature stages, and the gizzard is of the same form, although with fewer serrations and hairs on the teeth. The

malpighian tubules The Malpighian tubule system is a type of excretory and osmoregulatory system found in some insects, myriapods, arachnids and tardigrades. The system consists of branching tubules extending from the alimentary canal that absorbs solutes, water, ...

are relatively large until approximately the twelfth larval instar.

Biology

Diet

''Ctenolepisma longicaudatum'' is a

in human housings, and its natural food sources are unknown so that information on the biology of this species comes from indoor observations and rearings. Gray silverfish feed on a wide spectrum of substrates, ranging from plant remains like dried grass over insect remains to bread crumbs, paper, and artificial silk and cotton fabrics. They also eat cast skins from previous moults, as they prove rich in nutrients, containing 1% of the fat and 6% of the nitrogen stored in the body. Gray silverfish will not feed on wool felt, flannel, carpet, fur felt and natural silk. Paper made from

mechanical pulp Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw mate ...

is not attacked, and that from

Kraft The second incarnation of Kraft Foods is an American food manufacturing and processing conglomerate, split from Kraft Foods Inc. in 2012 and headquartered in Chicago, Illinois. It became part of Kraft Heinz in 2015. A merger with Heinz, arra ...

and

Esparto Esparto, halfah grass, or esparto grass is a fiber produced from two species of perennial grasses of north Africa, Spain and Portugal. It is used for crafts, such as cords, basketry, and espadrilles. ''Stipa tenacissima'' and ''Lygeum spartum ...

pulps is slightly attacked; only paper produced from ( bleached or unbleached) sulphite pulps is readily eaten. Paper consisting of 80% sulphite pulp and 20% mechanical pulp greatly reduces the attack by gray silverfish as compared to 100% sulphite pulp paper. Papers with 45% or more of mechanical pulp content are not attacked. Starvation experiments showed that gray silverfish can survive without food for up to around 250 to 300 days. While Lindsay (1940) states that gray silverfish do not actively take up (i.e., drink) water, but obtain it from the ingested food and from

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

of food, Heep (1967) shows that free, dyed water is taken up into the gut by dehydrated gray silverfish. Dehydrated ''C. longicaudatum'' are able to replenish their body water content from the water vapour in air of 60 to 100%

relative humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depe ...

Rearing

For rearing purposes, gray silverfish nymphs and adults can be fed on tissue paper, gummed paper, artificial silk, ground whole wheat and yeast, or oat flakes. The related firebrat, ''

Thermobia domestica The firebrat (''Thermobia domestica'') is a small hexapod (typically 1–1.5 cm), in the order Zygentoma. Habitat Firebrats prefer higher temperatures and require some humidity, and can be found in bakeries and near boilers or fu ...

'', can be fed whole wheat or plain flour; thoroughly dried and pulverised meat can be used as a strong attractant. In a dry environment, gray silverfish will die within one month, therefore a high humidity of 70–85% must be maintained under rearing conditions, e.g. through open containers of water next to the rearing containers. In addition, a moist cotton wick or a shallow tray of sand that has to be kept always damp might be provided in the rearing containers. The cultivation temperature should be around 24 °C. For egg deposition under rearing conditions, cotton wool can be provided. Since silverfish are

nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...

and photonegative, the light regime for a successful culture should be kept in favour of darkness, e.g. eight hours of light and 16 hours of darkness.

Reproduction

Reproduction is slow, as gray silverfish reach sexual maturity at the age of two to three years. They will reproduce for at least three years. The related firebrat reproduces only once a year and in irregular intervals.

Attractants

In the past it was assumed that gray silverfish use a contact pheromone for aggregation and arrestment, and that the aggregation

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

of the Lepismatidae species ''

Lepisma saccharinum The silverfish (''Lepisma saccharinum'') is a species of small, primitive, wingless insect in the order Zygentoma (formerly Thysanura). Its common name derives from the insect's silvery light grey colour, combined with the fish-like appearanc ...

'' (common silverfish) and ''Thermobia domestica'' (firebrat) has the same effect on the gray silverfish. Later research, first conducted on the firebrat ''Thermobia domestica'', indicated that aggregation behaviour is not triggered by pheromones, but by an endosymbiotic fungus, '' Mycotypha microspora'' ( Mycotyphaceae), and an endosymbiotic bacterium, ''

Enterobacter cloacae ''Enterobacter cloacae'' is a clinically significant Gram-negative, facultatively-anaerobic, rod-shaped bacterium. Microbiology In microbiology labs, ''E. cloacae'' is frequently grown at 30 °C on nutrient agar or at 35 °C in tr ...

'' (

Enterobacteriaceae Enterobacteriaceae is a large family (biology), family of Gram-negative bacteria. It was first proposed by Rahn in 1936, and now includes over 30 genera and more than 100 species. Its classification above the level of family is still a subject ...

), which are present in the faeces. It was also shown that firebrats detect the presence of ''E. cloacae'' based on its external

glycocalyx The glycocalyx, also known as the pericellular matrix, is a glycoprotein and glycolipid covering that surrounds the cell membranes of bacteria, epithelial cells, and other cells. In 1970, Martinez-Palomo discovered the cell coating in animal cells ...

polysaccharide Polysaccharides (), or polycarbohydrates, are the most abundant carbohydrates found in food. They are long chain polymeric carbohydrates composed of monosaccharide units bound together by glycosidic linkages. This carbohydrate can react with wa ...

s, most likely based on its D-

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...

component. ''Mycotypha microspora'' is only detected by firebrats in the presence of

, suggesting that metabolites of the enzymatic cellulose digestion by ''M. microspora'' (such as D-glucose) serves as the aggregation/arrestment cue. In a follow-up study, it was shown that gray silverfish also respond with arrestment to ''Mycotypha microspora''.

Natural enemies

Two species of ''Ctenolepisma'' are known to be parasitised by

Strepsiptera The Strepsiptera are an order of insects with eleven extant families that include about 600 described species. They are endoparasites in other insects, such as bees, wasps, leafhoppers, silverfish, and cockroaches. Females of most species never ...

: '' C. ciliatum'' is parasitised by '' Mengenilla chobauti'', and '' C. michaelseni'' by '' Mengenilla parvula''. It is not known as of yet, whether the gray silverfish is also parasitised by '' Mengenilla'' or other strepsipterans. Two species of

gregarine The gregarines are a group of Apicomplexan alveolates, classified as the Gregarinasina or Gregarinia. The large (roughly half a millimeter) parasites inhabit the intestines of many invertebrates. They are not found in any vertebrates. However, gr ...

parasites are recorded from the intestinal tract of the gray silverfish: ''Garnhamia aciculata'' and ''Lepismatophila ctenolepismae''. The related ''

Ctenolepisma lineatum ''Ctenolepisma lineatum'' is a species of insect of the order Zygentoma. It is generally similar to the closely related silverfish but can be distinguished by being rather stouter and less shiny with all appendages ( antennae and 3 "tails") not ...

'' contains on average 15 specimens of parasitic

Apicomplexa The Apicomplexa (also called Apicomplexia) are a large phylum of parasitic alveolates. Most of them possess a unique form of organelle that comprises a type of non-photosynthetic plastid called an apicoplast, and an apical complex structure. T ...

per animal in their intestinal tract, especially the crop. The spitting spider ''

Scytodes thoracica ''Scytodes thoracica'' is a spitting spider, so called because it spits a venomous sticky silken substance over its prey. Its size ranges between . The carapace is unusual in sloping upwards towards its rear end, whereas the abdomen slopes downwar ...

'' preys on

like the gray silverfish.

Distribution

The natural distribution of the gray silverfish is unknown, since all observations are from within or near human dwellings. The gray silverfish is recorded from the following

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

an countries: *

Albania Albania ( ; sq, Shqipëri or ), or , also or . officially the Republic of Albania ( sq, Republika e Shqipërisë), is a country in Southeastern Europe. It is located on the Adriatic and Ionian Seas within the Mediterranean Sea and shares ...

Austria Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...

: first record from a museum depot in

Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...

in 2002 *

Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...

: oldest record from 1998 *

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Macedon ...

Cyprus Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is geo ...

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

: first record from 2017 *

Denmark ) , song = ( en, "King Christian stood by the lofty mast") , song_type = National and royal anthem , image_map = EU-Denmark.svg , map_caption = , subdivision_type = Sovereign state , subdivision_name = Danish Realm, Kingdom of Denmark ...

: first record in 2017 *

Faroe Islands The Faroe Islands ( ), or simply the Faroes ( fo, Føroyar ; da, Færøerne ), are a North Atlantic island group and an autonomous territory of the Kingdom of Denmark. They are located north-northwest of Scotland, and about halfway bet ...

: recorded in 2017 *

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of B ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

: oldest record from

Hamburg (male), (female) en, Hamburger(s), Hamburgian(s) , timezone1 = Central (CET) , utc_offset1 = +1 , timezone1_DST = Central (CEST) , utc_offset1_DST = +2 , postal ...

in 1906, where live specimens were intercepted from ''

Echinocactus ''Echinocactus'' is a genus of cacti in the subfamily Cactoideae. The generic name derives from the Ancient Greek εχινος (''echinos''), meaning "spiny," and ''cactus''. It and ''Ferocactus'' are the two genera of barrel cactus. Members of ...

'' plants imported from

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders with ...

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...

: first record 1908 from Italy as misidentification ''C. ciliatum'' var. ''dives'' *

Lithuania Lithuania (; lt, Lietuva ), officially the Republic of Lithuania ( lt, Lietuvos Respublika, links=no ), is a country in the Baltic region of Europe. It is one of three Baltic states and lies on the eastern shore of the Baltic Sea. Lithuania ...

Luxembourg Luxembourg ( ; lb, Lëtzebuerg ; french: link=no, Luxembourg; german: link=no, Luxemburg), officially the Grand Duchy of Luxembourg, ; french: link=no, Grand-Duché de Luxembourg ; german: link=no, Großherzogtum Luxemburg is a small lan ...

Malta Malta ( , , ), officially the Republic of Malta ( mt, Repubblika ta' Malta ), is an island country in the Mediterranean Sea. It consists of an archipelago, between Italy and Libya, and is often considered a part of Southern Europe. It lies ...

Netherlands ) , anthem = ( en, "William of Nassau") , image_map = , map_caption = , subdivision_type = Sovereign state , subdivision_name = Kingdom of the Netherlands , established_title = Before independence , established_date = Spanish Netherl ...

: oldest record from 1989 *

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

: oldest confirmed records 1979 from the Zoological Museum of Oslo, and 2006 from

Bærum Bærum () is a municipality in the Greater Oslo Region in Norway that forms an affluent suburb of Oslo on the west coast of the city. Bærum is Norway's fifth largest municipality with a population of 128,760 (2021). It is part of the electoral ...

, officially registered for the country in 2014 *

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

Slovakia Slovakia (; sk, Slovensko ), officially the Slovak Republic ( sk, Slovenská republika, links=no ), is a landlocked country in Central Europe. It is bordered by Poland to the north, Ukraine to the east, Hungary to the south, Austria to the s ...

Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, an ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

: present since 1994 *

Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are installed in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel ...

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

: record from 2014

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

n countries with records of the gray silverfish: *

Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label=Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalahar ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...

Malawi Malawi (; or aláwi Tumbuka: ''Malaŵi''), officially the Republic of Malawi, is a landlocked country in Southeastern Africa that was formerly known as Nyasaland. It is bordered by Zambia to the west, Tanzania to the north and northeast ...

: oldest record from

Blantyre Blantyre () is Malawi's centre of finance and commerce, and its second largest city, with an enumerated 800,264 inhabitants . It is sometimes referred to as the commercial and industrial capital of Malawi as opposed to the political capital, L ...

in 1908 *

Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...

Mozambique Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi ...

: oldest record from Beira in 1912 *

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

: oldest record from 1933 *

Seychelles Seychelles (, ; ), officially the Republic of Seychelles (french: link=no, République des Seychelles; Creole: ''La Repiblik Sesel''), is an archipelagic state consisting of 115 islands in the Indian Ocean. Its capital and largest city, V ...

: first record 1905 from

Bothaville Bothaville is a maize farming town situated near the Vaal River in the Lejweleputswa District Municipality, Lejweleputswa DM of the Free State (South African province), Free State province, South Africa. It is situated 60 km east of the Vaal, ...

, the type locality of the gray silverfish *

Zimbabwe Zimbabwe (), officially the Republic of Zimbabwe, is a landlocked country located in Southeast Africa, between the Zambezi and Limpopo Rivers, bordered by South Africa to the south, Botswana to the south-west, Zambia to the north, and Mozam ...

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

countries and regions with records of the gray silverfish: *

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

: oldest record from Santos in 1908 *

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

Cuba Cuba ( , ), officially the Republic of Cuba ( es, República de Cuba, links=no ), is an island country comprising the island of Cuba, as well as Isla de la Juventud and several minor archipelagos. Cuba is located where the northern Caribbea ...

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...

El Salvador El Salvador (; , meaning " The Saviour"), officially the Republic of El Salvador ( es, República de El Salvador), is a country in Central America. It is bordered on the northeast by Honduras, on the northwest by Guatemala, and on the south b ...

Panama Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...

: oldest record from

Callao Callao () is a Peruvian seaside city and Regions of Peru, region on the Pacific Ocean in the Lima metropolitan area. Callao is Peru's chief seaport and home to its main airport, Jorge Chávez International Airport. Callao municipality consists o ...

in 1908 *

Puerto Rico Puerto Rico (; abbreviated PR; tnq, Boriken, ''Borinquen''), officially the Commonwealth of Puerto Rico ( es, link=yes, Estado Libre Asociado de Puerto Rico, lit=Free Associated State of Puerto Rico), is a Caribbean island and Unincorporated ...

Trinidad and Tobago Trinidad and Tobago (, ), officially the Republic of Trinidad and Tobago, is the southernmost island country in the Caribbean. Consisting of the main islands Trinidad and Tobago, and numerous much smaller islands, it is situated south of ...

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

North Carolina North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

, southern

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

(first(?) record 1955 from Pacific Beach)

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

n countries and regions with records of the gray silverfish: *

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...

Armenia Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ''Ox ...

Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China ( abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delt ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

Lebanon Lebanon ( , ar, لُبْنَان, translit=lubnān, ), officially the Republic of Lebanon () or the Lebanese Republic, is a country in Western Asia. It is located between Syria to the north and east and Israel to the south, while Cyprus li ...

Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...

Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...

Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...

Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...

Oceania Oceania (, , ) is a region, geographical region that includes Australasia, Melanesia, Micronesia, and Polynesia. Spanning the Eastern Hemisphere, Eastern and Western Hemisphere, Western hemispheres, Oceania is estimated to have a land area of ...

n countries with records of the gray silverfish: *

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

: oldest record from 1905 *

New Caledonia ) , anthem = "" , image_map = New Caledonia on the globe (small islands magnified) (Polynesia centered).svg , map_alt = Location of New Caledonia , map_caption = Location of New Caledonia , mapsize = 290px , subdivision_type = Sovereign st ...

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

Vanuatu Vanuatu ( or ; ), officially the Republic of Vanuatu (french: link=no, République de Vanuatu; bi, Ripablik blong Vanuatu), is an island country located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is east of no ...

Damage of cellulose-based materials

The gray silverfish is able to feed on paper and similar materials comprising

. In a comparative screening for cellulolytic activity, the gray silverfish was found to have the highest relative cellulase activity, by far exceeding that of other cellulose-digesting insects like '' Conocephalus strictus'' (

Orthoptera Orthoptera () is an order of insects that comprises the grasshoppers, locusts, and crickets, including closely related insects, such as the bush crickets or katydids and wētā. The order is subdivided into two suborders: Caelifera – grassho ...

), the termite ''

Reticulitermes flavipes ''Reticulitermes flavipes'', the eastern subterranean termite, is the most common termite found in North America. These termites are the most economically important wood destroying insects in the United States and are classified as pests. They fe ...

'' (

Blattodea Blattodea is an order of insects that contains cockroaches and termites. Formerly, termites were considered a separate order, Isoptera, but genetic and molecular evidence suggests they evolved from within the cockroach lineage, cladistically ...

Rhinotermitidae Rhinotermitidae is a family of termites (Isoptera). They feed on wood and can cause extensive damage to buildings or other wooden structures. About 345 species are recognized, among these are severe pests such as '' Coptotermes formosanus'', ''Co ...

), ''

Cryptocercus ''Cryptocercus'' is a genus of Dictyoptera (cockroaches and allies) and the sole member of its own family Cryptocercidae. Species are known as wood roaches or brown-hooded cockroaches. These roaches are subsocial, their young requiring considera ...

'' roaches (Blattodea:

Cryptocercidae ''Cryptocercus'' is a genus of Dictyoptera (cockroaches and allies) and the sole member of its own family Cryptocercidae. Species are known as wood roaches or brown-hooded cockroaches. These roaches are subsocial, their young requiring considera ...

) and

Scolytinae A bark beetle is the common name for the subfamily of beetles Scolytinae. Previously, this was considered a distinct family (Scolytidae), but is now understood to be a specialized clade of the "true weevil" family (Curculionidae). Although the ...

bark beetles (

Coleoptera Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 describ ...

). The highest activity of plant cell wall degrading enzymes is found in the head and especially in the foregut of the gray silverfish.

Endoglucanase Cellulase (EC 3.2.1.4; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharide ...

, which breaks down the cellulose chain into smaller fragments, is found in both the head and foregut part of the digestive tract, whereas

β-glucosidase β-Glucosidase (EC 3.2.1.21; systematic name β-D-glucoside glucohydrolase) is an enzyme that catalyses the following reaction: : Hydrolysis of terminal, non-reducing β-D-glucosyl residues with release of β-D-glucose Structure β-Glucosidase ...

, which catalyses the final degradation into

, is present in the foregut, but not in the head tissue; β-xylosidase activity is very low in the head, but the enzyme is present in the foregut.

Polygalacturonase Endo-polygalacturonase (EC 3.2.1.15, pectin depolymerase, pectolase, pectin hydrolase, and poly-α-1,4-galacturonide glycanohydrolase; systematic name (1→4)-α-D-galacturonan glycanohydrolase (endo-cleaving)) is an enzyme that hydrolyzes the α- ...

activity is not observed in ''C. longicaudatum''. A cellulose-rich diet does not increase the cellulase activity, suggesting that the production of these cellulolytic enzymes is not diet-regulated. Although a mixed diet is necessary for the natural development of ''C. longicaudatum'', it can survive more than 600 days on a diet of cellulose alone. As such, the gray silverfish is a threat to

cultural heritage Cultural heritage is the heritage of tangible and intangible heritage assets of a group or society that is inherited from past generations. Not all heritages of past generations are "heritage"; rather, heritage is a product of selection by soci ...

institutions storing books, sheet music, paintings and similar objects. A Swedish survey on the damage impact of ''C. longicaudatum'' reports attacks on: watercolor paintings; packing material; cartons; books, where the outer cover, glued areas inside of the cover and marbled paper were eaten; historical documents of handmade paper; paper documents; transcripts; stamps in showrooms; newly produced signs labels in showrooms; historical paper labels on objects; mounting paper on the back of a photograph; roll painting in genuine

silk Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the coc ...

, mounted with

starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human diets ...

paste on

masonite Masonite is a type of hardboard, a kind of engineered wood, which is made of steam-cooked and pressure-molded wood fibers in a process patented by William H. Mason. It is also called Quartrboard, Isorel, hernit, karlit, torex, treetex, and pr ...

; insects caught in adhesive traps.

Control measurements

In recent years, gray silverfish have been reported from a number of European countries (see section

Distribution Distribution may refer to: Mathematics *Distribution (mathematics), generalized functions used to formulate solutions of partial differential equations * Probability distribution, the probability of a particular value or value range of a vari ...

), where they have been recorded as a nuisance pest in houses, kindergartens and schools, but also as damaging cellulose-based materials in a warehouse and in cultural heritage institutions like museums, libraries and archives. In

Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in northwestern Europe *Norwegians, both a nation and an ethnic group native to Norway *Demographics of Norway *The Norwegian language, including the ...

houses, the number of pest control measurements against the gray silverfish have drastically increased since the year 2016. The majority of insurance cases involving the gray silverfish apply to new houses built after the year 2000, which, due to the improved wall insulation, assumingly provide more favourable living conditions for this species. Due to their relatively slow development and longevity and their ability to survive up to ten months without food, control measurements against the gray silverfish have to be applied over an extended period of time. An

integrated pest management Integrated pest management (IPM), also known as integrated pest control (IPC) is a broad-based approach that integrates both chemical and non-chemical practices for economic control of pests. IPM aims to suppress pest populations below the econ ...

, applying several control measurements in parallel, has been proposed as the most promising approach for the control of this species. This includes the removal of potential food sources such as food crumbs by wiping the floor also beneath and behind cooking stoves and refrigerators, and storage of dried food products, including tea bags and animal food, in sealed containers. Reducing the amount of water used during cleaning will reduce indoor humidity, which is detrimental for egg development. It should also be kept in mind that gray silverfish do not have to drink, and can use the water vapour contained in air of 60% relative humidity and higher as their water source instead.

Trapping

A common control measurement is the use of sticky traps, especially for monitoring purposes to get an idea on the dimension of silverfish infestation. Adding milled

cricket Cricket is a bat-and-ball game played between two teams of eleven players on a field at the centre of which is a pitch with a wicket at each end, each comprising two bails balanced on three stumps. The batting side scores runs by striki ...

powder to sticky traps as protein-rich bait has been shown to result in a significantly higher average catch as compared to unbaited sticky traps.

Poisoning

Toxic baits are another means of reducing or eradicating silverfish infestation. Aak et al. (2020) tested different commercially available paste-based products, containing

imidacloprid Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. ...

clothianidin Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has be ...

fipronil Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. Fipronil disrupts the insect central nervous system by blocking the ligand-gated ion channel of the GABAA receptor and glutamate-gated chloride (GluCl ...

indoxacarb Indoxacarb is an oxadiazine pesticide developed by DuPont that acts against lepidopteran larvae. It is marketed under the names Indoxacarb Technical Insecticide, Steward Insecticide and Avaunt Insecticide. It is also used as the active ingredie ...

as active ingredient, regarding their effect in pest management of gray silverfish. Imidacloprid was found to cause a

mortality rate Mortality rate, or death rate, is a measure of the number of deaths (in general, or due to a specific cause) in a particular population, scaled to the size of that population, per unit of time. Mortality rate is typically expressed in units of de ...

of less than 50% after 18 days, whereas the other three pesticides caused mortality rates above 90%. Indoxacarb application in field trials decreased gray silverfish populations to less than 10% within 10 to 12 weeks. Since silverfish also consume dead insects, including specimens of their own species, secondary poisoning through the consumption of primarily poisoned individuals has an additional population-reducing effect. With 75% mortality, indoxacarb was found to be much more potent in secondary poisoning as compared to clothianidin with a 15% mortality rate. Indoxacarb was therefore evaluated as the most potent poison against gray silverfish, and even six-month old bait was still able to cause a high mortality rate. Fipronil as poison was not further investigated due to its comparatively high

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subst ...

for humans. When using toxic baits, attention should be paid to the secure placement of these baits to minimise the chance of unintentional ingestion by pets or children. Placing small droplets of gel-based poison into gaps, crevices and cracks that act as natural hiding places for silverfish during the day will reduce the likelihood of unintended contact and at the same time increase the chance of the poison being ingested by the gray silverfish. Distributing many small poison bait droplets, as opposed to few large portions, evenly over the infested area will further increase the success of the poison treatment. A study on the efficacy of various poisonous baits (containing

boric acid Boric acid, more specifically orthoboric acid, is a compound of boron, oxygen, and hydrogen with formula . It may also be called hydrogen borate or boracic acid. It is usually encountered as colorless crystals or a white powder, that dissolves ...

hydramethylnon Hydramethylnon is an organofluorine compound. It is also known as AC 217,300. It is in a chemical class called trifluoromethyl aminohydrazone, which is a metabolic inhibitor. It is classified as a pesticide designed to control insects that are ...

, indoxacarb,

abamectin Abamectin is a widely used insecticide and anthelmintic. Abamectin, is a member of the Avermectin family and is a natural fermentation product of soil dwelling actinomycete ''Streptomyces avermitilis''. Abamectin (also called Avermectin B1), differ ...

chlorfenapyr Chlorfenapyr is a pesticide, and specifically a pro-insecticide (meaning it is metabolized into an active insecticide after entering the host), derived from a class of microbially produced compounds known as halogenated pyrroles. History and App ...

dinotefuran Dinotefuran is an insecticide of the neonicotinoid class developed by Mitsui Chemicals for control of insect pests such as aphids, whiteflies, thrips, leafhoppers, leafminers, sawflies, mole cricket, white grubs, lacebugs, billbugs, beetles, m ...

, fipronil, metaflumizone, and

novaluron Novaluron, or (±)-1- -chloro-4-(1,1,2-trifluoro-2-trifluoro- methoxyethoxy)phenyl3-(2,6-difluorobenzoyl)urea, is a chemical with pesticide properties, belonging to the class of insecticides called insect growth regulators. It is a benzoylphenyl ...

) against the related Lepismatidae species ''

'' and ''

'' has been conducted by Sims & Appel (2012).

Pesticide spraying

Studies on the effects of pesticide sprays on ''Ctenolepisma longicaudatum'' have not been published. A study by Faulde et al. (2003) investigated the knockdown (i.e., inability to move, and lying upside down) effect of fabrics spray-impregnated with

permethrin Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto clothing or mosquito nets to kill the insects that t ...

on the related common silverfish (''Lepisma saccharinum''), where a 100% knockdown was observed after 5.5 ± 2.6 min of exposure to the permethrin coating. Since the premises inhabited by gray silverfish are usually co-inhabited by humans, the application of pesticides in the form of sprays should be avoided wherever possible, and more targeted approaches like bait poisoning should be considered. As pesticide-sprayed areas will be avoided by silverfish, a risk of their dispersal towards unaffected areas is given, which will prolong the pest management efforts.

Temperature treatment

At temperatures of 16 °C and below, the growth rate is considerably decreased, with an average length of adult stadia (i.e., the time between two consecutive mouldings) of 126 days as compared to 15 days at 29 °C. 16 °C can therefore be seen as limiting temperature for active feeding and growth.

Torpor Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables animals to survive periods of reduced food availability. The term "torpor" can refer to the time ...

sets in at a temperature of 13 °C, and at 11 °C,

ecdysis Ecdysis is the moulting of the cuticle in many invertebrates of the clade Ecdysozoa. Since the cuticle of these animals typically forms a largely inelastic exoskeleton, it is shed during growth and a new, larger covering is formed. The remna ...

stops. Nymphs are much more sensitive to cold: at a temperature of 1 °C, second instar larvae die within two days, whereas adult specimens can survive several months. At 21 °C, egg development takes on average 49 days, which decreases with higher temperatures; at 29.5 °C, hatching occurs after 20 days. At 21 °C, the first larval instar is on average 9 days long, which is reduced to 5 days at temperatures of 24 °C and above. Prolonged temperatures above 24 °C are eventually fatal for gray silverfish: At 26 °C, the survival is 4 months, and at temperatures of 29 to 33.6 °C, survival time drops to 1–3 weeks. Heeg (1967) found the optimum temperature range of the gray silverfish to be in the range of 8 to 25 °C, with the upper avoidance temperature at 40–43 °C. Survival rate at high temperatures is higher in dry air of 5%

(RH) as compared to 85% RH, presumably due to water

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

from the insects' bodies. However, prolonged exposure to such low humidity levels will lead to death within 2–4 weeks. A critical humidity value seems to be 55%, below which the period of survival is drastically reduced. These observations show that ambient temperature should be taken into account when applying an integrated pest management plan. If poisoned bait is used, temperatures should be at 20 °C or higher, as food is consumed much more rapidly as compared to 16 °C (at even lower temperatures, feeding comes to a halt). If the aim is to gain time to prepare control measures, a decrease in ambient temperature in the infested premises to 16 °C or lower is advisable to slow down population growth.

References

External links

* {{Taxonbar, from=Q3921111 Lepismatidae Articles created by Qbugbot Insects described in 1905

Nomenclature

Description

Developmental stages

Digestive tract

Biology

Diet

Rearing

Reproduction

Attractants

Natural enemies

Distribution

Damage of cellulose-based materials

Control measurements

Trapping

Poisoning

Pesticide spraying

Temperature treatment

References

Further reading

External links