Sawflies are the insects of the
suborder Symphyta within the order
Hymenoptera
Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...
, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of 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 ...
, which the females use to cut into the plants where they lay their eggs. The name is associated especially with the
Tenthredinoidea
The Tenthredinoidea are the dominant superfamily of sawflies within the Symphyta, containing some 8,400 species worldwide, primarily in the family Tenthredinidae. All known larvae are phytophagous, and a number are considered pests.
The include ...
, by far the largest
superfamily in the suborder, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera. Symphyta is
paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
, consisting of several
basal groups within the order Hymenoptera, each one rooted inside the previous group, ending with the
Apocrita
Apocrita is a suborder of insects in the order Hymenoptera. It includes wasps, bees, and ants, and consists of many families. It contains the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" ( petiole) formed ...
which are not sawflies.
The primary distinction between sawflies and the Apocrita – the ants, bees, and wasps – is that the adults lack a "wasp waist", and instead have a broad connection between the
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
and the
thorax
The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
. Some sawflies are
Batesian mimics of wasps and bees, and the ovipositor can be mistaken for a
stinger
A stinger (or sting) is a sharp organ found in various animals (typically insects and other arthropods) capable of injecting venom, usually by piercing the epidermis of another animal.
An insect sting is complicated by its introduction of ve ...
. Sawflies vary in length, most measuring ; the largest known sawfly measured . The larvae are caterpillar-like, but can be distinguished by the number of
proleg
A proleg is a small, fleshy, stub structure found on the ventral surface of the abdomen of most larval forms of insects of the order Lepidoptera, though they can also be found on other larval insects such as sawflies and a few other types of in ...
s and the absence of
crochets in sawfly larvae. The great majority of sawflies are
plant-eating, though the members of the superfamily
Orussoidea
Orussoidea is a superfamily of sawflies. It contains the living family Orussidae, as well as the extinct families Burmorussidae and Paroryssidae. They are the group of sawflies closest to the Apocrita, the group containing wasps, bees and ants, w ...
are
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
.
Predators include birds, insects and small animals. The larvae of some species have
anti-predator adaptation
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avo ...
s such as regurgitating irritating liquid and clustering together for safety in numbers. Saw flier are hosts to many parasitoids, most of which are Hymenoptera, the rest being
Diptera.
Adult sawflies are short-lived, with a life expectancy of 7–9 days, though the larval stage can last from months to years, depending on the species.
Parthenogenetic
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...
females, which do not need to mate to produce fertilised eggs, are common in the suborder, though many species have males. The adults feed on pollen, nectar, honeydew, sap, other insects, including hemolymph of the larvae hosts; they have mouth pieces adapted to these types of feeding.
Sawflies go throughly a
complete metamorphosis
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 Endopterygo ...
with four distinct life stages – egg, larva, pupa and adult. The female uses her ovipositor to drill into plant material (or, in the case of Orussoidea, other insects) and then lays eggs in groups called rafts or pods. After hatching, larvae feed on plants, often in groups. As they approach adulthood, the larvae seek a protected spot to pupate, typically in bark or the soil. Large populations of species such as the
pine sawfly
The Diprionidae are a small family of conifer
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division c ...
can cause substantial damage to economic
forestry
Forestry is the science and craft of creating, managing, planting, using, conserving and repairing forests, woodlands, and associated resources for human and environmental benefits. Forestry is practiced in plantations and natural stands. Th ...
, while others such as the
iris sawfly are major pests in
horticulture
Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
. Outbreaks of sawfly larvae can defoliate trees and may cause dieback, stunting or death. Sawflies can be controlled through the use of insecticides, natural predators and parade, or mechanical methods.
Sawflies first appeared 250 million years ago in the
Triassic
The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...
. The oldest superfamily, the
Xyeloidea
The Xyelidae are a comparatively species-poor family of sawflies comprising about 80 extant species in five genera worldwide and is the only family in the superfamily Xyeloidea. The fossil record of the family is extensive, comprising more than ...
, has existed into the presents. Over 200 million years ago, a lineage of sawflies evolved a parasitoid lifestyle, with carnivorous larvae that ate the eggs or larvae of other insects. Sawflies are distributed globally, though they are more diverse in the northernmost hemispheres
Etymology
The suborder name "Symphyta" derives from the Greek word ''symphyton'', meaning "grown together", referring to the group's distinctive lack of a wasp waist between prostomium and peristomium. Its common name, "sawfly", derives from the
saw
A saw is a tool consisting of a tough blade, wire, or chain with a hard toothed edge. It is used to cut through material, very often wood, though sometimes metal or stone. The cut is made by placing the toothed edge against the material and mov ...
-like ovipositor that is used for egg-laying, in which a female makes a slit in either a stem or plant leaf to deposit the eggs.
[ The first known use of this name was in 1773. Sawflies are also known as "wood-wasps".]
Phylogeny
In his original description of Hymenoptera
Hymenoptera is a large order (biology), order of insects, comprising the sawfly, sawflies, wasps, bees, and ants. Over 150,000 living species of Hymenoptera have been described, in addition to over 2,000 extinct ones. Many of the species are Par ...
in 1863, German zoologist Carl Gerstaecker divided them into three groups, ''Hymenoptera aculeata'', ''Hymenoptera apocrita'' and ''Hymenoptera phytophaga''. But four years later in 1867, he described just two groups, ''H. apocrita'' syn. ''genuina'' and ''H. symphyta'' syn. ''phytophaga''. Consequently, the name Symphyta is given to Gerstaecker as the zoological authority. In his description, Gerstaecker distinguished the two groups by the transfer of the first abdominal segment to the thorax in the Apocrita
Apocrita is a suborder of insects in the order Hymenoptera. It includes wasps, bees, and ants, and consists of many families. It contains the most advanced hymenopterans and is distinguished from Symphyta by the narrow "waist" ( petiole) formed ...
, compared to the Symphyta. Consequently, there are only eight dorsal half segments in the Apocrita, against nine in the Symphyta. The larvae are distinguished in a similar way.
The Symphyta have therefore traditionally been considered, alongside the Apocrita, to form one of two suborders of Hymenoptera. Symphyta are the more primitive group, with comparatively complete venation
Venation may refer to:
* Venation (botany), the arrangement of veins in leaves
* Wing venation, the arrangement of veins in insect wings
See also
*
* Vernation
Vernation (from ''vernal'' meaning ''spring'', since that is when leaves spring fort ...
, larvae that are largely phytophagous
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...
, and without a "wasp-waist", a symplesiomorphic feature. Together, the Symphyta make up less than 10% of hymenopteran species. While the terms sawfly and Symphyta have been used synonymously, the Symphyta have also been divided into three groups, true sawflies (phyllophaga), woodwasps
Horntail or wood wasp are any of the 150 non-social species of the hymenopteran family Siricidae, a type of xylophagous, wood-eating Symphyta, sawfly. The common name "horntail" derives from the stout, spine-like structure at the end of the adult ...
or xylophaga (Siricidae), and Orussidae
The Orussidae or the parasitic wood wasps represent a small family of sawflies (" Symphyta"). Currently, about 93 extant and four fossil species are known. They take a key position in phylogenetic analyses of Hymenoptera, because they form the s ...
. The three groupings have been distinguished by the true sawflies' ventral serrated or saw-like ovipositor for sawing holes in vegetation to deposit eggs, while the woodwasp ovipositor penetrates wood and the Orussidae behave as external parasitoids
In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasi ...
of wood-boring beetles. The woodwasps themselves are a paraphyletic
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
ancestral grade
Grade most commonly refers to:
* Grade (education), a measurement of a student's performance
* Grade, the number of the year a student has reached in a given educational stage
* Grade (slope), the steepness of a slope
Grade or grading may also ref ...
. Despite these limitations, the terms have utility and are common in the literature.
While most hymenopteran superfamilies are monophyletic
In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
, as is Hymenoptera, the Symphyta has long been seen to be paraphyletic. Cladistic
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived char ...
methods and molecular phylogenetics
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
are improving the understanding of relationships between the superfamilies, resulting in revisions at the level of superfamily and family. The Symphyta are the most primitive ( basal) taxa
In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
within the Hymenoptera (some going back 250 million years), and one of the taxa within the Symphyta gave rise to the monophyletic suborder Apocrita (wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
s, bees, and ant
Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from vespoid wasp ancestors in the Cretaceous period. More than 13,800 of an estimated total of ...
s). In cladistic analyses the Orussoidea are consistently the sister group to the Apocrita.
The oldest unambiguous sawfly fossils date back to the Middle or Late
Late may refer to:
* LATE, an acronym which could stand for:
** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia
** Local-authority trading enterprise, a New Zealand business law
** Local average treatment effect, ...
Triassic. These fossils, from the family Xyelidae
The Xyelidae are a comparatively species-poor family of sawflies comprising about 80 Extant taxon, extant species in five genera worldwide and is the only family in the superfamily Xyeloidea. The fossil record of the family is extensive, comprisi ...
, are the oldest of all Hymenoptera. One fossil, ''Archexyela ipswichensis'' from Queensland is between 205.6 and 221.5 million years of age, making it among the oldest of all sawfly fossils. More Xyelid fossils have been discovered from the Middle Jurassic and the Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
, but the family was less diverse then than during the Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
and Tertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
. The subfamily Xyelinae were plentiful during these time periods, in which Tertiary faunas were dominated by the tribe Xyelini; these are indicative of a humid and warm climate.
The cladogram is based on Schulmeister 2003.
Taxonomy
There are approximately 8,000 species of sawfly in more than 800 genera, although new species continue to be discovered. However, earlier studies indicated that 10,000 species grouped into about 1,000 genera were known. Early phylogenies
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
such as that of Alexandr Rasnitsyn
Alexandr Pavlovich Rasnitsyn (Russian: Александр Павлович Расницын) is a Russian entomologist, expert in palaeoentomology, and Honored Scientist of the Russian Federation (2001).
His scientific interests are centered on ...
, based on morphology and behaviour, identified nine clades
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
which did not reflect the historical superfamilies. Such classifications were replaced by those using molecular methods, starting with Dowton and Austin (1994). As of 2013, the Symphyta are treated as nine superfamilies (one extinct) and 25 families. Most sawflies belong to the Tenthredinoidea superfamily, with about 7,000 species worldwide. Tenthredinoidea has six families, of which Tenthredinidae
Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem ...
is by far the largest with some 5,500 species.
Extinct taxa are indicated by a dagger
A dagger is a fighting knife with a very sharp point and usually two sharp edges, typically designed or capable of being used as a thrusting or stabbing weapon.State v. Martin, 633 S.W.2d 80 (Mo. 1982): This is the dictionary or popular-use de ...
(†).
;Superfamilies and families
* Superfamily Anaxyeloidea
Anaxyelidae is a family of incense cedar wood wasps in the order Hymenoptera. It contains only one living genus, '' Syntexis'', which has only a single species, native to Western North America. Fossils of the family extend back to the Middle Jur ...
Martynov, 1925
** Family Anaxyelidae
Anaxyelidae is a family of incense cedar wood wasps in the order Hymenoptera. It contains only one living genus, '' Syntexis'', which has only a single species, native to Western North America. Fossils of the family extend back to the Middle Jura ...
Martynov, 1925 (1 species) & †12 genera
* Superfamily Cephoidea
Cephoidea is a small superfamily within the Symphyta, commonly referred to as stem sawflies, containing some 100 species in 10 genera in the living family, Cephidae, plus another 17 genera in the extinct family Sepulcidae. Most species occur ...
Newman, 1834 (1 & †1family)
** Family Cephidae
Cephidae is a family of stem sawflies in the order Hymenoptera. There are about 27 genera and more than 160 described species in Cephidae.
Genera
These 27 genera belong to the family Cephidae:
* '' Athetocephus'' Benson, 1935
* '' Australcep ...
Newman, 1834 (21 genera, 160 spp.
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate se ...
& †3 genera
* †Superfamily Karatavitoidea
Karatavitidae is an extinct family of sawflies, known from the Jurassic period, they are the only members of the superfamily Karatavitoidea. While once proposed to be grouped with the Orussoidea in the infraorder Orussomorpha, they are now consi ...
Rasnitsyn, 1963 (1 family)
* Superfamily Orussoidea
Orussoidea is a superfamily of sawflies. It contains the living family Orussidae, as well as the extinct families Burmorussidae and Paroryssidae. They are the group of sawflies closest to the Apocrita, the group containing wasps, bees and ants, w ...
Newman, 1834 (1 & †1 family)
** Family Orussidae
The Orussidae or the parasitic wood wasps represent a small family of sawflies (" Symphyta"). Currently, about 93 extant and four fossil species are known. They take a key position in phylogenetic analyses of Hymenoptera, because they form the s ...
Newman, 1834 (16 genera, 82 spp.) & †3 genera
* Superfamily Pamphilioidea
The Pamphilioidea are a small superfamily within the Symphyta (the sawflies), containing some 250 living species restricted to the temperate regions of Eurasia and North America. These hymenopterans share the distinctive feature of a very la ...
Cameron, 1890 (2 & †1 families) ( syn. Megalodontoidea)
** Family Megalodontesidae
The Megalodontesidae (until recently spelled Megalodontidae, a name already in use for a family of fossil molluscs) are a small family of sawflies, containing a single living genus, '' Megalodontes'', with some 40 species restricted to the temper ...
Konow, 1897 (1 genera, 42 spp.) & †1 genus
** Family Pamphiliidae
Pamphiliidae (sometimes incorrectly spelled Pamphilidae) is a small wasp family within Symphyta, containing some 200 species from the temperate regions of North America and Eurasia. The larvae feed on plants (often conifers), using silk to bu ...
Cameron, 1890 (10 genera, 291 spp.) & †3 genera
* Superfamily Siricoidea
The superfamily Siricoidea is an archaic group of the order Hymenoptera, consisting of six families (four extinct) of xylophagous sawflies. The group is well represented in early Tertiary and Mesozoic times, but a number of living taxa remain, inc ...
Billberg, 1820 (2 & †5 families)
** Family Siricidae Billberg, 1820 (11 genera, 111 spp.) & †9 genera
* Superfamily Tenthredinoidea
The Tenthredinoidea are the dominant superfamily of sawflies within the Symphyta, containing some 8,400 species worldwide, primarily in the family Tenthredinidae. All known larvae are phytophagous, and a number are considered pests.
The include ...
Latreille, 1803 (6 & †2 families)
** Family Argidae
Argidae is a large family of sawflies, containing some 800 species worldwide, primarily in tropical regions. The larvae are phytophagous, and commonly can be found feeding (and often pupating) in groups, though very few attain pest status.
The ...
Konow, 1890 (58 genera, 897 spp.) and †1 genus
** Family Blasticotomidae Thomson, 1871 (2 genera, 12 spp.) & †1 genus
** Family Cimbicidae W. Kirby, 1837 (16 genera, 182 spp.) & †6 genera
** Family Diprionidae
The Diprionidae are a small family of conifer-feeding sawflies (thus the common name conifer sawflies, though other Symphyta also feed on conifers) restricted to the Northern Hemisphere, with some 140 species in 13 genera. Larvae are often greg ...
Rohwer, 1910 (11 genera, 136 spp.) & †2 genera
** Family Pergidae Rohwer, 1911 (60 genera, 442 spp.)
** Family Tenthredinidae
Tenthredinidae is the largest family of sawflies, with well over 7,500 species worldwide, divided into 430 genera. Larvae are herbivores and typically feed on the foliage of trees and shrubs, with occasional exceptions that are leaf miners, stem ...
Latreille, 1803 (400 genera, 5,500 spp.) & †14 genera
* Superfamily Xiphydrioidea
Xiphydriidae are a family of wood wasps that includes around 150 species. They are located all over the world including North and South America, Australia, Europe, and others. Xiphydriidae larvae are wood borers in dead trees or branches of a ran ...
Leach, 1819
** Family Xiphydriidae
Xiphydriidae are a family of wood wasps that includes around 150 species. They are located all over the world including North and South America, Australia, Europe, and others. Xiphydriidae larvae are wood borers in dead trees or branches of a ran ...
Leach, 1819 (28 genera, 146 spp.)
* Superfamily Xyeloidea
The Xyelidae are a comparatively species-poor family of sawflies comprising about 80 extant species in five genera worldwide and is the only family in the superfamily Xyeloidea. The fossil record of the family is extensive, comprising more than ...
Newman, 1834
** Family Xyelidae
The Xyelidae are a comparatively species-poor family of sawflies comprising about 80 Extant taxon, extant species in five genera worldwide and is the only family in the superfamily Xyeloidea. The fossil record of the family is extensive, comprisi ...
Newman, 1834 (5 genera, 63 spp.) & †47genera
Description
Many species of sawfly have retained their ancestral attributes throughout time, specifically their plant-eating habits, wing veins and the unmodified abdomen, where the first two segments appear like the succeeding segments. The absence of the narrow wasp waist distinguishes sawflies from other members of hymenoptera, although some are Batesian mimics with coloration similar to wasps and bees, and the ovipositor can be mistaken for a stinger. Most sawflies are stubby and soft-bodied, and fly weakly. Sawflies vary in length: ''Urocerus gigas'', which can be mistaken as a wasp due to its black-and-yellow striped body, can grow up to in length, but among the largest sawflies ever discovered was '' Hoplitolyda duolunica'' from the Mesozoic, with a body length of and a wingspan of . The smaller species only reach lengths of .
Heads of sawflies vary in size, shape and sturdiness, as well as the positions of the eyes and antennae. They are characterised in four head types: open head, maxapontal head, closed head and genapontal head. The open head is simplistic, whereas all the other heads are derived. The head is also hypognathous, meaning that the lower mouthparts are directed downwards. When in use, the mouthparts may be directed forwards, but this is only caused when the sawfly swings its entire head forward in a pendulum motion. Unlike most primitive insects, the sutures (rigid joints between two or more hard elements on an organism) and sclerite
A sclerite (Greek , ', meaning " hard") is a hardened body part. In various branches of biology the term is applied to various structures, but not as a rule to vertebrate anatomical features such as bones and teeth. Instead it refers most commonly ...
s (hardened body parts) are obsolescent or absent. The clypeus (a sclerite that makes up an insects "face") is not divided into a pre- and postclypeus, but rather separated from the front. The antennal sclerites are fused with the surrounding head capsule, but these are sometimes separated by a suture. The number of segments in the antennae vary from six in the Accorduleceridae to 30 or more in the Pamphiliidae. The compound eyes
A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...
are large with a number of facets, and there are three ocelli
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 ...
between the dorsal portions of the compound eyes. The tentorium comprises the whole inner skeleton of the head.
Three segments make up the thorax: the mesothorax
The mesothorax is the middle of the three segments of the thorax of hexapods, and bears the second pair of legs. Its principal sclerites (exoskeletal plates) are the mesonotum (dorsal), the mesosternum (ventral), and the mesopleuron (lateral) on ...
, metathorax
The metathorax is the posterior of the three segments in the thorax of an insect, and bears the third pair of legs. Its principal sclerites ( exoskeletal plates) are the metanotum (dorsal), the metasternum (ventral), and the metapleuron (lateral) ...
and prothorax
The prothorax is the foremost of the three segments in the thorax of an insect, and bears the first pair of legs. Its principal sclerites (exoskeletal plates) are the pronotum ( dorsal), the prosternum ( ventral), and the propleuron ( lateral) o ...
, as well as the exoskeletal plates that connect with these segments. The legs have spurs on their fourth segments, the tibiae. Sawflies have two pairs of translucent
In the field of optics, transparency (also called pellucidity or diaphaneity) is the physical property of allowing light to pass through the material without appreciable scattering of light. On a macroscopic scale (one in which the dimensions ...
wings. The fore and hind wings are locked together with hooks. Parallel development in sawfly wings is most frequent in the anal veins. In all sawflies, 2A & 3A tend to fuse with the first anal vein. This occurs in several families including Argidae, Diprionidae and Cimbicidae.
The larvae of sawflies are easily mistaken for lepidoptera
Lepidoptera ( ) is an order (biology), order of insects that includes butterfly, butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 Family (biology), families and 46 Taxonomic r ...
n larvae (caterpillars). However, several morphological differences can distinguish the two: while both larvae share three pairs of thoracic legs and an apical pair of abdominal proleg
A proleg is a small, fleshy, stub structure found on the ventral surface of the abdomen of most larval forms of insects of the order Lepidoptera, though they can also be found on other larval insects such as sawflies and a few other types of in ...
s, lepidopteran caterpillars have four pairs of prolegs on abdominal segments 3-6 while sawfly larvae have five pairs of prolegs located on abdominal segments 2–6; crochets are present on lepidopteran larvae, whereas on sawfly larvae they are not; the prolegs of both larvae gradually disappear by the time they burrow into the ground, therefore making it difficult to distinguish the two; and sawfly larvae only have a single pair of minute eyes, whereas lepidopteran larvae have four to six eyes on each side of the head. Sawfly larvae behave like lepidopteran larvae, walking about and eating foliage. Some groups have larvae that are eyeless and almost legless; these larvae make tunnels in plant tissues including wood. Many species of sawfly larvae are strikingly coloured, exhibiting colour combinations such as black and white while others are black and yellow. This is a warning colouration because some larvae can secrete irritating fluids from glands located on their undersides.
Distribution
Sawflies are widely distributed throughout the world. The largest family, the Tenthredinidae, with some 5,000 species, are found on all continents except Antarctica, though they are most abundant and diverse in the temperate regions of the northern hemisphere; they are absent from New Zealand and there are few of them in Australia. The next largest family, the Argidae
Argidae is a large family of sawflies, containing some 800 species worldwide, primarily in tropical regions. The larvae are phytophagous, and commonly can be found feeding (and often pupating) in groups, though very few attain pest status.
The ...
, with some 800 species, is also worldwide, but is most common in the tropics, especially in Africa, where they feed on woody and herbaceous angiosperm
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...
s. Of the other families, the Blasticotomidae and Megalodontidae are Palearctic
The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa.
The realm consists of several bioregions: the Euro-Sibe ...
; the Xyelidae, Pamphilidae, Diprionidae
The Diprionidae are a small family of conifer-feeding sawflies (thus the common name conifer sawflies, though other Symphyta also feed on conifers) restricted to the Northern Hemisphere, with some 140 species in 13 genera. Larvae are often greg ...
, Cimbicidae, and Cephidae
Cephidae is a family of stem sawflies in the order Hymenoptera. There are about 27 genera and more than 160 described species in Cephidae.
Genera
These 27 genera belong to the family Cephidae:
* '' Athetocephus'' Benson, 1935
* '' Australcep ...
are Holarctic
The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...
, while the Siricidae are mainly Holarctic with some tropical species. The parasitic Orussidae are found worldwide, mostly in tropical and subtropical regions. The wood-boring Xiphydriidae
Xiphydriidae are a family of wood wasps that includes around 150 species. They are located all over the world including North and South America, Australia, Europe, and others. Xiphydriidae larvae are wood borers in dead trees or branches of a ran ...
are worldwide, but most species live in the subtropical parts of Asia.
Behaviour and ecology
Sawflies are mostly herbivores
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
, feeding on plants that have a high concentration of chemical defences. These insects are either resistant to the chemical substances, or they avoid areas of the plant that have high concentrations of chemicals. The larvae primarily feed in groups; they are folivores
In zoology, a folivore is a herbivore that specializes in eating leaves. Mature leaves contain a high proportion of hard-to-digest cellulose, less energy than other types of foods, and often toxic compounds.Jones, S., Martin, R., & Pilbeam, D. (1 ...
, eating plants and fruits on native trees and shrubs, though some are parasitic. However, this is not always the case; Monterey pine sawfly ('' Itycorsia'') larvae are solitary web-spinners that feed on Monterey pine
''Pinus radiata'' ( syn. ''Pinus insignis''), the Monterey pine, insignis pine or radiata pine, is a species of pine native to the Central Coast of California and Mexico ( Guadalupe Island and Cedros island). It is an evergreen conifer in the f ...
trees inside a silken web. The adults feed on pollen and nectar.[
Sawflies are eaten by a wide variety of predators. While many birds find the larvae distasteful, some such as the ]currawong
Currawongs are three species of medium-sized passerine birds belonging to the genus ''Strepera'' in the family Artamidae native to Australia. These are the grey currawong (''Strepera versicolor''), pied currawong (''S. graculina''), and black ...
(''Strepera'') and stonechats (''Saxicola'') eat both adults and larvae.[ The larvae are an important food source for the chicks of several birds, including ]partridge
A partridge is a medium-sized galliform bird in any of several genera, with a wide native distribution throughout parts of Europe, Asia and Africa. Several species have been introduced to the Americas. They are sometimes grouped in the Perd ...
s. Sawfly and moth larvae form one third of the diet of nestling corn bunting
The corn bunting (''Emberiza calandra'') is a passerine bird in the bunting family Emberizidae, a group now separated by most modern authors from the finches, Fringillidae. This is a large bunting with heavily streaked buff-brown plumage. The se ...
s (''Emberiza calandra''), with sawfly larvae being eaten more frequently on cool days. Black grouse
The black grouse (''Lyrurus tetrix''), also known as northern black grouse, Eurasian black grouse, blackgame or blackcock, is a large game bird in the grouse family. It is a sedentary species, spanning across the Palearctic in moorland and step ...
(''Tetrao tetrix'') chicks show a strong preference for sawfly larvae. Sawfly larvae formed 43% of the diet of chestnut-backed chickadee
The chestnut-backed chickadee (''Poecile rufescens''), formerly ''Parus rufescens'', is a small passerine bird in the tit family, Paridae.
It is found in the Pacific Northwest of the United States and western Canada, from southern Alaska to sout ...
s (''Poecile rufescens'').[ Small carnivorous mammals such as the ]masked shrew
The cinereus shrew or masked shrew (''Sorex cinereus'') is a small shrew found in Alaska, Canada, and the northern United States. This is the most widely distributed shrew in North America, where it is also known as the common shrew.
Descriptio ...
(''Sorex cinereus''), the northern short-tailed shrew
The northern short-tailed shrew (''Blarina brevicauda'') is the largest shrew in the genus ''Blarina'', and occurs in the northeastern region of North America. It is a semifossorial, highly active, and voracious insectivore and is present in a v ...
(''Blarina brevicauda'') and the deer mouse
''Peromyscus'' is a genus of rodents. They are commonly referred to as deer mice or deermice, not to be confused with the chevrotain or "mouse deer". They are New World mice only distantly related to the common house and laboratory mouse, ''Mu ...
(''Peromyscus maniculatus'') predate heavily on sawfly cocoons. Insects such as ants and certain species of predatory wasps (''Vespula vulgaris
''Vespula vulgaris'', known as the Common wasp, is a species found in regions that include the United Kingdom, Ireland, Germany, India, China, New Zealand and Australia. It is sometimes known in English as the European wasp, but the same name is ...
'') eat adult sawflies and the larvae, as do lizards and frogs. Pardalote
Pardalotes or peep-wrens are a family, Pardalotidae, of very small, brightly coloured birds native to Australia, with short tails, strong legs, and stubby blunt beaks. This family is composed of four species in one genus, ''Pardalotus'', and seve ...
s, honeyeaters and fantail
Fantails are small insectivorous songbirds of the genus ''Rhipidura'' in the family Rhipiduridae, native to Australasia, Southeast Asia and the Indian subcontinent. Most of the species are about long, specialist aerial feeders, and named as " ...
s (''Rhipidura'') occasionally consume laid eggs, and several species of beetle larvae prey on the pupae.[
The larvae have several ]anti-predator adaptations
Anti-predator adaptations are mechanisms developed through evolution that assist prey organisms in their constant struggle against predators. Throughout the animal kingdom, adaptations have evolved for every stage of this struggle, namely by avo ...
. While adults are unable to sting, the larvae of species such as the spitfire sawfly regurgitate a distasteful irritating liquid, which makes predators such as ants avoid the larvae. In some species, the larvae cluster together, reducing their chances of being killed, and in some cases form together with their heads pointing outwards or tap their abdomens up and down. Some adults bear black and yellow markings that mimic wasps.
Parasites
Sawflies are hosts to many parasitoids, most of which are parasitic Hymenoptera; more than 40 species are known to attack them. However, information regarding these species is minimal, and fewer than 10 of these species actually cause a significant impact on sawfly populations. Many of these species attack their hosts in the grass or in other parasitoids. Well known and important parasitoids include Braconidae
The Braconidae are a family of parasitoid wasps. After the closely related Ichneumonidae, braconids make up the second-largest family in the order Hymenoptera, with about 17,000 recognized species and many thousands more undescribed. One analysis ...
, Eulophidae
The Eulophidae are a large family of hymenopteran insects, with over 4,300 described species in some 300 genera. The family includes the genus '' Elasmus'', which used to be treated as a separate family, "Elasmidae", and is now treated as a s ...
and Ichneumonidae
The Ichneumonidae, also known as the ichneumon wasps, Darwin wasps, or ichneumonids, are a family (biology), family of parasitoid wasps of the insect order Hymenoptera. They are one of the most diverse groups within the Hymenoptera with roughly 2 ...
. Braconid wasps attack sawflies in many regions throughout the world, in which they are ectoparasitoids, meaning that the larvae live and feed outside of the hosts body; braconids have more of an impact on sawfly populations in the New World than they do in the Old World, possibly because there are no ichneumonid parasitoids in North America. Some braconid wasps that attack sawflies include '' Bracon cephi'', '' B. lisogaster'', '' B. terabeila'' and '' Heteropilus cephi''. Female braconids locate sawfly larvae through the vibrations they produce when feeding, followed by inserting the ovipostior and paralysing the larva before laying eggs inside the host. These eggs hatch inside the larva within a few days, where they feed on the host. The entire host's body may be consumed by the braconid larvae, except for the head capsule and epidermis. The larvae complete their development within two or three weeks.
Ten species of wasps in the family Ichneumonidae attack sawfly populations, although these species are usually rare. The most important parasitoids in this family are species in the genus ''Collyria''. Unlike braconids, the larvae are endoparasitoids, meaning that the larvae live and feed inside the hosts body. One well known ichneumonid is '' Collyria coxator'', which is a dominant parasitoid of ''C. pygmaeus''. Recorded parasitism rates in Europe are between 20 – 76%, and as many as eight eggs can be found in a single larva, but only one ''Collyria'' individual will emerge from its host. The larva may remain inside of their host until spring, where it emerges and pupates.
Several species in the family Eulophidae attack sawflies, although their impact is low. Two species in the genus ''Pediobius
''Pediobius'' is a genus of hymenopteran insects of the chalcid wasp family Eulophidae. Like their relatives, the larvae of these diminutive wasps are parasitoids of various arthropods (mainly insects). Some ''Pediobius'' are used in biologic ...
'' have been studied; the two species are internal larval parasitoids and have only been found in the northern hemisphere. Parasitism of sawflies by eulophids in grass exceeds 50%, but only 5% in wheat. It is unknown as to why the attack rate in wheat is low. Furthermore, some fungal and bacterial diseases are known to infect eggs and pupa in warm wet weather.[
Outbreaks of certain sawfly species, such as '' Diprion polytomum'', have led scientists to investigate and possibly collect their natural enemies to control them. Parasites of ''D. polytomum'' have been extensively investigated, showing that 31 species of hymenopterous and dipterous parasites attack it. These parasites have been used in successful biological control against pest sawflies, including ''Cephus cinctus'' throughout the 1930s and 1950s and ''C. pygmaeus'' in the 1930s and 1940s.
]
Life cycle and reproduction
Like all other hymenopteran insects, sawflies go through a complete metamorphosis
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 Endopterygo ...
with four distinct life stages – egg, larva, pupa and adult. Many species are parthenogenetic
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and developmen ...
, meaning that females do not need fertilization to create viable eggs. Unfertilized eggs develop as male, while fertilized eggs develop into females (arrhenotoky
Arrhenotoky (from Greek -τόκος ''-tókos'' "birth of -" + ἄρρην ''árrhēn'' "male person"), also known as arrhenotokous parthenogenesis, is a form of parthenogenesis in which unfertilized eggs develop into males. In most cases, parthe ...
). The lifespan of an individual sawfly is two months to two years, though the adult life stage is often very short (approximately 7 – 9 days), only long enough for the females to lay their eggs.[ The female uses its ovipositor to drill into plant material to lay her eggs (though the family ]Orussoidea
Orussoidea is a superfamily of sawflies. It contains the living family Orussidae, as well as the extinct families Burmorussidae and Paroryssidae. They are the group of sawflies closest to the Apocrita, the group containing wasps, bees and ants, w ...
lay their eggs in other insects). Plant-eating sawflies most commonly are associated with leafy material but some specialize on wood, and the ovipositors of these species (such as the family Siricidae) are specially adapted for the task of drilling through bark. Once the incision has been made, the female will lay as many as 30 to 90 eggs. Females avoid the shade when laying their eggs because the larvae develop much slower and may not even survive, and they may not also survive if they are laid on immature and glaucous leaves. Hence, female sawflies search for young adult leaves to lay their eggs on.[
These eggs hatch in two to eight weeks, but such duration varies by species and also by temperature. Until the eggs have hatched, some species such as the small brown sawfly will remain with them and protects the eggs by buzzing loudly and beating her wings to deter predators. There are six larval stages that sawflies go through, lasting 2 – 4 months, but this also depends on the species. When fully grown, the larvae emerge from the trees en masse and burrow themselves into the soil to pupate. During their time outside, the larvae may link up to form a large colony if many other individuals are present. They gather in large groups during the day which gives them protection from potential enemies, and during the night they disperse to feed. The emergence of adults takes awhile, with some emerging anywhere between a couple months to 2 years. Some will reach the ground to form pupal chambers, but others may spin a cocoon attached to a leaf. Larvae that feed on wood will pupate in the tunnels they have constructed. In one species, the jumping-disc sawfly (''Phyllotoma aceris'') forms a cocoon which can act like a parachute. The larvae live in sycamore trees and do not damage the upper or lower cuticles of leaves that they feed on. When fully developed, they cut small ]perforation
A perforation is a small hole in a thin material or web. There is usually more than one perforation in an organized fashion, where all of the holes collectively are called a ''perforation''. The process of creating perforations is called perfor ...
s in the upper cuticle to form a circle. After this, they weave a silk hammock
A hammock (from Spanish , borrowed from Taíno and Arawak ) is a sling made of fabric, rope, or netting, suspended between two or more points, used for swinging, sleeping, or resting. It normally consists of one or more cloth panels, or a wo ...
s within the circle; this silk hammock never touches the lower cuticle. Once inside, the upper-cuticle's disc separates and descends towards the surface with the larvae attaching themselves to the hammock. Once they reach the round, the larvae work their way into a sheltered area by jerking their discs along.[
The majority of sawfly species produce a single generation per year, but others may only have one generation every two years. Most sawflies are also female, making males rare.][
Cladius difformis Cladius may refer to:
* ''Cladius'' (sawfly), a genus of sawflies in the family Tenthredinidae
* Cladius Detlev Fritzsch (1765–1841), Danish painter
* Cladius Labib (1868–1918), Egyptian Egyptologist
See also
* Claudius (disambiguation)
Cla ...]
'', the bristly rose slug">
File:Cladius difformis larva.jpg, Larva
File:Cladius difformis pupa dorsal.jpg, Pupa, dorsal view
File:Cladius difformis pupa ventral.jpg, Pupa, ventral view
File:Cladius difformis female.jpg, Female
File:Cladius difformis male.jpg, Male
. Species in the Diprionidae, such as the pine sawflies, ''
s in regions such as Scandinavia. ''D. pini'' larvae defoliated in the largest outbreak in Finland, between 1998 and 2001. Up to 75% of the trees may die after such outbreaks, as ''D. pini'' can remove all the leaves late in the growing season, leaving the trees too weak to survive the winter. Little damage to trees only occurs when the tree is large or when there is minimal presence of larvae. ''Eucalyptus'' trees can regenerate quickly from damage inflicted by the larvae; however, they can be substantially damaged from outbreaks, especially if they are young. The trees can be defoliated completely and may cause "dieback", stunting or even death.