''Therea petiveriana'', variously called the desert cockroach, seven-spotted cockroach, or Indian domino cockroach, is a species of crepuscular cockroach found in

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 ...

and Sri Lanka. They are members of a basal group within the cockroaches. This somewhat roundish and contrastingly marked cockroach is mainly found on the ground in

scrub forest Shrubland, scrubland, scrub, brush, or bush is a plant community characterized by vegetation dominated by shrubs, often also including grasses, herbs, and geophytes. Shrubland may either occur naturally or be the result of human activity. It ma ...

habitats where they may burrow under leaf litter or loose soil during the heat of the day.

Description

The black and white pattern of adults is believed to have evolved to

mimic MIMIC, known in capitalized form only, is a former simulation computer language developed 1964 by H. E. Petersen, F. J. Sansom and L. M. Warshawsky of Systems Engineering Group within the Air Force Materiel Command at the Wright-Patterson AFB in ...

the pattern of the aggressive

ground beetle Ground beetles are a large, cosmopolitan family of beetles, the Carabidae, with more than 40,000 species worldwide, around 2,000 of which are found in North America and 2,700 in Europe. As of 2015, it is one of the 10 most species-rich animal f ...

Anthia sexguttata ''Anthia sexguttata'', the six-spot ground beetle, is a beetle of the Family Carabidae. Appearance Adults measure approximately 4 cm (1.5 inches), are black with six relatively large, white, dorsal spots (four over the elytra and two on th ...

'' that has strong defenses, including the ability to spray chemical irritants. The upperside of the abdomen is orange-yellow, but is hidden by the

tegmina A tegmen (plural: ''tegmina'') designates the modified leathery front wing on an insect particularly in the orders Dermaptera ( earwigs), Orthoptera (grasshoppers, crickets and similar families), Mantodea (praying mantis), Phasmatodea (stick an ...

. The spots on the asymmetrical tegmina are placed so that when closed, the spots appear symmetrical. The right tegmen lobe is bright orange-yellow. The species has been said to be one of the few cockroaches with "grace and beauty". The head is bent back underneath the pronotal shield (hypognathous) and the

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 ...

(simple eyes) face forward, helping sense light and thereby time, and they forage actively during early morning and late evening.

Reproduction

Once a female has copulated with a male, she does not allow other males to approach, kicking them away with her hind legs. The eggs are laid in

leaf litter Plant litter (also leaf litter, tree litter, soil litter, litterfall or duff) is dead plant material (such as leaves, bark, needles, twigs, and cladodes) that have fallen to the ground. This detritus or dead organic material and its constituent ...

. Up to 13

ootheca An ootheca (pl. ''oothecae'' ) is a type of egg mass made by any member of a variety of species including mollusks (such as ''Turbinella laevigata''), mantises, and cockroaches. The word is a Latinized combination of ''oo-'', meaning "egg", f ...

e are produced by a female over 3 to 40 days (blocking the ocelli of the females has been found to inhibit the laying of eggs). The oothecae are produced as in other cockroaches by the secretions from the asymmetrical colleterial glands of the females. Once the ootheca is extruded it is deposited in suitably moist leaf litter. Nymphs lead a life hidden below the ground and may go as deep as 30 cm during the

dry season The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The te ...

Taxonomy

This is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

for the genus ''Therea''. The species epithet is after

James Petiver James Petiver (c. 1665 – c. 2 April 1718) was a London apothecary, a fellow of the Royal Society as well as London's informal Temple Coffee House Botany Club, famous for his specimen collections in which he traded and study of botany and entom ...

(1663–1718), who obtained specimens from southern India and Sri Lanka (probably from the surgeon at Fort St. George, either Samuel Browne or more likely

Edward Bulkley Edward Bulkley (died 10 August 1714) was an East India Company surgeon (1602-1709) posted in Madras and a pioneer naturalist. He corresponded with James Petiver and was the first to document the bird species of which a list of birds was published ...

Carl Linnaeus Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his Nobility#Ennoblement, ennoblement in 1761 as Carl von Linné#Blunt, Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalise ...

placed the species under ''Cassida'' and described ''C. petiveriana'' and another that he called ''C. septemguttata'', now considered a synonym.

Communication

Like other cockroaches, ''T. petiveriana'' uses chemical

pheromones 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 ...

to communicate with each other. When disturbed, they are said to raise their wings and evert lateral glands on the second and third abdominal segments. Their glandular secretions were found to contain volatile compounds N-3-methylbutylacetamide (MBA) and N-3-methylbutylpropanamide (MBP), making up nearly 60% of the volatile fraction. These chemicals appeared to induce alarm behaviour.

Digestion

Like termites, these cockroaches have symbiotic flagellates and bacteria in their gut that aid in digestion.

As pets

This species is popular as a pet in many parts of the world and is easy to keep.

References

{{Taxonbar, from=Q4668272 Insects of India Insects described in 1758 Taxa named by Carl Linnaeus Cockroaches