Upper Carboniferous to Recent. One of the dominant groups of the late Palaeozoic.
- eggs usually contained in ootheca
- leathery forewings.
- male genitalia asymmetrical
- cerci variable, with one or more segments
There are over 4,000 species of roaches spread all around the globe, and lots more still unknown to science. In Michigan there are only a couple of dozen species, and about half of them are invaders that came along with European settlers.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native )
Cockroaches are long, flat, brown insects. Their heads point downward and have chewing mouthparts. A plate from the top of the thorax covers the head when you look down on them, so you can't actually see the head. They are very fast runners. They have long antennae, and at the end of the abdomen are two short antennae-like structures that sense air current and vibrations.
Other Physical Features: ectothermic ; bilateral symmetry
Sexual Dimorphism: female larger
Most cockroach species live in dead leaves and soil on the ground in forests. A few well-known species have adjusted to living with people in houses and other buildings.
Habitat Regions: temperate ; tropical ; terrestrial
Terrestrial Biomes: taiga ; desert or dune ; chaparral ; forest ; rainforest ; scrub forest ; mountains
Roaches are scavenging omnivores, they'll eat just about any organic matter they can find. They don't have a powerful bite, so they don't usually eat living animals.
In wild habitats, roaches help breakdown dead plants and animal waste.
Ecosystem Impact: biodegradation
Most roach species don't have any special defenses, they just hide, only come out in the dark, and run fast. A few species have chemical defenses.
- small Squamata
Known prey organisms
Based on studies in:
Costa Rica (Carrion substrate)
This list may not be complete but is based on published studies.
- L. F. Jiron and V. M. Cartin, 1981. Insect succession in the decomposition of a mammal in Costa Rica. J. New York Entomol. Soc. 89:158-165, from p. 163.
- Myers, P., R. Espinosa, C. S. Parr, T. Jones, G. S. Hammond, and T. A. Dewey. 2006. The Animal Diversity Web (online). Accessed February 16, 2011 at http://animaldiversity.org. http://www.animaldiversity.org
Life History and Behavior
Communication and Perception
Most roach species use touch and taste/smell as primary senses, but some also communicate with vibrations or other sounds. They hiss, or rub their wings together. The sound startles predators and gives roach a chance to escape, and is sometimes used to attract the opposite sex.
Cockroaches have incomplete metamorphosis. Immature roaches look pretty much like adult roaches, except they don't have wings yet. As they grow the molt (shed their whole skin at once) several times. After the last molt, they roach has wings and can reproduce. It stops growing and molting at that point.
Lifespans vary with species. Some can live for two years.
Female roaches produce dozens of offspring several times in their lives. Most species produce an egg case with up 40 eggs. A few species keep the eggs in their abdomen until they hatch, and some actually give birth to live young.
Breeding season: Wild roaches breed in the summer, but in urban habitats they can breed any time.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; sexual ; fertilization (Internal ); viviparous ; ovoviviparous ; oviparous
Most roach species, including the ones that live in houses, don't have any parental care. In some of the woodland species females guard over their young for a short time after they hatch. A few species live together in burrows in dead wood.
Parental Investment: no parental involvement; female parental care
No roach species are considered endangered.
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
Cockroaches are the biggest household pest problem in most cities and towns. They spread bacteria that can make people sick.
Negative Impacts: injures humans (carries human disease); household pest
Economic Importance for Humans: Positive
The great majority of roach species never bother people. They live outside, and are a harmless part of foodwebs.
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