Cockroaches are cursorial insects with five-segmented tarsi and none of the
legs modified for digging or grasping. They are very fast runners, as anyone
who attempts to step on one soon discovers.
- The body is oval and flattened.
- The head is concealed from above by the pronotum.
- Tympana and stridulating organs (usually) are absent.
- Wings are generally present, though in some species they are much reduced.
- The females of many species have shorter wings than the males.
- The cerci are one- to many-segmented and usually fairly long.
- The antennae are long and filiform.
Key to the Families of the Blattaria:
- 1. Length 3 mm or less; found in ant nests (Attaphila, Myrmecoblatta)..........Polyphagidae*
- 1'. Length over 3 mm; almost never found in ant nests..........2
- 2(1'). Middle and hind femora with numerous spines on ventroposterior margin..........3
- 2'. Middle and hind femora without spines on ventroposterior margin, or
with hairs and bristles only, or 1 or 2 apical spines..........7
- 3(2). Pronotum and front wings densely covered with silky pubescence; length 27 mm or
more (tropical species accidental in the United States)(Nyctibora)..........Blattellidae*
- 3'. Pronotum and front wings glabrous or only very sparsely pubescent..........4
- 4(3'). Ventroposterior margin of front femora with row of spines that either decrease
gradually in size and length distally or are nearly equal in length throughout..........5
- 4'. Ventroposterior margin of front femora with row of heavy spines proximally and
more slender and shorter spines distally..........6
- 5(4). Female subgenital plate divided longitudinally; male
styli similar, slender, elongate, and straight; length 18 mm or
more (Blatta, Periplaneta, Eurycotis, Neostylopyga)..........Blattidae
- 5'. Female subgenital plate entire, not divided longitudinally; male styli variable,
often modified, asymmetrical, or unequal in size; length variable, but usually less
than 18 mm (Supella, Cariblatta, Symploce, Pseudomops,
- 6(4'). Front femora with only 1 apical spine; supra-anal plate weakly bilobed;
color glossy light brown, with sides and front of pronotum and basal costal part of
front wings yellowish; 15-20 mm in length; Florida Keys (Phoetalia,
- 6" Front femora with 2 or 3 apical spines; supra-anal plate not bilobed; size and
color variable; widely distributed (Ectobius, Latiblatella,
Ischnoptera, Parcoblatta, Euthlastoblatta, Aglaopteryx)..........Blattellidae
- 7(2'). Distal portion of abdomen (usually including cerci) covered by produced
seventh dorsal and sixth ventral abdominaal sclerites, subgenital plate absent;
wingless, body almost parallel-sided, shining reddish brown, finely punctate,
23-29 mm in length; widely distributed, usually found in rotting logs..........Cryptocercidae*
- 7'. Distal portion of abdomen not so covered, subgenital plate present; wings
usually well developed (absent in some females); usually oval in shape; size and
color variable; mostly southern United States..........8*
- 8(7'). Hind wings with an apical portion (intercalated triangle or appendicular area)
that folds over when wings are in resting position; 8.5 mm in length or less, and
glossy yellowish in color, often beetlelike in appearance; southeastern United States
- 8'. Hing wings not as above..........9*
- 9(8'). Front femora with 1 to 3 spines on ventrposterior margin and 1 at tip;
length over 40 mm; arolia present; southern Florida (Blaberus,
- 9'. Front femora without spines on ventroposterior margin and with 1 or a few
at tip; size variable; arolia present or absent; eastern and southern United
- 10(9'). Wings well developed, the anal area of hind wings folded fanwise at rest;
fons flat, not bulging; length over 16 mm, or pale green in color (Panchlora,
Pycnoscelus, Nauphoeta, Leucophaea)..........Blaberidae*
- 10'. Anal area of hind wings flat, not folded fanwise at rest (some females are
wingless); frons thickened and somewhat bulging; usually (except some Arenivaga)
less than 16 mm in length and never green (Holocompsa, Eremoblatta,
Cockroaches are primarily tropical insects, and most of our species occur in
the southern part of the United States. Some tropical species are occasionally
brought into the North in shipments of bananas or other tropical fruits. The
most commonly encountered cockroaches in the North are those that invade
houses, where they are often serious pests. None is known to be specific
vector of disease, but they feed on all sorts of things in a house. They
contaminate food, they have an unpleasant odor, and their presence is often
These insects are rather general feeders. The eggs are enclosed in capsules or
oothecae, which may be deposited immediately after they are formed,
carried about on the abdomen of the female until they hatch, or carried
internally in a uterus or brood pouch for the full gestation period.
How to encounter|
Cockroaches are mainly nocturnal creatures, and night is often the best time
to collect them. They may be found by searching in leaf litter or under bark,
or by overturning fallen logs. Many species, including the common household
pests, can be caught by putting molasses or a similar bait in the bottom of a
pitfall trap placed in the ground. Insects so collected can simply be picked
out of the trap.
Most nymphs and some soft-bodied adult specimens should be preserved in alcohol,
but most adults can be pinned. The pin should be placed through the right tegmen,
in about the middle (from front to rear) of the body. If the specimen is very
soft-bodied, the body should be supported by a piece of cardboard or by pins;
otherwise, it will sag at either end.
Casandra Lloyd and Sara Serji, University of Georgia, Athens.
Thanks to Sabina Gupta, Denise Lim, and Dr. John Pickering for technical and web support in developing this page.
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Kids' Inquiry of Diverse Species
This scientific name is not yet recognized in our classification database.
What do they look like?
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.
Where do they live?
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.
What kind of habitat do they need?
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.
How do they grow?
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.
How long do they live?
Lifespans vary with species. Some can live for two years.
How do they behave?
Most roaches are solitary nocturnal scavengers. Those living in buildings prefer locations that are warm and or damp. A few wild species are more social and live in groups. These species can eat wood (they have special microbes in their guts like termites) and live in decaying logs.
How do they communicate with each other?
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.
What do they eat?
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.
What eats them and how do they avoid being eaten?
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.
What roles do they have in the ecosystem?
In wild habitats, roaches help breakdown dead plants and animal waste.
Do they cause problems?
Cockroaches are the biggest household pest problem in most cities and towns. They spread bacteria that can make people sick.
Ways that these animals might be a problem for humans
How do they interact with us?
The great majority of roach species never bother people. They live outside, and are a harmless part of foodwebs.
Are they endangered?
No roach species are considered endangered.
IUCN Red List
George Hammond (author), Animal Diversity Web.
Animal Diversity Web
Hammond, G. . "" (On-line), Animal Diversity Web. Accessed August 21, 2019 at http://www.biokids.umich.edu/accounts//
BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the
University of Michigan
School of Education
University of Michigan
Museum of Zoology
, and the
Detroit Public Schools
. This material is based upon work supported by the
National Science Foundation
under Grant DRL-0628151.
Copyright © 2002-2019, The Regents of the University of Michigan. All rights reserved.
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