There are nearly four thousand species of Cockroaches in the world, of which only twenty five to thirty or less than one percent have any pest status, the rest are innocent members of the Earths fauna, some of which are clean living, non aggressive and slow moving, and as such make great pets. The largest known Cockroaches in the world are cockroaches with the largest wingspan up to eighteen centimeters is the Megaloblatta longipennis, largest body, Macropanesthia rhinocerus from Australia weighing in at up to fifty grams. The smallest known is Attaphilla fungicola which lives in the nests of Leaf Cutter ants of the genus Atta in North America and feeds on the fungus they farm, it is about four mm long.
Cockroaches have been on the Earth for at least two hundred million years and it is possible that in the late carboniferous cockroaches out numbered, in terms of number of individuals all other flying insects. Most Cockroaches are tropical in habitat and Britain has only three native species, which is less than the number of introduced species. Many Cockroaches are diurnal, though most are nocturnal. Many are forest floor species though some are cave dwellers, some are semi aquatic, some burrowing, some wood boring, and some even make their homes in the nests of social insects.
Cockroaches are related to Termites or Isoptera, which some authorities believe arose seventy to fifty million years ago as an offshoot or possibly two offshoots of the Cockroach lineage of the time. Two pieces of evidence supporting this is the fact that Termites are Eusocial insects and some species of Cockroach are primitively subsocial, and the gut microflora of the primitive wood eating Cockroaches, such as Cryptocercus punctulatus, are very similar to that of the Termites. Modern Cockroaches are more similar to their ancient fossil ancestors than any other extant or still living insect.
A hemimetabolous insect with an oval somewhat flattened head partially concealed by the pronotum and with the mouth pointing backwards between the fore coxa.
The antennae are filiform or long and thin, and inserted below the middle of the eyes, the mouthparts are adapted for biting, chewing and licking while the compound eyes are usually large and irregularly hemispherical being wider near the vertex or the top of the front of the head. The forewings are usually hardened and often opaque, the hind wings are membranous. The legs are almost equal in length and depressed beneath the body. The abdomen has ten segments but only seven or eight visible from above while from beneath nine plates are visible in the male but only seven in the female. Males and nymphs carry two smaller appendages thinner than and below the cerci called styles.
The eggs are laid in an ootheca or natures answer to the polystyrene egg box. Some species will secrete these in the corners of the cage or other accessible nooks and crannies while others will carry the ootheca around with them, either inside or partly extruded from the body until it is time for the young to hatch.
The Oothecae contain fourteen to twenty eight eggs. Incubation time for the eggs is temperature dependant and hatching takes approximately thirty five days at thirty degrees Centigrade and fifty nine days at twenty degrees Centigrade. Incubation time is more temperature dependant for Periplaneta americana than for any other species of Cockroach so far studied. Nymphs take up to fifteen months or longer to reach maturity depending on the temperature and the availability of food, females normally undergo nine moults while males normally take thirteen. Life expectancy ranges from two to four years and a female can produce thirty oothecae resulting in one thousand young before dying of old age.
Virgin females are known to produce sex attractants in P.americana and some other species, these can attract a male in as small amounts as times ten to the minus fourteen micrograms. Courtship involves antennal sparring and the male raising and fluttering his wings. The female then feeds on the secretions of the males dorsal glands, situated on the upper surface of his abdomen. Following this the male moves backwards under the female until he is able to clasp her genitalia from beneath, once contact is assured the two assume the more familiar end to end position, mating normally lasts about one hour.
Pycnoscelus surinamensis is not only parthenogenetic, and thus has no courtship or sex, but is also ovoviviparous meaning that the ootheca is first extruded and then brought back into the females brood pouch for incubation.
Apart from Mankind Cockroaches are eaten by a wide range of small mammals, birds, reptiles and amphibians. The Cockroach mite Pimeliaphilus cuniliffei feeds on all Cockroach life stages and can cause considerable damage to infested populations.
Mankinds long relationship with Cockroaches probably began with the Cockroaches as food items, but the relationship really took off when Humans started storing food for the winter and continued to improve the better we became at creating artificially stable habitats with plenty of food.
