What Are Cockroaches?
Whether they’re digesting wood pulp in a rainforest or hiding under a refrigerator, cockroaches are fascinating. They’re primitive insects — they existed millions of years before dinosaurs did and have evolved very little since then. In spite of their unchanging nature, they’ve survived when other species have not. For example, dinosaurs became extinct 65 million years ago, but cockroaches have thrived for 320 million years.
Cockroaches are generally rather large insects. Most species are about the size of a thumbnail, but several species are bigger. The world’s heaviest cockroach is the Australian giant burrowing cockroach, which can reach 9 centimetres (3.5 in) in length and weigh more than 30 grams (1.1 oz). Comparable in size is the Central American giant cockroach blaberus giganteus, which grows to a similar length but is not as heavy.
Cockroaches have been around for millions of years, evolving into some of the most adaptable pests on Earth. There are approximately 4,000 living species of cockroaches in the world. About 70 of these species are found in the United States. Cockroaches are commonly found in buildings and homes because they prefer warm environments close to food and water. Unfortunately, cockroaches can cause allergies and trigger asthma attacks, especially in children. They can also spread nearly 33 different kinds of bacteria.
Cockroaches have a broad, flattened body and a relatively small head. They are generalized insects, with few special adaptations, and may be among the most primitive living neopteran insects. The mouthparts are on the underside of the head and include generalised chewing mandibles. They have large compound eyes, two ocelli, and long, flexible, antennae.
Some female cockroaches only mate once and stay pregnant for life! Insects, unlike mammals, do not have a uterus and therefore do not typically have young which gestate. Some individuals may call the development of cockroaches in the eggs “gestation.” As such, cockroach “gestation” begins when a female specimen creates an ootheca, or an egg case, which contains a number of eggs. Most species deposit this egg case in a safe, protective area, where it remains until it hatches.
However, females of some species, such as German cockroaches, carry the ootheca attached to their abdomens until it hatches. Other species, like the Madagascar hissing cockroach, retain the ootheca inside their body until the nymphs are ready to hatch and give the illusion of live birth.
After hatching, nymphs are ghostly white and soft. Once their exoskeleton hardens they will darken and become their normal color. Cockroach’s nymphs undergo a series of molts until they eventually become adults. Adults of many species can be distinguished from nymphs by their larger size and the presence of wings. However, a few species of cockroach, like the Madagascar hissing cockroach, lack wings even as adults.
Cockroaches can survive for up to a month with their heads cut off. Yes it is true. Cockroaches do not have blood pressure as mammals do. Therefore, cutting off their head would not cause them to die from bleeding. Nor do cockroaches need their heads to breathe. They only require their heads to eat. After about a month without their head (though probably much sooner), they would die of starvation.