Cockroach vs Beetle
Both cockroach and beetle are insects, and they are amongst the most diversified eukaryotic group among animals. There are several important differences between them and those are much important to be aware of for a sensible identification of the cockroach from a beetle. This article intends to present their characteristics, especially the most interesting distinguishing characters, and finally follows up with a comparison between the two.
Cockroaches are a highly diversified group of insects with more than 4,500 species, and they are classified under the Order: Blattodea. There are eight families of cockroaches, but only four species have become serious pests. However, about 30 species of cockroaches have been living around the human habitations. The most important aspect of the cockroaches is that their ability to withstand the mass extinctions. In a simple term, cockroaches have never failed to survive any of the mass extinctions taken place on the Earth since their beginning 354 million years ago, in the Carboniferous period. Compared to most of the other insects, cockroaches are large with about 15 – 30 millimetres long body. The largest recorded species is the Australian giant burrowing cockroach with about a nine-centimetre long body. They all have a dorso-ventrally flattened body with a small head. The mouthparts are adapted to feed on any type of food, which is an indication of their generalised food habits. Therefore, whatever is available could be food for cockroaches. Their basis of survival through more than 350 million years is well explained using their generalised food habits. They have large compound eyes and two long antennae. The whole body is not as hard as in many insects, but the first pair of wings are hard and the second pair is membranous. Their legs have coxae and claws for protection and other functions. Cockroaches could be serious pests not only for food destroyers, but also as dispersal agents of diseases such as asthma.
Beetles are the most diversified group of insects consisting over 400,000 species, which accounts for more than 40% of the total number of insects and 25% of all known life forms. Beetles belong to the Order: Coleoptera, they have been able to conquer almost all the ecosystems, and are widely distributed except in Polar Regions and sea. Beetles usually inhabit the wild ecosystems and not found around human habitations. The body of a beetle is tough with hardened fore wings (elytra), thorax, and head. The hind wings are soft and membranous. The hardened stature is due to the presence of numerous defensive plates called sclerites. Their mouthparts are designed as pincers, to feed on preys, as they are predatory insects. Beetles undergo complete metamorphosis through the four stages egg, larva, pupa, and adult. Therefore, they are called as endopterygotes. Since beetles are predators of other insects, they are sometimes friends of humans.
What is the difference between Cockroach and Beetle?
• Beetles are usually smaller than cockroaches in their body sizes.
• Beetles are substantially more diversified than cockroaches, when the numbers of species of the respective groups are compared.
• Cockroaches undergo incomplete metamorphosis with only three stages, whereas beetles undergo the complete metamorphosis with four stages in their lifecycle.
• Body of the cockroaches is dorso-ventrally flattened but not in beetles.
• Beetles have a much harder body than cockroaches do.
• Cockroaches are generalists, but beetles are specialised feeders for carnivorous diets.
• Cockroaches are pests while beetles are friends of humans.