Difference Between Roaches and Water Bugs

Roaches vs Water Bugs

When the cockroaches are considered, the common names such as roaches and water bugs are always misleading, as they are used to refer the same group of animals in some regions. Despite the term water bug means the hemipteran insects, it is being used to refer the cockroaches in some places of the world. Therefore, for a clear idea about these animals, the characteristics of the water bugs and cockroaches should be well understood, and those are quite easy to follow, as well. This article intends to provide adequate information about both roaches and water bugs, so that even an average person should be able to understand the difference between them.


Roaches 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 roaches, but only four species have become serious pests. However, about 30 species of roaches have been living around the human habitations. The most important aspect of the roaches is that their ability to withstand the mass extinctions. In a simple term, roaches 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, roaches are large with about 15 – 30 millimetres long body. The largest recorded species is the Australian giant burrowing roach 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 roaches. 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. Roaches could be serious pests not only for food destroyers, but also as dispersal agents of diseases such as asthma.

Water Bugs

There are few types of insects referred as water bugs, but only the true water bugs are considered in this article. True water bugs belong to the Infraorder: Neomorpha of the Order: Hemiptera. They are referred as true water bugs, as their habitat being water. The earliest fossil of a water bug dates back to 250 million years. Currently, there are about 2,000 water bug species, and they are distributed all over the world except in the Polar Regions. The majority of true water bugs live in freshwaters while there are some brackish water and saltwater species, as well. They to be hemipterans, their forewing is hardened anteriorly but not the posterior half. The ocelli are absent in water bugs, but sometimes those are vestigial. Water bugs are usually omnivorous insects, and they feed on both plant matter and prey upon small invertebrates and small larvae of amphibians. However, there are some giant water bug species with the capability of preying upon some fish and amphibian species.


What is the difference between Roaches and Water Bugs?

• Roaches are more diversified than water bugs.

• Roaches exist more than 100million years before the water bugs did.

• Roaches are more generalised than water bugs are.

• The fore wings are hardened fully in roaches, whereas only the anterior half of the forewings is hardened in water bugs.

• Roaches could be serious pests but not the water bugs.

• Body is dorso-ventrally flattened in roaches but not in water bugs.

• Roaches have a large pair of eyes, but the ocelli are vestigial or absent in water bugs.