Waterbugs are aquatic insects that spend most of the time in water, whereas cockroaches are adaptable insects that enjoy moist places but are not aquatic. Waterbugs eat insects, small fish and tadpoles. Cockroaches are scavengers that feed on anything including decaying or fermented food.
Waterbugs live in water or sometimes mud. They use their legs to paddle through the water, their bodies to float in water, and their wings to fly between water sources. Waterbugs are more diverse in color than cockroaches and have smaller antennae.
Cockroaches live on land and infest homes and other undesired places. They are nocturnal and prefer dark, hidden crevices. Since some cockroaches gravitate to sewers and other damp places, they sometimes get confused with waterbugs. Cockroaches eat anything but do not kill or hunt for food like the waterbug. Cockroaches can spread human disease and trigger allergies, though they do not bite humans. Waterbugs, on the other hand, occasionally bite humans.
Since waterbugs live in habitats with water, they normally are not a concern to humans. Cockroaches, however, are common pests controlled through proper sanitation, baits or traps, or with the help of an exterminator.