Dytiscus

Dytiscus ('little diver' based on Greek δυτικός, 'able to dive' and the diminutive suffix -ίσκος) is a Holarctic genus of predaceous diving beetles that usually live in wetlands and ponds. There are 26 species in this genus distributed in Europe, Asia, North Africa and North and Central America. They are predators that can reduce mosquito larvae. Dytiscus are large water beetles with a robust, rounded shape and they measure 2.2–4.4 cm (0.9–1.7 in) long depending on the exact species involved. The largest, D. latissimus, is among the largest species in the family and its size is only matched by certain Megadytes. The tarsi of the males are modified into suckers which are used to grip the female in mating. Females are usually larger than the males and come in two forms, with grooved (sulcate) or smooth elytra. Males only ever have smooth elytra. The adults of most species can fly.