Family: Dytiscidae (water beetles)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthopoda > Mandibulata > Atelocerata > Panhexapoda > Hexapoda > Insecta (insects) > Dicondyla > Pterygota > Metapterygota > Neoptera > Eumetabola > Holometabola > Coleoptera (beetles) > Suborder: Adephaga

Aquatic predatory beetles, ranging widely in size (1 - 45 mm long). The colour varies from pale yellow/brown to brown. The mouthparts are strongly formed for dismembering prey while the mouthparts of the larvae pierce and suck. The hind legs are flattened and paddle-like and adapted for swimming. There are about 40 genera and 250 species of dytiscids in southern Africa. 

Cybister tripunctatus, Yellow-edge Water Beetle, 29mm. [image by M. Picker & C. Griffiths ©, from Field Guide to Insects of South Africa, used with permission].	Hydaticus bivittatus, 15mm. [image by M. Picker & C. Griffiths ©, from Field Guide to Insects of South Africa, used with permission].

Adults and larvae feed mainly on aquatic insects and crustaceans. They are able to remain under water for fairly long periods by keeping a supply of air in the subelytral cavity (i.e. beneath the elytra) and occasional replenishment of the air supply is needed for both respiration and buoyancy. They feed on aquatic insects and crustaceans and occur in both fresh, stagnant or running water.

Eggs are laid under various submerged objects such as vegetation or stones but in some species, eggs are laid within plant tissue. Larvae pass through three instars before pupating on land near the water. 

Publications

• Biström, O. 1979. A revision of the genus Derovatellus Sharp (Coleoptera, Dytiscidae) in Africa. Acta Entomologica Fennica 35: 1-28.

• Biström, O. 1982. A revision of the genus Hyphydrus Illiger (Coleoptera, Dytiscidae). Acta Zoologica Fennica 165: 1-121.

• Biström, O. 1983. Revision of the genera Yola Des Gozis and Yolina Guignot (Coleoptera, Dytiscidae). Acta Zoologica Fennica 176: 1-67. 

• Omer-Cooper, J. 1965. Coleoptera. Dytiscidae. In Hanström, B., Brinck, P. & Rudebeck, G. (eds) South African Animal Life 11: 59-214. Almqvist Wiksell, Stockholm.

• Omer-Cooper, J. 1974. The species of Bidessus Sharp (Coleoptera: Dytiscidae) of Africa south of the Sahara including Madagascar. Journal of the Entomological Society of Southern Africa 37(2): 305-341. 

• Omer-Cooper, J. 1979. The species of Bidessus Sharp (Coleoptera: Dytiscidae) of Africa south of the Sahara including Madagascar. Journal of the Entomological Society of Southern Africa 42(2): 197-216. 

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