Habitat
Adults: aquatic
Immatures: aquatic

Feeding Habits
Adults: predaceous
Immatures: predaceous

North American
Species: 475

Coleoptera Dytiscidae
Predaceous diving beetles

Special Characteristics: Dytiscidae are usually black or dark brown, sometimes with green, bronze or brown stripes or spots. The body is oval in shape and very hard, and the hind legs are flattened and fringed for swimming.

Comments: They are very common in ponds and quiet streams. Predaceous diving beetles swim by moving their hind legs simultaneously like a frog; which differentiates them from the similar looking water scavenger beetles (family Hydrophilidae), who move their hind legs alternately. The adults sometimes leave the water at night to fly to other water bodies. While flying they are often attracted to lights. The larvae are sometimes called water tigers. Both the larvae and adults are predaceous and feed on other aquatic arthropods and small aquatic animals including fish.

Species:
Dytiscus dauricus Gebl

Common Name:
Large diving beetle

Distribution:
Widespread in Canada.

Comments:
This species is between 32 and 35 mm in length. The larvae have long, curved, pointed jaws (see figure). When they attack a prey animal they suck out its body fluids. They sometimes attack animals much larger than themselves.