Coleoptera- the beetles


Art: C. Ruth Neudahl
Text: Valerie Brady

Note the size of the real penny and use it to judge the size of the bugs in the following pictures.

Family: Dytiscidae, Predacious Diving Beetles

Dystisid beetle-adult

Class: Insecta

Order: Coleoptera, the beetles

Family: Dytiscidae, predacious diving beetles

Size: Larvae: 0.2 B 2.5 inches (5 B 70 mm); adults: 0.1 B 1 inch (3-25 mm)

Habitat & Habits: Larvae and adults live in lakes, ponds, and sometimes streams. Larvae cling to vegetation or crawl among rocks. Adults are fast swimmers, using their hind legs like oars. Most larvae and adults must come to the surface for air.

Feeding: Larvae ("water tigers") and adults are voracious predators, and catch quite large prey for their size, including small fish.

Water Quality Indicator: Because Dytiscidae are more common in ponds and lakes, and because both adults and larvae breathe air, these beetles are not considered particularly informative of stream water quality.

Family: Elmidae, Riffle Beetles


Class: Insecta

Order: Coleoptera, the beetles

Family: Elmidae, riffle beetles

Size: Larvae and adults: 0.05 - 0.5 inches (1-12 mm)

Habitat & Habits: Most species of riffle beetles live in gravel and rocky bottom areas of swift current in streams. Larvae have hard bodies. Both larvae and adults crawl slowly among the rocks and gravel, using claws to cling. Adults rarely fly and are primarily aquatic.

Feeding: Larvae and adults eat algae and detritus.

Water Quality Indicator: Riffle beetles are moderately intolerant to tolerant of nutrient pollution.