Department of Environmental Conservation

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Beetles (Coleoptera)

General Information about Beetles (Coleoptera)
Life history Some kinds of aquatic beetles live their entire life cycle in the water, other kinds spend their larval life stage in the water, and some other kinds spend their adult life stage in the water. Beetles undergo complete metamorphosis (egg, larva, pupa, adult).
Diversity There are about 23 families of aquatic beetles in North America.
Aquatic larvae: head is thick and hardened; no wing pads present, single tarsal claw (nail); some have long filaments at the end of the abdomen, some have visible structures along the sides of the abdomen, and most have hardened skin.
Aquatic adults: hard body, wings covered by hard shell-like cover and are not veined, the sides of the cover create a center line along the back.
Habitat & Feeding Different kinds of aquatic beetles can live in a variety of habitats: lakes, ponds, slow-moving water, fast-flowing streams, marshes, and marine or brackish water. Aquatic beetle larvae and adults may be: scrapers (eat algae off rocks), collector-gatherers (eat fine organic material), collector-filterers (eat fine organic material collected from the flowing water), or predators.
Water quality indicator status Some kinds of aquatic beetles (larvae and adults) need specific environmental conditions. They also have a range of sensitivity to pollution and/or environmental stress caused by human activities.
Fun facts
  • The Whirligig beetle's eyes are divided into two pairs: one above and one below; this allows the beetle to see predators above and below the water surface.
  • A highly specialized group of aquatic beetles is able to obtain oxygen from air spaces within submerged aquatic plants by piercing the plant with a spine on their tail.
Image of adult Elmidae, riffle beetle.
Adult Elmidae beetle.
Image of larvae Elmidae (riffle) beetle.
Larvae Elmidae beetle.

image of Haliplidae beetle
Family: Haliplidae
image of water penny
Family: Psephenidae