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SMALL DIVING BEETLES

DYTISCIDAE: HYDROPORINAE

DYTISCIDAE: HYDROPORINAE

subfamily

Hydroporinae

known species

2,200

distribution

Worldwide except Antarctica

habitat

Ponds, pools, rivers, and streams, with

a few species found in cave systems or

subterranean aquifers

size

1–8 mm

diet

Adults and larvae are predators of other

aquatic invertebrates, and may also

scavenge on dead organic matter

notes

A few Hydroporinae, such as the genus

Geodessus from India, have left the water as

adults and instead live like ground beetles in

leaf litter. Some other species are even more

H

ydroporinae is the largest subfamily in the

diving beetle family Dytiscidae, but includes

some of the smallest diving beetles. They are

distinguished from other subfamilies by the absence

of a visible scutellum, characteristic segmentation

of the tarsi (feet) in adults, and by larva having a

long, hornlike projection in the center of the head,

which, together with the mandibles, is used for

catching and restraining prey. Like other

Dytiscidae, adults and larvae are predators,

usually of small worms or insect larvae.

The aquatic larvae of Hydroporinae

swim well, and crawl out of the water

to pupate in the soil or sand on the

bank. The adults of most species

can fly, especially those that

depend on temporary pools.

Hydroporinae occur

throughout the world, but

species are usually closely

associated with specific habitat

types, from temporary rain pools

to large lakes. Generalist species

are often among the first beetles to

colonize new water bodies, such as

rain-filled tire tracks or even paddling pools.

In more complex environments, numerous

below | Hydroporus palustris This

widespread Eurasian species renews

its air supply at the water surface.