152

BYRRHOID BEETLES

BYRRHOIDEA

T

he Byrrhoidea, which is sometimes divided

into two superfamilies, Byrrhoidea and

Dryopoidea, is a varied group of 13 families of

Polyphaga (with the number of described species

as follows): Byrrhidae (430), Elmidae (1,500),

Dryopidae (300), Lutrochidae (11), Limnichidae

(390), Heteroceridae (300), Psephenidae (290),

Cneoglossidae (10), Ptilodactylidae (500),

Podabrocephalidae (1), Chelonariidae (250),

Eulichadidae (30), and Callirhipidae (150).

BYRRHOIDEA—Byrrhoid Beetles

superfamily

Byrrhoidea

known species

4,200

distribution

Worldwide except Antarctica

habitat

Varied, from mountain streams to the

canopy of tropical forests. Most species

avoid dry places

size

1–32 mm

diet

Varied, larvae and adults of many aquatic

species graze on algae and water plants.

Terrestrial larvae often in leaf litter, decaying

vegetation, or dead wood

notes

Some Byrrhoidea species are known from

huge numbers of specimens over vast areas;

others from only one or two specimens.

The largest family, Elmidae (riffle beetles), are

aquatic as both adults and larvae, with many

species found in fast-flowing, well-oxygenated

water; some species are indicators of water quality.

Adults emerge from the water on warm nights to

fly in search of new habitats, and are attracted

to lights. The same is true for other aquatic

below | Byrrhus pilula (Byrrhidae) A European Pill

Beetle is able to draw its legs and antennae into

special grooves to protect it from predators.