Crawling Water Beetle

Family: Haliplidae

Genus: Peltodytes

Pictorial Key
Size: 2mm-4.5mm
Threadlike Antennae
The Haliplidae Family of beetles is characterized by its oval shaped body that tapers towards the end. There are over 60 species and 4 genera occuring in the eastern United States.It is generally 1.5-4.5mm in length. The hind coxae (attachement of hind legs to ventral side of the abdoment) are large, covering up at least two abdominal segments in almost all species. These hind coxae are used for air storage while the beetle dives underwater.
The head of the Haliplidae is small and the antennae are threadlike and short. Haliplidae swin well in quiet still water.  They are most commonly found in ponds, lakes, and streams and even along the banks of running water. The long hairs on the hind legs allow them to swim effectively. Adult Haliplidae feed on algae and small aquatic animals.
The species pictured here is in the Peltodytes genus. It contains 15 species which are widely distributed throughout the United States, fairly common, and 4-5mm in length. Haliplus is distinguishable from the Peltodytes genus in the fact that its hind coxal plates are not bordered by a groove and reach only the 3rd abdominal segment. Peltodytes have grooved coxal plates and coxal plates that reach the base last abdominal segment.