Length: 4-5 mm
The Water Penny Beetle family has only five genera in North America. The family is named for the larvae, which are in the shape of flattened disks and which cling to rocks in the water.
The male Ectopria nervosa (shown here) has strongly serrate antennae, while the female antennae are only moderately serrate. Also, the eyes of the male are noticeably larger than those of the female.
Right: A lateral view of the same individual. The beetle was climbing a stalk next to a shallow backwater of a medium-sized stream.
Ectopria nervosa vary somewhat from individual to individual, which led to the description of many "new species" that later had to be merged back into Ectopria nervosa. The female was even described as a separate species from the male!
Insects of West Virginia