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Phylum Arthropoda
Class Insecta
Order Hemiptera
Family Pleidae
Common Name Pygmy Backswimmer
Distinguishing Characteristics
  • Oval, plump with a concave back
  • Compound large eyes with ocelli vestigial
  • Short and weak antennae which are usually carried tucked to the head
  • Effectively flightless group
  • Hindless are hairless and appear ill-suited for swimming
Additional Pictures
     There are 37 species in 3 genera; 2 generas are found in North America. The family can be found worldwide with the exception of the polar regions and remote oceanic islands. Adults range in length from 2-3 mm. Their preferred habitat is vascular aquatic plants in standing water. As predatory hunters, Pleidae consume the body fluids of small invertebrates.

     Pleidae are completely harmless to humans as their rostrum is far too small to pierce skin. Their hind claws enable them to clamber through vegetation which apart from swimming is their main form of locomotion. They are in an upside-down position while swimming. Pleidae are air-breathers and carry an air reserve with them which is periodically replenished by a dash to the water's surface. This air is contained in a felt-like cushion on the underside. Thus the belly has a higher buoyancy.

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Additional Links



Merritt, R W., K W. Cummins, and M B. Berg. An Introduction to the Aquatic Insects of North America. Dubuque, Iowa: Kendall/Hunt Company, 2008.

"Family Pleidae – Pygmy backswimmers." Bugguide.Net. 1 February 2010. Iowa State University Entomology. 16 May 2008 <http://bugguide.net/node/view/49815>.