Pleidae

Common Name

Pygmy backswimmers

Overview

Pleidae, commonly known as pygmy backswimmers, are a family of aquatic bugs that belong to the order Hemiptera and suborder Heteroptera. These minute insects are widely distributed in freshwaters across the globe, where they play an ecological role in the aquatic ecosystem.

Taxonomy

Key Characteristics

  • Size: Extremely small, typically 1.5 to 3 mm in length.
  • Body Shape: Oval and somewhat flattened body, adapted for swimming.
  • Coloration: Generally yellowish to dark brown.
  • Legs: Hind legs modified for swimming, similar to oars.
  • Wings: Presence of fully developed wings; capable of flying but rarely observed doing so.
  • Eyes: Large, well-developed compound eyes, relative to their body size.

Life Cycle

  • Egg: Eggs are laid on submerged vegetation or other underwater surfaces.
  • Nymph: Nymphs resemble adults but are smaller and lack developed wings. They undergo several molts before reaching adulthood.
  • Adult: Reach maturity and are capable of reproduction.

Behavior and Ecology

  • Habitat: Found in a variety of freshwater habitats including ponds, lakes, and slow-moving streams.
  • Diet: Predatory; feed primarily on small aquatic invertebrates such as mosquito larvae and other tiny organisms.
  • Swimming: Use their hind legs to propel themselves under water, often swim upside-down.
  • Breathing: Obtain air through a specialized system of air storage under their wings, allowing them to stay submerged.

Notable Species

  • Neoplea striola: One of the better-known species, observed in North American freshwater bodies.
  • Paraplea puella: Found in various regions, including parts of North America and Europe.

Conservation

Most species in the Pleidae family are not currently considered to be threatened or endangered. Their small size and widespread distribution help them evade many large-scale environmental threats.

Significance to Humans

  • Ecological Role: Important in controlling mosquito populations by preying on larvae, thus indirectly benefiting human health by reducing the numbers of these disease vectors.
  • Research: Serve as model organisms in studies on aquatic insect behavior and physiology.

Fun Facts

  • Pygmy backswimmers are among the smallest aquatic insects.
  • Despite their tiny size, they are effective predators in their ecosystems.
  • They can store a bubble of air under their wings to help them stay submerged for extended periods.
  • Their swimming motion involves rapid, synchronized kicking of their hind legs, much like human swimmers using the butterfly stroke.