Creature Feature
Backswimmers
by Gary Winans
In just about any pond or pool you can find backswimmers: small, oval bugs
about a half-inch long, with one pair of long legs extended out and angling
towards their heads. The long legs are used like oars and propel the insect
forward in sharp jerks, rather than in a continuous, smooth movement. If you see
them hanging at the surface, they are either searching for prey or replenishing
their oxygen (nymphs, or immature forms, must do so every five minutes, while
adults can remain underwater for hours). Backswimmer Sketch - two views
Backswimmers are carnivorous, eating other insects, tadpoles, small fish and crustaceans. Researchers believe that backswimmers detect their prey by feeling vibrations made in the water by the other creature. Once the prey has been caught by the front legs of the backswimmer, it inserts its beak-like mouth and pumps digestive juices into its victim, dissolving the insides. The backswimmer then sucks out the digested innards. Yum, yum - insect milkshakes!
To observe a backswimmer more closely, you can catch one, put it in a small container with some water and view it through a hand lens or observascope. If you ladle the water out until it is very shallow, the backswimmer will turn over and you can see its back, which is white. But take care not to handle the backswimmer with your bare hands its bite can be painful!