Friday, August 7, 2015
Common Water Strider
Have you ever visited a clear stream and noticed shadows passing across the pebbles and debris on the stream bed? Those moving shadows are often the first thing you see of these insects. Upon closer inspection you will see the insect causing those shadows as it moves across the water. Striders have specialized hairs on their legs that help them repel water, which allows them to glide (or stride) across the surface of the water. Their bodies have velvet-like hairs covering them which also repels water keeping them dry despite the fact that they live an entirely aquatic life.
This is a fairly large species with body lengths up to 3/4 of an inch, but with their elongated legs they look much larger, nearly the size of a quarter in diameter. Their bodies are dark brown, or black and the margins are white. All the literature I read claims the adults generally lack wings, so I assume this means there are a few individuals that may be able to fly.
To find mates they will send ripples across the surface of the water that other striders will recognize as a potential partner. After mating, females will lay eggs on the rocks, logs, water plants or other items in the water. After a few weeks the eggs will hatch and the nymphs look almost identical to the adults only much smaller. After several molts they will reach adult size and sexual maturity. Once mating season is over they will often congregate in large groups all randomly moving in circles. If disturbed they will scatter and hide in cracks, crevices or other secluded areas away from danger. Birds are fond of eating water striders and will often prey on them. Given their aquatic life, you might assume fish would eat them. This however does not seem to be the case as fish rarely consume them. Maybe they give off a defensive substance that fish find distasteful.
Even though they are harmless to humans, a bite from one of these would be a somewhat painful experience. Like most true bugs that piercing mouthpart they use to capture and kill insects can also pierce human skin and the enzyme in their mouth can cause irritation at the bite site which might result in itching or redness.
I can't think of much I enjoy more than sitting on the shore of a crystal clear stream, and listening to the birds singing, and feel the cool breezes blowing off the water and watching the water striders skate across the surface of the water with no particular place to go.