Water Striders are hard to catch, but Jessie, from Hester School in Farmersville, caught this one in the dry creekbed. He had to act fast because striders are fast in and out of water. After being handled by a few of us, the strider was glad to be free when Jessie released him before leaving the preserve.
Water striders, or pond skaters, are gregarious semi-aquatic insects that live on the water surface. Most species prefer quiet waters in small coves, ponds or lake margins; a few species inhabit small, flowing streams. This family contains the only insect genus to adapt to life in the open ocean. Water striders are common throughout California. They have been collected from sea level to 8,500 feet.
Water striders belong to the insect order Hemiptera (true bugs), family Gerridae. In California there are five Gerrid genera, Gerris, Halobates, Limnoporus, Metrobates and Trepobates. Eleven species of water striders occur in California, most belonging in the genus Gerris.
Water striders vary from 1/4 to 1 inch in length. Most species are dark colored or reddish brown. A few species have gray yellow or silver markings. The head of a water strider possesses two widely separated compound eyes, a pair of long slender antennae and a long recurved beak. Their front legs are short and raptorial. The middle and hind legs are spindly and used for locomotion with the middle pair the longest. The tarsi (last leg segments) have fine hairs that are hard to wet, enabling water striders to be supported by the surface film. The body of water striders is covered with fine velvety hairs (hydrofuge). In the genera Gerris and Limnoporous the body is elongate. In the genera Metrobates, Trepobates and Halobates the body is short and broad with a flattened abdomen. The presence of wings vary with each species. In a given population most individuals do not have wings, some have partially developed wings and a few possess fully developed wings.
Water striders are very active insects. They are commonly seen skating, running or jumping across the water surface. They have the ability to leap a short distance into the air to catch small flying insects.
Not all their time is spent on the water surface. Some species can leave the water, walking on the shore or resting on rocks and other objects. In response to adverse conditions, some adults can fly to new habitats.
Water striders are highly predaceous, feeding on a variety of aquatic insects. Foreleg hairs are sensitive to surface vibrations, allowing them to detect the location of potential prey. Once captured the prey is held in the forelegs and a digestive enzyme is injected. After the prey's body contents are dissolved, the water strider sucks it dry.
To avoid predation water striders have developed three
defense mechanisms: (1) diving beneath the water surface, (2) distasteful
secretions, and (3) death feigning (remaining rigid for 10 - 15 minutes).