How to identify a water strider

How to identify a water strider

Often seen floating on top of still water, the water strider will glide effortlessly supported only by its thin hair-like legs. At first appearance, one might think that the water strider has only four legs but it is a known fact that all insects have six. The other pair of legs on the strider is short and pulled up beneath its head. From time to time this hidden pair of legs will touch the water surface and at other times they do not.

Since the water strider used the four longer legs for movement the front legs as used exclusively for capturing and holding its prey while it feeds. Water striders are known to have two distinct types of movement with one being the gliding motion that is created by using the middle legs in a rowing fashion while the back legs trail behind. The second motion is a quick jump which is often seen as this insect pounces on its prey. This motion is made by using both pairs of the back legs.

The water strider uses the gliding motion to orient itself on the waters surface as it moves toward other insects. It is able to detect its prey on the surface of the water by the tiny rippling motions the prey generates on the waters surface. Water striders are able to pick up the vibrations of their prey with tiny sensory organs in their legs and after they have rushed to the prey they will grab it with the two shorter front legs.

Once the prey is captured the water strider jabs its beak into the insect and pumps juices into it that first stun the prey, then begin to dissolve its insides. Once the inside of the prey is completely dissolved it is sucked out by the water strider and the remaining skin is discarded. During the spring and through early fall the water striders carry on many interactions as the mating and egg-laying season occurs. It begins when the male locates a stationary object that is suitable for egg-laying.

This might be planted in the water, a bit of wood but both the male then lures the female to the nest. Both remain at this spot making a tiny rippling pattern by moving their middle legs up and down rapidly. Researchers believe that two different patterns are used. One to lure a receptive female and the second to warn other males not to approach too closely. The male water striders defend these sites, even attack other males that come to close.

When the mating is complete the female will lay the eggs in parallel rows as the male remains near to protect her with ripple signals or direct attack. Females are known to produce around three broods per year. The nymphs will usually hatch in around two weeks, after which they swim to the surface where they must learn to break through the waters tension to move on top. Nymphs will go through five molts before becoming adults.

There are two common genera of water striders. The Gerris and Metrobates. These insects are from the Gerridae family and in the order of Hemiptera which also means half wing bugs. Gerris is known to have long, thin bodies that in some cases reach a half-inch long or longer and can be found in still waters. Metrobates tend to have bodies that are short and stout, getting no more than a one-quarter inch long.

This genus prefers living in fast-moving streams on the surface of the water. When looking at the water strider in a clear stream their shadow makes it appear that they have pads on each leg but this is caused by indentions in the water from the insect’s weight.

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