Gerris lacustris Pair Insect Water Strider True Bug Hemiptera Heteroptera Gerridae

Gerris lacustris Pair (male + female) cm 1-1.7 Insect Water Strider Skeeter Scooter Skipper Skimmer True Bug Hemiptera Heteroptera.
Family: Gerridae.
Common name: The Common Pond Skater or Common Water Strider.
Syn: Aquarius lacustris.

The Gerrids or skating insects are a family of Rincoti (Hemiptera) Heteroptera of the superfamily Gerroidea (Gerromorpha). They owe their name to the ability to "slide" on the water by placing only the tarsus of the middle and hind legs on it without sinking.
The middle and hind legs are arranged in an X shape forming a quadrangular support plane centered with the center of gravity of the body; the anterior ones, on the other hand, are shorter, more robust and visibly extended forward. This morphology is at the basis of the functionality of the legs: the front ones are used as raptorial legs, while the middle and rear legs are used for support. The propulsion is instead ensured by the medium legs.
The Gerrids are dipping or semi-aquatic insects. In other words, they are basically terrestrial organisms but closely associated with aquatic environments, as their life takes place largely on the surface of bodies of water (streams, lakes, ponds, swamps and even seas). In general, they prefer calm or slightly wavy waters, but they can also adapt to running waters. In this case they proceed in the opposite direction to the current, maintaining the position and giving the impression that they are stationary.
The Gerrids feed mainly on small animals, live or dead, which they find on the surface of the water or immediately below, also contributing to the containment of the populations of mosquito larvae, therefore they must be considered useful organisms in all respects. In predation they use the front legs to grab and hold the victims, which they then pierce with the mouth apparatus to paralyze them and suck their internal fluids.
They have a moderate gregarious instinct, so they usually come in more or less numerous groups. Population density in relation to food resources is fundamental, because in case of scarce availability they easily resort to cannibalism. This aspect is important for breeding enthusiasts, as it is difficult to keep many specimens in an aquarium without them killing each other.
The ability to be able to support oneself with the legs on the surface of the water without sinking is due both to the physical-chemical phenomena (surface tension) that regulate the static balances of the intermolecular forces in the interface surfaces and to the chemical and morphological properties of the legs of the legs. , the only points of contact and support of the insect's body with the surface of the water. The legs are covered with a thick down soaked in oily water-repellent substances. This means that the water does not "wet" the legs, a necessary but not sufficient condition for them to immerse themselves in the water. The relatively light weight of these insects, together with the water-repellent nature of the tarsi, means that the Gerrids and insects with similar properties, rest on the free surface of the water without penetrating it.
Unlike other Gerromorphs, such as the Veliidae and the Hydrometridae, the Gerrids are endowed with an exceptional speed, thus giving the impression that they "skate" on the water; this movement proceeds in jerks, under the effect of the propulsive thrust of the middle legs and the sliding on the water. In the movement it seems that the legs of the same pair move simultaneously. This speed also makes them capable of escaping any pitfalls and, in fact, the capture of a Gerrid requires a certain patience even with the use of a net: in a colony of Gerrids, in fact, it seems apparently easy to capture one or more specimens. in a puddle of water but, in reality, at the slightest hint of danger, the insects quickly escape by sliding on the water with abrupt changes of direction.
On the dry, the Gerrids have rather clumsy movements, proceeding with irregular and uncoordinated jumps.