Entertaining Surface Insects

     Every niche on Earth has its community of creatures, even the surface tension of water here in southeastern Pennsylvania, as throughout the world.  Water strider bugs and whirligig beetles inhabit surface tensions of ponds and slow-moving parts of streams, the striders more on streams and the whirligigs more on ponds.
     Water striders and whirligigs both have flat, dark, half-inch bodies, are active in the warm temperatures of summer, predatory on spiders and other kinds of insects, lay eggs on stones and plants on the bottoms of waters, and entertaining to watch on water surfaces, particularly when there are several of one kind or the other in gatherings of themselves.  Both species are easily seen with only a little looking for them.  Sometimes I see the shadows of these insects on the bottoms of streams and ponds before I see the critters themselves.  Being insects, both species have six legs and two wings that grow from their thoraxes.  And the legs and bodies of both kinds are adapted to their niches and ways of life.
     Water striders ski on the surface tension of water because of their long legs and feet that distribute their weight across the tension, making dimples on the water's surface, but not breaking it.  The front pair of legs of each strider grabs prey animals.  The second pair rows or propels each strider across the tension and the third pair spread their weight over a lot of water so each insect doesn't break the water's surface.  It's interesting to watch these insects that are so well adapted to water surfaces, ski or skate on top of it.
     Each water strider has a long, firm mouth that pierces and sucks.  Each strider finds prey by its front feet feeling ripples in the surface tension from insects and spiders struggling on the surface.  Each strider skates up to the prey animal, pierces it with its mouth, injects its enzyme-filled saliva into the victim to break down its body cells and sucks out the resulting liquid.  And, in turn, water striders are preyed on mostly by a variety of birds.
     When courting, male striders rhythmically tap the water surface with their front feet to send out ripples (signals) that females, and rival males, feel with their front feet.  Receptive females respond back and their suitors mount them.         
      I think whirligig beetles are even more entertaining to watch than water striders, especially when several whirligigs are together in a mass.  I have to chuckle when I see them.  Whirligigs live IN the water surface rather than on top of it like the striders.  Therefore, whirligigs have different adaptations for their life style than striders do.  Like striders, whirligigs' two front legs grab tiny invertebrates, but their back four legs are short, flattened like paddles and strong for swimming.  These beetles are superbly streamlined, and each eye is divided so that the upper part of each one sees above the surface while the lower part of each eye can see below the surface at the same time.
     Whirligig gatherings on the move on the waters' surfaces, with our imaginations, form letters and figures that rapidly appear and disappear.  Each beetle is fast in the water and zips around, often in circles, like a tiny speed boat.  And groups of them together zoom among each other without collision.  Sometimes they form tightly-packed masses on the surface.  Then the outer beetles try to push their ways toward the middle of each congregation.
     Water strider bugs and whirligig beetles are entertaining on or in the surfaces of water during warmer months.  When fishing, picnicing or whatever by a pond or slow stream, look for these predatory, interesting insects.  They help make the day more enjoyable.