Backswimmers are insects classified as “true bugs” and belong to the order Hemiptera. Most Hemipterans are land dwelling, such as stink bugs and assassin bugs, but there are a few, such as water striders, water boatmen and backswimmers, that are aquatic. In the fall, when most insect hatches have ceased, backswimmers come into their own. While some hibernate at the bottom of ponds in winter, others remain active, sculling through the water with their oar-like hind legs that are covered with fine hairs, preying on all forms of life up to the size of a small fish. Thanks to bubbles of oxygen that they obtain from pockets of air just under the ice and carry around with them like mini aqua lungs, backswimmers can continue to stay below the surface of the water for several minutes. Like most aquatic insects, backswimmers supercool their bodies (produce antifreeze compounds called cryprotectants that allow their body fluid to go down to 26 to 19 degrees F. without freezing). Right now, when there’s a thin layer of ice on most ponds and no snow covering it, you might want to peer through the ice at the edge of the pond to see if you can locate any of these cold-hardy creatures. Just be sure you don’t fall in, as I did two seconds after this photograph was taken. My undying gratitude for those of you who have donated to Naturally Curious, as your support enabled me to replace both camera and lens!
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Backswimmers are aquatic insects that seek out prey as large as tadpoles and small fish. They row around ponds with their fringed hind legs and grasp prey with their front pair of legs. The piercing mouthparts that they use to kill their prey are also capable of giving humans who handle them carelessly a nasty bite (they are also known as “water wasps” for this reason). Because they spend most of their time on their back, their coloring is opposite that of most insects – backswimmers typically have a dark belly and a light-colored back, making them less conspicuous to predators (and prey) both above and beneath them. These tiny bugs can stay submerged for hours thanks to their ability to store air bubbles in two channels on their abdomen which are covered with inward-facing hairs. Backswimmers are often confused with Water Boatmen, which are not predaceous, do not bite, and swim “right side up.” Water Boatmen’s dark color and parallel lines on their backs help distinguish them from Backswimmers.
Grass of Parnassus, also known as Bog-star, is a favorite flowering plant of mine for two reasons. One is because I enjoy saying its name — try it, it sounds quite regal. Secondly, the green lines, or bee guides, on the petals are a striking color which you don’t see all that often in flowers. Grass of Parnassus is in the Saxifrage family – not in the Grass family, as its name would imply. It typically grows in wet meadows. Apparently the name comes from ancient Greece; the cattle on Mount Parnassus ate this plant with relish, and thus it was deemed an “honorary grass.” (An Ambush Bug is perched on a petal, waiting and watching for prey.)
The Spined Soldier Bug is a predatory stink bug which preys on a variety of other insects (over 90 species), especially the larvae of butterflies, moths and beetles. It is one insect that farmers actually welcome, as it preys heavily on the larvae of the European corn borer, Mexican bean beetle, cabbage looper, Colorado potato beetle, flea beetles and many other crop pests. The adult Spined Soldier Bug has a prominent spine on each “shoulder.” It also has piercing-sucking mouthparts which it uses to impale prey and suck out their internal juices. The photograph shows a Spined Soldier Bug dining on the innards of a monarch caterpillar.
This time of year you can often find many orange and black bugs on milkweed leaves. If they are black with an orange “X” on their forewings, they are small milkweed bugs (Lygaeus kalmii). This combination of colors, which many insects that feed on milkweed have, warns predators that, due to ingesting milkweed toxins, red and orange insects may be bad for their health. Adult small milkweed bugs feed mainly on milkweed seeds, but they also consume the nectar of a variety of flowers. In addition, they occasionally prey on insects, such as the ant in the accompanying photograph.
Ambush bugs, assassin bugs, leaf-footed bugs and stink bugs are in the order Hemiptera – they are true bugs. Although all insects are often referred to as “bugs,” technically, only insects in this order are considered and referred to as bugs by entomologists. All true bugs have piercing and sucking mouthparts, and wings which are membranous and clear at the tips, but hardened at the base. Ambush bugs are actually a type of assassin bug, most of which are predators. Ambush bugs are usually brightly colored (yellow, red or orange) and they also have thickened front legs, resembling those of praying mantises, which are used to capture prey. If you carefully examine goldenrod flowers, you will probably find some well-camouflaged ambush bugs, waiting motionless for prey to come to them. Thanks in part to their impressive front legs, they are capable of capturing prey ten times their own size. At this time of year you can also find mating pairs, as in this photograph.