If you see what look like miniature water striders skating on the surface of a stream or pond, you may have come upon an aggregation of Broad-shouldered Water Striders, a different family of water striders from the ones we commonly see. They are tiny (2-6 mm) and very fast-moving, zipping here and there with the speed of a bullet, staying on top of the surface film, or surface tension, that is created by the attraction of water molecules. Adaptations to this mode of travel include non-wettable hairs at the ends of their legs that don’t disrupt the surface tension, and claws that are located a short distance up the outermost section of their legs rather than at the end of their legs, so as not to break this film.
Broad-shouldered Water Striders are often found in the more protected areas of a stream, where they tend to congregate in large numbers. Members of a common genus, Rhagovelia, are known as “riffle bugs” and are often found below rocks that are in the current. Broad-shouldered Water Striders locate their prey (water fleas, mosquito eggs and larvae, etc.) by detecting surface waves with vibration sensors in their legs. There can be up to six generations a summer (photo shows that they are still mating at the end of October). Broad-shouldered Water Striders spend the winter hibernating as adults, gathering in debris at the edge of the water or beneath undercut banks.
Every year I receive questions about this unusual-looking insect which is often found on and in houses in the fall. As a result, I publish a post about it every couple of years. For those of you with good memories, please excuse the repetition.
Roughly 30 years ago Western Conifer Seed Bugs (Leptoglossus occidentalis) started moving east. They are now well established coast to coast. Here in the East they seek shelter during the winter, often choosing to share our domiciles with us. Fear not – though they look fairly menacing, they will do you no harm. Western Conifer Seed Bugs do not bite or sting, and in their semi-dormant condition they do not feed or breed. If you choose not to co-habit with these bugs, be forewarned. When disturbed, they can emit a noxious smell.
In the spring they will vacate your house and feed on the sap of the young cones and flowers of conifers, including Eastern White Pine, Red Pine, Scotch Pine, White Spruce and Eastern Hemlock. Mating takes place, eggs are laid and the young nymphs feed on conifer seeds which they find by detecting the infrared radiation that the cones emit.
These bugs are also called “leaf-footed bugs,” and if you look at their hind legs you will see that a section, the tibia, is flattened. Some species display this specialized leg structure during courtship, and others may use it for defense purposes.
The Locust Borer (Megacyllene robiniae) is so-called because its host tree is Black Locust (Robinia pseudoacacia). Locust Borer larvae tunnel into a tree’s trunk and branches, weakening the tree and making it susceptible to wind breakage. In addition, these tunnels serve as a primary infection site for the wind-borne spores of the fungus Phellinus robiniae, which causes a damaging heart rot disease in Robinia species. If you see a Black Locust with many dead and broken limbs, and/or knotty swellings on the trunk, chances are great that it has been attacked by Locust Borers.
The conspicuous, brightly-colored adults appear when goldenrod is in bloom. Adults are commonly seen feeding on goldenrod pollen. Mating takes place now, in the fall, and eggs are laid in cracks, wounds and under loose bark of a Black Locust tree. The eggs hatch in about a week, the larvae bore into the inner bark of the tree and each larva makes a small hibernation cell and overwinters there. In the spring the larvae begin to bore into the woody part of the tree, enlarging their tunnels as they grow. By mid-summer they pupate and adult beetles emerge in late summer. Previously confined to the native range of Black Locust in the Northeast, Locust Borers have spread with the trees throughout the U.S. and parts of Canada.