Some entomologists don’t like it when people call insects “bugs” because “bug” is the proper common name of only a small percentage of insects, those in the order Hemiptera. These insects (all bugs are insects, just not the other way around) are officially called “true bugs.” (This helps distinguish true entomologists from the rest of us.) The body end of a bug’s forewing is thick and leathery; only the outboard half is membranous, and it is this feature that gives rise to the name Hemiptera, which means “half-wing.”
Bugs transform gradually from immature nymphs to adults, without the dramatic metamorphosis of many other insect orders. Young nymphs have tiny non-functional wing pads that slowly develop into wings at each successive molt.
As days cool, there’s a good chance that you can closely examine the wings or any other parts of a true bug because a couple of bug species have developed the habit of moving indoors with us. The good news is that both houseguests are large, easy to catch, and are harmless. Many bugs are predaceous, but these two species feed by sucking plant juices through tubular mouthparts and are unable to bite.
The boxelder bug has been seeking heated accommodations for many years. The western conifer seed bug is a newcomer, from the western part of the country.
True to its name, boxelder bugs feed on boxelders, though sometimes silver maples, and occasionally apples and plums are also eaten. The adults are about a half inch long, come in various shades of dark brown, have bright red wing margins, red stripes on the thorax, and red bodies. When they fly, the red body shows, and they look quite colorful. The nymphs are even redder because their small winglets don’t conceal the bright body.
Early in their development, the nymphs may feed on fallen boxelder seeds. As the nymphs and the present year’s seeds mature, the nymphs migrate to female boxelders to feed on new seeds. They also suck juices from developing buds, causing deformed leaves. Since boxelder trees are usually not highly valued, the damage is rarely lamented.
In the fall, the adult bugs become gregarious and may hold well attended meetings on the sunny sides of buildings. As the weather worsens, their interest in moving inside increases, and they seem to have a good eye for poorly fitting doors and windows.
People who hate insects get very alarmed, but the worst thing they do that I know of is to sometimes leave spots of excrement on curtains. But then, only a few have moved in to our house. Twice as many and I’d probably be reaching for the vacuum cleaner myself.
It was only last autumn that I first found a western conifer seed bug making itself at home here. It sounded like a bumblebee as it flew around the kitchen, but that’s where the resemblance to a bee ends. An even larger and more beautiful creature than the boxelder bug, it, too, is relative easy to identify as it has a distinctive delicate white zigzag line across the thickened part of the forewings. This insect is three quarters of an inch long and brightly patterned. Five black patches at the outer edge of the abdomen can be seen at the sides of the body when the wings are at rest. In flight, the rest of the abdomen, which is yellow or orange, shows up.
Western conifer seed bugs belong to the Coreidae family, also called the leaf-footed bugs, because of leaf-like extensions on their hind legs. These bugs are strong fliers, and this must have helped them expand their range in recent years, though interstate commerce may have played a role as well. Historically, they have been considered serious pests of conifers in the far western U.S. In the 1960s, they began moving east, reaching western New York by 1990 and Rhode Island in 1996.
Western conifer seed bugs may form large congregations in the fall, brought together by aggregation pheromones that are produced by both the males and females. Many insects that glom together in great masses also secrete bad smelling compounds. Clearly, if these chemicals are to deter a potential predator, the more the merrier. Having a few hundred buddies oozing malodorous fluids at the same time makes sense for small creatures such as insects.
Both the western conifer seed bug and the boxelder bug are big enough to be slightly alarming if you don’t know what they are, but as long as their numbers are reasonably small, I doubt if it hurts to keep a few of them warm and dry.