By Susan Clark, who lives in Concord, in Conantum, and enjoys writing short articles on the natural history she observes around her.
For the last 5 or 6 years I have noticed these bugs in and around my house in September and October. They are handsome, seemingly harmless, rather dignified, and easy enough to evict. This year, however, I have seen dozens of them, even hundreds, and judging from phone calls and email, so have all my neighbors. This was the year to identify them!
I knew that these are true bugs, in the Order Hemiptera, the half-winged bugs. They are not beetles, which have two full sets of wings, which, when folded, completely cover their abdomens (think of lady bugs). Hemiptera have only the first set of wings, as you can see if you hold one of these bugs under a good light. Within the Hemiptera are seven suborders and 74 families; the U.S. and Canada have 45 families. The taxonomy of this huge order was revised in 1988 and seems fairly stable. But --these are large and varied families and insect field guides barely touch them.
I didn't know enough about the Hemiptera to do anything but sequential searches of my big reference book on bugs, a humbling and humiliatingly simplistic search approach. After a bit of thrashing about, I thought I had identified the family of our bugs, but was struggling to be confident about the genus. To the novice, obvious appearances can be deceiving and the Hemiptera number in the thousands. The academic reference books present the families, mention the number of genera in each family, and show a sketch of a few common species in each genus. I needed color pictures of a short list of candidates local to Middlesex County!
I was reasonably confident that our bugs are in the Family Coreidae, the Squash Bug family. There are many bugs in this family, most of them tropical; 33 genera in the U.S. and Canada and 88 species. The Coreidae are large bugs (10-20 mm), mostly brownish or blackish, elongate with parallel sides. Several of the genera have a fine field diagnostic --a segment of the back leg is distinctly flattened and enlarged, even paddle-like. The full technical jargon for this is "foliaceous hind tibiae", meaning 'with a leaf-like leg segment'. As a result the common name of these bugs is 'Leaf-footed Bugs'. The Coreidae have scent glands that stink, as some of you have discovered, when they are crushed.
In addition to the distinctive 'leaf-shaped' leg segment, Coreidae have long, 4-segmented antennae, longer than their heads but shorter than their thoraxes. The lower parts of their wings are noticeably veined (easily seen with a good hand lens). With a hand lens you can easily see two large compound eyes, as well as a pair of simple eyes.
These bugs have mouth-parts adapted to sucking plant sap, short stylus (or feeding tube) that can penetrate plant cells like a straw. A related family, the Reduviidae, with a similar body shape, has a long and more dagger-like stylus for sucking insects dry. These predators are called Assassin Bugs, an overly melodramatic name which excites the public and apparently merits the Assassin Bugs' inclusion in some field guides. Assassin Bugs occasionally bite humans in self-defense, but not for feeding purposes. Our Leaf-footed Bugs don't seem to bite, even when roughly handled. Some species are agricultural pests, including the dark gray Squash Bug, which we have in abundance in the ball field.
The Coreidae lay rows of brownish eggs in spring, which hatch in about 10 days into nymphs; the nymphs have five instars (a growth stage that ends with a molt to a larger size). At the end of the fifth instar, the adult emerges and is sexually mature. The adults overwinter, hidden under bark flaps or in Conantum houses.
I had found in my reference book two candidates, both in the genus Leptoglossus: L. clypealis and L. occidentalis. But -- L. clypealis is a pest in pistachio orchards and L. occidentalis is a western species. Unsatisfactory! But in the middle of my frustration I found a website from New York that was clearly talking about our bugs. They are in fact L. occidentalis, the Western Conifer Seed Bug. The site described the recent arrival of this bug, first described in California in 1910, then in Iowa in 1956, then in the Midwest in the 1980s. By 1994 it was found on Long Island and the lower Hudson River valley. No explanation given of its rapid expansion eastward.
The site said, "The Western Conifer Seed Bug is becoming a nuisance pest to some New York residents. The bug has the habit of entering buildings at the onset of cold weather in the late summer or early fall as it seeks a protected site to spend the winter. These bugs do not bite or sting, nor do they cause damage to the home. They will, however, give off a pungent odor if you handle them, which is part of the insect's defensive strategy." This sounds like our bug! And indeed: find a color picture of the bug top right and here.
Other photos courtesy of Art Today.
Background by Word of Mouth Web
Other photos courtesy of Art Today.
Background by Word of Mouth Web Design.