The Elm Seed Bug, belonging to an order of bugs called Hemiptera – or “true bugs”, is related to Boxelder Bugs and Stink Bugs, and often mistaken for both. They look very similar to a Boxelder Bug, but are much smaller in size: Adult Boxelder Bugs are about 1/2″ long, whereas adult Elm Seed bugs are only 1/4-1/3″ long. In their immature life cycle stage, Elm Seed Bugs can also be mistaken for bed bugs as they are quite red in colour.
Elm Seeds Bugs feed primarily on the seeds of Elm Trees, as their name suggests, however they have been known to feed on other types of tree seeds as well (e.g. oak trees).
Elm Seed Bugs are classified as a nuisance pest, as they do not cause damage to trees or structures, and do not pose a health threat to humans. Calling Elm Seed Bugs a nuisance may be putting it lightly, however, as the sheer number of Elm Seed Bugs that can gather in one place (such as in someone’s home) can be offputting at best and alarming at worst.
Elm Seed Bugs mate during the spring and lay their eggs on Elm Trees. The immature Elm Seed Bugs – called nymphs – feed on the seeds from spring, into early summer, and grow into adults. Elm Seed Bugs will overwinter as adults, staying in a dormant state through the cold, winter months.
Elm Seed Bugs are most noticeable in the springtime when they emerge from overwintering; as well as in the peak of summer, and again in the fall. During the hottest months, Elm Seeds Bugs will attempt to escape the heat by entering homes and other structures; and they will enter structures once again in the fall as they search for overwintering sites.
Unlike the Boxelder Bug, Elm Seed Bugs produce an unpleasant, pungent odour when disturbed or crushed – so resist the urge to do so!