Black Stem Borer – Xylosandrus germanus

Black Stem Borer (Xylosandrus germanus) Latin Name: Black Stem Borer Common Name: Xylosandrus germanus Appearance: The adult female is a compact and slightly hump-shaped glossy black beetle with a hooded head and mouthparts pointing downwards, measuring about 1/12-inch (2 mm) in length. The male, somewhat smaller and lighter in color than the female, has rudimentary hind wings and, unlike the female, does not fly. The mature female is a small, hump-shaped glossy black beetle with a hooded head and downward-directed mouthparts. The male is somewhat smaller and lighter in color than the female and has rudimentary hind wings but does not fly. Eggs: A female may lay up to 54 eggs depending on the host, although the usual clutch size is 18; eggs are tiny (1 mm), white, transparent, glossy, and football-shaped. Larvae: The whitish, sturdy, and slightly curled grub-like larvae have visible mandibles but no identifiable head.They move slowly and undulatingly; it is typical to discover all phases of the insect living in the same chamber. Larvae go through three stages. Pupae: Pupation happens after a prepupal period of 2–3 days; freshly pupated individuals are white, but the eyes, mandibles, and wings darken and become recognizable within two days. It takes around 30 days for an egg to develop into an adult. Host plants: Xylosandrus Germanus, sometimes known as the Alnus ambrosia beetle, is an invasive Asian beetle that was accidentally transported into central Europe and North America. Territory: The black stem borer, Xylosandrus germanus, commonly known as the Alnus ambrosia beetle, is an invasive beetle from Asia mistakenly introduced into central Europe and North America. Damage caused by Black Stem Borer: The mature female of the ambrosia beetle, X. Germanus, bores 1-mm-diameter holes into the trunk to construct galleries in the heartwood of stressed, dying, or recently dead trees’ trunks and branches. During the larval and adult phases, Ambrosia beetles are fed by a symbiotic fungus carried by the adult female in a mycangium, an internal pouch on its back. Life history and Habits: The adult female is a compact and slightly hump-shaped glossy black beetle about 1/12-inch (2 mm) in length. The male, somewhat smaller and lighter in color than the female, has rudimentary hind wings and, unlike the female, does not fly. In New York, this species has two generations each year and overwinters as adults, usually females, in host plant galleries. The mature female is a small, hump-shaped glossy black beetle with a hooded head and downward-directed mouthparts. The larvae look like grubs. After 2–3 days of temperatures over 68°F (20oC), the first bugs emerge. They are white, strong, and somewhat curved, with prominent mandibles but no different heads.