Locust Borer

Megacyllene robiniae

Classification

Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Superfamily: Chrysomeloidea
Family: Cerambycidae
Subfamily: Cerambycinae
Tribe: Clytini
Genus: Megacyllene
Species: robiniae

Pronunciation

How to pronounce Megacyllene robiniae: /ˌmɛɡəˈsɪləni ˈroʊbɪniˌi/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Images

Summary

Megacyllene robiniae, or the locust borer, is a longhorn beetle primarily affecting Black Locust trees in North America. Its larvae create significant damage by tunneling into the wood, which combined with fungal infections, can lead to the decline of these trees. Adults are commonly seen in late summer visiting flowers such as goldenrod.

Physical Characteristics

Adults can range from 11 to 28 mm in length, with a black and yellow striped pattern resembling that of a wasp or bee. The adult has a W-shaped third stripe on the elytra, dark brown to black antennae, and reddish brown legs. The full-grown larvae are legless, white, and robust, reaching about 25 mm long.

Identification Tips

Can be mistaken for wasps or bees due to coloration; distinguishing factors include its antennae length (males have longer antennae), and the presence of specific elytral markings.

Habitat

Found in uncultivated fields and meadows where Black Locust trees grow, often in association with goldenrod flowers.

Distribution

Widely distributed throughout the northeastern United States and Canada, particularly wherever Black Locust (Robinia pseudoacacia) has been planted.

Diet

Adults feed on pollen, particularly from goldenrod (Solidago spp.), while larvae feed on the wood of Black Locust (Robinia pseudoacacia).

Life Cycle

Females lay eggs in the fall, which hatch and overwinter in the bark. Larvae excavate tunnels into the tree in spring. They pupate from late July to early August, and adults emerge from late August through September.

Reproduction

Eggs are laid in crevices and near wounds of Black Locust trees. Larvae develop within the tree and exhibit a univoltine life cycle.

Ecosystem Role

Considered a significant pest affecting Black Locust trees, contributing to their vulnerability to diseases caused by fungi.

Economic Impact

Severe pest status on black locust trees can lead to economic loss, affecting timber value and overall health of plantations. Previously, their impact was so severe that timber value in the U.S. was highly compromised.

Similar Taxa

Misconceptions

Often mistaken for adult wasps or bees due to appearance, which may lead to misunderstanding of their role as a pest rather than a beneficial pollinator.