Synonyms and other taxonomic changes
Megacyllene robiniae (
J.R. Forster, 1771)
Explanation of Names
Latin for "of Robinia". Robinia is the genus of trees which includes the Black Locust.
Identification
Adult beetles are black with yellow stripes across. The third stripe on the elytra is W-shaped.
Habitat
Anywhere Black Locust trees are present - most of the US.
Season
Adults most noticeable in September when Goldenrod comes into bloom.
Food
Larvae feed exclusively on Black Locust tree and its cultivars (Robinia pseudoacacia). Adults feed on pollen, particularly Goldenrod (Solidago).
Life Cycle
Eggs are laid in locust trees in the fall. Newly emerged larvae spend several months in tree trunks, first hibernating through the winter under the bark, then tunneling into trees in spring, eventually making tunnels about 4" long and .25" inch wide. They pupate late July/early August. Adult beetles emerge late August to September (click on the Data tab for a graphic confirmation of that fact).
Remarks
Considered a serious pest of Black Locust trees; previously weakened or damaged trees are often killed by an infestation of the larvae. Previously confined to the native range of Black Locust in the northeast, it has spread with the trees throughout the US. Unfortunately Black Locust is used for reclamation and similar projects where trees are likely to be stressed out and thus more vulnerable to insect damage.
See Also
Megacyllene caryae, Hickory Borer, which is active as an adult in the spring, rather than in the fall as this species is. Larvae feed on hickory and pecan.
Megacyllene decora
Placosternus
