Forest Pests: Insects, Diseases & Other Damage Agents

Locust Borer
Megacyllene robiniae Forster

Hanson, T., and E. B. Walker. [n.d.] Field guide to common insect pests of urban trees in the Northeast. Waterbury, VT: Department of Forests, Parks and Recreation.

Coleoptera: Cerambycidae Hosts: Primarily black locust, but may also be found in honey locust and willow Evidence: Look for oozing sap beneath larval entry holes on the trunk and branches in the spring. When excavating through the sapwood, larvae push out sawdust and excrement from the entrance hole. Accumulations of this frass may be evident at the base of the tree. Larvae are white and slightly wider toward the head. They can often be heard chewing on wood. Life Cycle: There is one generation per year. The colorful adults, which are black with yellow markings, are active in late summer and early fall. They can be seen feeding on goldenrod pollen during the morning hours. Subsequently, eggs are deposited in bark crevices and wounds on host trunks. Newly-hatched larvae bore into the inner bark where they construct hibernation cells and overwinter. In the spring, activity resumes. The larvae bore deep into the wood to feed, enlarging their tunnels as they grow. By mid to late July, the larvae mature and pupate behind a plug of wood chips and frass. Adults emerge from the tunnels via their larval entrance holes.

a. LOCUST BORER adults emerge in late summer and early fall, and are often seen feeding on goldenrod pollen.

Management: Vigorous trees over 10 years old are seldom killed. Slow-growing, stressed, or young trees are especially susceptible to locust borer attack. They are physically weakened or girdled by the larval tunnels and are prone to damage by wind or other disturbances. Infested trees should be destroyed during winter or spring. If oozing sap is observed around entrance holes in spring, probe each hole with a sharp wire to kill the young larva within.

Similar Species Megacyllene caryae (painted hickory borer) adults are similar in appearance, but are active only in the spring. This species attacks black locust as well as hickory, but only recently dead or cut wood. It does not attack living trees

References:

Drooz, A.T. 1985. Insects of Eastern Forests. USDA Forest Service Miscellaneous Publication 1426. p 286-287;

Johnson, W.T. and Lyon, H.H. 1991. Insects That Feed on Trees and Shrubs. 2nd edition. Cornell University Press. p 274-275;

Rose, A.H. and Lindquist, O.H. 1997. Insects of Eastern Hardwood Trees. Canadian Forest Service Publication, Forestry Technical Report 29. p 268-269.

[ Contents ]     [ Previous ]     [ Next ]     [ Home ]