Megacyllene robiniae, commonly known as the locust borer, is a species of longhorn beetle endemic to eastern North America.

From a distance, M. robiniae can easily be mistaken for a wasp or bee, due to its black and yellow striped pattern.

The full grown larvae are legless, white, and robust, growing to roughly 25 mm (0.98 in) long.

The females are often found running up and down black locust trunks in search of wounds in which to lay their eggs in the fall.

These tunnels are around 10 cm (3.9 in) long by 7 mm (0.28 in) wide, and serve as a primary infection site for wind-borne spores of the fungus Fulvifomes robiniae, which causes a damaging heart rot disease of Robinia species, causing them to be more susceptible to wind damage.

Were it not for these beetles and their larval tunnels promoting fungal infections, it could be one of the most valuable timber trees that could be planted in the northern and middle states; young trees grow quickly and vigorously for a number of years, but soon become stunted and diseased, and rarely live long enough to attain any commercial value.