Megacyllene robiniae

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Megacyllene robiniae
M robiniae.jpg
Adult locust borer
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera
Suborder: Polyphaga
Superfamily: Chrysomeloidea
Family: Cerambycidae
Subfamily: Cerambycinae
Tribe: Clytini
Genus: Megacyllene
Species: M. robiniae
Binomial name
Megacyllene robiniae
(Forster, 1771)
M robiniae nativedis.png
Native range
  • Megacyllene flexuosum (Fabricius, 1775)
  • Megacyllene pictus (Drury, 1773)

Megacyllene robiniae, commonly known as the locust borer, is a species of longhorn beetle endemic to eastern North America. It is a serious pest to Robinia pseudacacia, the black locust tree, with which it is sympatric.


The specific name, robiniae, is derived from the New Latin name, Robinia, which is the generic name of the black locust tree, Robinia pseudacacia, on which the larvae feed. The name, Robinia, was coined by Linnaeus to honor the royal French gardeners Jean Robin (father) and Vespasien Robin (son).


From a distance Megacyllene robiniae can easily be mistaken for a wasp or bee. Even at a closer look it is often mistaken for M. caryae or M. decora. The adult beetle grows between 12 and 20 mm (0.47 and 0.79 in) and has a W-shaped 3rd stripe on the elytra. The antennae of both sexes are dark brown. The male's antennae are two-thirds its body length, and the female's are one-half. The legs are reddish-brown.

Geographic range and habitat[edit]

Its geographic range has grown over the years following the expanding range of R. pseudoacacia. As more and more people use the black locust tree as an ornamental, the range of M. robiniae grows. It can be found almost anywhere unprotected black locust trees grow, and is often more abundant when Solidago, commonly called goldenrod, is also present. The females are often found running up and down black locust trunks in search of wounds in which to lay their eggs. Both sexes are most common from late day to dusk. Because of the adults' primary food, they tend to stay in uncultivated fields and meadows.

Life cycle[edit]

Adult on Solidago

Adults lay their eggs in locust trees in the fall. Later the larvae will hatch and spend the winter hibernating within the bark. Once winter ends, the larvae will burrow into the tree trunk and start to tunnel. These tunnels are around 10 cm (4 inches) long by 7 mm (0.25 inch) wide. The larvae will then pupate in late July and early August. The adults will start to emerge in late August and throughout September.


Adults feed on pollen of goldenrods of the genus Solidago. The larvae feed on the wood of Robinia pseudacacia.

Pest management[edit]

There is currently only one registered product in use, Carbaryl, which is effective against M. robiniae. It is applied in a single dose when adults are most active (August/September).[1]