A species of
wasp1 that is a natural enemy of a wood-boring
beetle2 that kills black
locust3 trees has been rediscovered, more than 100 years after the last wasp of this species was found. The discovery is significant because the wood-boring beetle, known as the locust borer, is considered a serious pest that has discouraged planting of black
locusts4, which played an important role in American history. The trees, whose wood is strong, hard and extremely
durable5, helped build the Jamestown settlement and were featured prominently at George Washington's Mount Vernon.
The only previous known
specimens6 of the wasp (Oobius depressus) date back to 1914 and were found in Morristown, Illinois. The problem with those specimens is that they were missing their heads and
antennae7, making them difficult to identify even by specialists of that wasp family, Encyrtidae.
That led Serguei V. Triapitsyn, director of the UC Riverside Entomology Research Museum, and Toby R. Petrice, an entolomogist with the U.S.D.A. Forest Service Northern Research Station in Lansing, Mich., to search for new specimens.
This was not an easy task because eggs of locust borer, particularly ones parasitized by this wasp, are extremely difficult to find. Adults of the locust borer itself, on the other hand, are common in the Midwest in early fall because they feed on the
pollen8 of goldenrod.
Because females visit black locust trees to lay eggs, the scientists placed an insect trap designed to collect
beetles9 and other
arboreal10 insects in the
canopy11 of a black locust tree at Rose Lake State Wildlife Area in Bath Charter Township, Mich., from August to October 2015.