The wasp that could possibly get rid of the pest that has discouraged the planting of black locusts has reemerged after more than a hundred years.

Oobius depressus was found by researchers in California and Michigan after being last seen in 1914.
According to Entymology Today, Toby R. Petrice, an entolomogist with the USDA Forest Service Northern Research Station in Lansing, MI, found the wasp by placing a trap under the bark of several black locust trees, where wood-boring beetles, known as locust borers, lay their eggs.

The trap was placed at Rose Lake State Wildlife Area in Bath Charter Township, MI from August to October 2015.

The locust borer attacks the black locust tree by leaving its larvae into a tunnel dug in the tree trunk and branches, weakening the tree and making it susceptible to wind breakage. The tunnel can extend between eight to ten centimeters. As a result, the black locust tree becomes deformed or stops growing, said the US Department of Agriculture Forest Service.

The trap left by the researchers was able to catch several species. The gathered samples were sent to University of California where it was confirmed that one was indeed the reappearing wasp species Oobius depressus.

According to the researchers, identifying if it was really the Oobius depressus was not easy because the last specimen found 101 years ago in Morristown, Illinois is headless.

Nevertheless, the lab made was able to identify and then redescribe the species based on the new specimen. According to the description, the wasp is a female, with a flattened body that allows it to penetrate the trunk where the locust borer lays its egg.

The researchers said the discovery is significant because Oobius depressus might help eliminate the locust borer which damages the black locust trees that helped build the historical Jamestown, where colonists first settled in the United States.

According to Science Daily, a manuscript dedicated to the reemerging species will be published in the scientific journal of the Michigan Entomological Society, The Great Lakes Entomologist.