New fruit pest discovered in North Dakota

BISMARCK – The spotted-wing drosophila (SWD), a major fruit pest, has been detected for the first time in North Dakota.

“This insect is capable of causing serious damage, and growers and gardeners should be on the lookout for the larvae in seemingly healthy fruits,” said Agriculture Commissioner Doug Goehring. “It can be confused with the common fruit fly, but SWD prefers fresh fruit while the fruit fly prefers rotting fruit.”

Goehring said the insect was found in Foster County. A sample submitted from the Carrington Research Extension Center to the North Dakota State University Plant Diagnostic Laboratory contained several cherries with SWD larvae and one adult female.

Goehring added that early detection of the insect by growers is important because symptoms do not always appear until the fruits are harvested and sometimes not until the fruits are in possession of the consumers.

An invasive pest of Asian origin, SWD (Drosophila suzukii)was first detected in the continental U.S. in California in 2008 and has since rapidly spread to other fruit-producing regions of the country. In addition to the damage caused directly by the larvae, infested fruits are susceptible to other insects, fungi and bacteria.

The SWD is a small fly, only 2 to 3 millimeters long, yellowish brown with prominent red eyes. Male SWD have dark spots on the wing tips. SWD cannot be identified without an adult specimen. The adult flies are difficult to distinguish from other small flies.

Goehring said that growers and gardeners who find an abundance of small, white maggots in what were apparently fresh fruits at the time of harvest should contact the North Dakota Department of Agriculture at (701) 328-2231 or (800) 242-7535 or the NDSU Extension Entomology at (701) 231-7064.