Batesville Herald Tribune, Batesville, Indiana

August 27, 2013

Invasive fruit fly found in Franklin County


The Batesville Herald-Tribune

---- — The spotted wing drosophila, an invasive fruit fly, has been positively identified in Franklin County by the Purdue Extension office in Brookville. Ag and natural resources educator Anna Morrow answered a call concerning small white worms in blackberries that were only noticeable when the fruit was cooked. The blackberry canes and berries appeared normal, until the client went to make jam from the berries.

Research into the matter led her to believe that this was spotted wing drosophila, a pest native to Asia, which was first detected in North America in California during 2008 and in Indiana last fall by the Purdue Extension office in Blackford County.

Morrow explains, “SWD cannot be positively identified by larva alone, so I needed to trap adult flies to confirm that Franklin County was indeed dealing with SWD. Traps made out of plastic cups using apple cider vinegar for bait caught several fruit flies. These flies were sent to Purdue and identified by a U.S. Department of Agriculture Animal and Plant Health Inspection Service insect identifier.”

SWD are particularly harmful to small fruits because they are able to lay eggs in intact fruit, unlike native fruit flies. Soft-skinned fruits such as blackberries, raspberries and blueberries are at higher risk for SWD. Female SWD make a tiny cut into fruit that is just beginning to color and lay their eggs inside during late summer. As the fruit ripens, the eggs hatch and larvae eat the fruit. It is nearly impossible to tell if eggs have been laid inside the fruit until the larvae have done their damage. SWD will also lay eggs in strawberries, cherries and grapes.

Cultural control of this pest includes removing and destroying overripe fruit to prevent larvae from developing into adults. Removing wild host plants that can harbor SWD, such as wild grape, pokeberry, honeysuckle, nightshade, dogwood, spicebush, autumn olive, raspberry and blackberry, may also help control the flies.

There are several registered conventional insecticides that are effective against SWD. “Remember to always read and follow label directions,” she advises. For recommendations or more information, persons may contact Morrow at 765-647-3511 or annamorrow@purdue.edu.

Morrow points out, “This is another way that the extension office is working to inform Franklin County residents of important issues. The identification of this new and worrisome pest was made as part of a routine call to the extension office. If you suspect an invasive pest or have other questions, please contact the office.”