House Flies in Raspberry Bushes

What is Drosophila?

• The spotted wing drosophila is a fly that originated in Asia and has recently migrated to the United States. This fly infests stone fruits and berries, but may infest other types of fruit if they have split skins.

Identification

• This fly looks similar to house flies, but it has red eyes and a pale yellowish-brown body. There is a similar fly native to the United States, the Drosophila spp. This fly infests bananas and strawberries, but it is not known to infest raspberries. You can tell the difference between the two species by examining their wings. The male spotted wing drosophila has a small black spot near the tip of each wing. This is lacking in the standard Drosophila spp.

Damage

• The female of this species lays her eggs inside fruits. She can cut through the surface of soft fruits like strawberries and raspberries. Their offspring hatch into maggots inside the fruit, and the fruit may end up soft or rotten before it's picked. Additionally, infestations that go untreated could lead to consumers buying infested fruit.

Control and Prevention

• The application of insecticide is useful in controlling adult flies. It may require two doses made closely together to effectively eradicate them, because these pesticides will not kill the maggots while they are inside the fruit. Try malathion or pyrethroids.

  You can also manufacture traps that may capture and kill some adults. Fill a 2-liter plastic cola bottle with 12 ounces of water, 1/2 packet of yeast, 4 tbsp. of sugar and a couple of drops of dish washing liquid such as Dawn. Shake well. Cut two small entry holes about the width of a pencil in each side of the bottle about halfway down the side. Tie a string around the neck and hang it in a tree near your raspberry bushes.