|Mushy Raspberries Infested with Spotted Wing Drosophila|
The spotted wing drosophila is a newer pest in Colorado. It was first reported in the state in 2012 and has been found in many counties. The insect is a fruit fly that attacks fruit crops including raspberry, black raspberry, strawberry, blueberry, peach, cherry and grapes. They are particularly damaging to later ripening fruit.
One difference between it and other fruit flies is that the female can lay eggs in ripening fruit. (Most fruit flies attack fully ripened fruit.) When fruit is ripe and ready to be picked, it can already be infested. That’s because the female has a sclerotized (hardened), serrated ovipositor (egg laying structure). She can pierce fruit that has not yet been softened in the ripening process. The eggs hatch into tiny maggots that quickly convert fruit into a mushy liquid mess.
Control is difficult. Fruit should be picked on a regular basis and all fruit that’s dropped to the ground should be collected and discarded. The fruit growing area should be cleaned up of debris in the fall. Insecticidal sprays are applied to the crop on a regular basis once the insect has been reported in your area. Please see this publication for suggested products. Treat crops in the early morning or in the evening when bees are less active to avoid harming them. Read the label to determine when you can harvest the crop after treatment as this varies from product to product.
|Spotted Wing Drosophila Trap|
You can make and set out traps to determine if they are present. See this fact sheet from Utah State University
which shows how to make, bait and manage a trap. While trapping isn’t a management strategy, it does take some of the adults out of circulation!
If you decide to trap, but are uncomfortable or squeamish about identifying the contents, you may bring a small bottle or jar of clean water containing the trapped insects to the Jefferson County Plant Diagnostic Clinic. (We are located on the Jefferson County fairgrounds, 15200 W. Sixth Avenue in Golden.)
Clinicians can identify spotted wing drosophila fruit flies for a $7 fee (Jefferson County residents). Out of county residents will be charged $10.