The Spotted Wing Drosophila (SWD) is an invasive species of fruit fly that is native to eastern Asia. Since it was first detected in the western US in 2008, it has been making steady inroads across the country. It is already considered a major crop pest in Maryland and is set to earn that title in many more states. Careful monitoring of this fly is important not only in the management of individual crops, but as a step in understanding the movement of and developing a response to these insects. If you think you have them in your area, please contact your local Cooperative Extension for more information on best practices for controlling them.
This fly is often referred to as a vinegar fly and is very similar in appearance to the common vinegar fly. Careful identification of any flies found is recommended so that the SWD is not mistaken for the common vinegar fly, which is considered a nuisance pest as opposed to a crop pest. One major difference between the two is that the common vinegar fly is drawn to over-ripe, fermenting or rotten fruit and the SWD will seek out healthy fruit to lay eggs in. With this propensity for healthy fruit and their ability to reproduce quickly, it is easy to see how they can become a big problem around fruit crops.
- Raspberries, late cherries, blueberries, peaches, plums, thin-skinned grapes and fall strawberries are the preferred hosts for SWD.
- SWD adults go after ripening fruit beginning in July and their numbers peak in September or October. The timing of this may vary according to geographical location, cultivation practices, weather and other factors. SWD is not a problem until the fruit starts to ripen, so begin your monitoring whenever that begins to happen.
- SWD will prey upon wild hosts before they move onto cultivated crops, so if you live near an area that is home to wild fruits you will want to keep an eye on them as they begin to ripen. This will give you a head's up to protect your crops.
- Comes with illustrated instruction to assemble the trap and add lure.
These traps and lures are meant only as monitoring tools, if you find SWD on your crops you will need to use insecticides to get rid of them. Please refer to our Suggested Products at the bottom of this page for some excellent choices.
WHERE TO PLACE THE TRAPS –
It is best to set up the traps in the shade amongst the foliage of your crops.
CHECKING THE TRAP –
Check traps at least once a week, but during the warmest months you should check more often. Continue monitoring until fruit is harvested.
ASSEMBLY AND USE INSTRUCTIONS –
- Remove lid and wire hanger combo from jar.
- Add drowning solution to jar (1⅔ cup). Drowning solution can be water with a couple of drops of unscented liquid dish detergent. Some people add borax or sodium benzoate as a preservative.
- The SWD lure will hang inside the top portion of the trap. Slide lure onto wire hanger through grommet on lure.
- Pull hanger up and insert end through second hole in lid. Pull hanger until it seats fully into the lid. You may hear a click, indicating the hanger is seated.
- Screw lid, hanger and lure combo onto jar. Hang using wire hanger.
HOW MANY TRAPS WILL BE NEEDED –
The general rule is 2 traps for most plantings and 3 or more for very large plantings. However, the number of traps you will need depends on several variables such as whether you have more than one crop that is susceptible, or different varieties that ripen and are harvested at different times. If in doubt as to how many you need to use, please contact your local Cooperative Extension for guidance.