Skip to content

SWD populations are building up. Of the 44 locations where traps are being monitored for SWD, 29 (66%) have reported SWD trap catch. Over half of these locations have caught SWD two weeks in a row with SWD numbers caught now in the teens. Sixteen locations in Albany, Cayuga, Genesee, Niagara, Ontario, Rensselaer, Schuyler, Ulster, Wayne and Yates Counties are at sustained trap catch—two weeks in a row. Monitoring for first catch of SWD is nearing completion for 2015 and traps are being pulled from the monitoring network.

SWD populations are increasing in neighboring states and provinces, too. Reports from Ontario Province and Maine, Massachusetts, and Rhode Island align with our findings in New York State. If you are in affected counties, take measures to protect your fruit crops – insecticide programs, sampling fruit, sanitation, and postharvest refrigeration will all assist in protecting susceptible fruit.

Be proactive with your customers. Let them know about SWD and what you are doing to combat it. Tell them to refrigerate the fruit they buy.

Reports of SWD eggs and larvae are coming in from our research and Extension colleagues. You can check for fruit infestation using a salt floatation test. Follow these methods:

  • Prepare salt water – 1 cup salt per gallon of water.
  • Collect perfect fruit. Fruit should be sale-able, not soft or overripe. (25 large – strawberry, plum; 50 medium – large-fruited blueberry or blackberry; 75 small – small-fruited blueberry or raspberry.)
  • Put fruit in a gallon size re-sealable plastic bag.
  • Pour salt water into the bag to cover the fruit.
  • Mark bag with field code and date.
  • For a quick check in the field – after 15 minutes, hold the bag up to light. This helps to see the larvae that emerge from the fruit into the salt water.
  • For a more thorough examination – after 15 minutes, pour the fruit and salt solution into a shallow tray and use a piece of wire mesh screen to hold the fruit down or sieve it to separate the larvae in the salt water from the fruit. Larvae are more easily seen against a dark, black background. The better the lighting, the easier it will be to see the larvae, so plan to be in a well-lit area with minimal glare.

NOTE - A light infestation, or one with mainly 1st instar larvae, will be difficult to see with the naked eye. Use a magnifier, loop, hand lens, optivisor, or dissecting microscope for easier viewing. Another approach is to split the fruit sample into two parts – do salt floatation on one part and hold the other part in a container at room temperature and do salt floatation on it after three days.

First instar larvae are < 1 mm long. Third instar, fully grown larvae are 2-3 mm long. SWD larvae (Drosophila suzukii) are indistinguishable from larvae of the common vinegar fly (D. melanogaster.)SWDlifecycle

A video on salt floatation in the field, produced by Peerbolt Consulting, Pacific Northwest, can be found at:

If an infestation is found in your planting, clean pick all ripening, ripe and overripe fruit into clear re-sealable bags. Kill the SWD in it by freezing it or solarizing it and dispose of it. Pick up or step on and crush any fruit that has dropped to the ground. Protect the unripe fruit with insecticide sprays applied at 5 to 7 day intervals. This practice will protect the green and unripe fruit from the SWD that would have developed in the infested fruit in the planting and dropped on the ground.

If your berry planting is small and can be framed over, consider the use of exclusion netting to protect fruit next year. This may be worth the investment to preclude the need for routine insecticide applications.

Four male and 10 female SWD were caught on Monday, July 27, 2015 in traps set in red raspberry in Monroe County. All four traps at the site caught SWD. For berry crops that are at risk of infestation, it will be important to plan a spray program and sanitation program to protect ripening fruit. Cool fruit (32-33 F) as soon as possible after harvest to delay or stop development of SWD. This information, and more, is available on the SWD Management page on Cornell Fruit Resources.  (GDD = 1590, day length = 14:40)

Four female SWD were caught on July 23, 2015 in traps set in black raspberry in Wyoming County. One trap had 1 and the other had 3. Traps are being monitored by Don Gasiewicz, Cornell Cooperative Extension of Wyoming County. (GDD = 1167, day length = 14:44)

A lone female was caught in a trap set in blueberries in Washington County on July 22, 2015 by Laura McDermott, Eastern NY Commercial Horticulture Program. (GDD = 1543, day length = 14:48)

SWD female caught in a Livingston County raspberry planting the week of July 18 to 24. The characteristic saw-tooth ovipositor is shown in the inset, upper left. Note the thin dark bands on the abdomen.
SWD female that drowned in apple cider vinegar in a trap. The characteristic saw-tooth ovipositor is shown in the inset, upper left. Note the thin, continuous dark bands on the abdomen.

One female was caught on July 20, 2015 in a trap set in a raspberry planting in Orleans County and being serviced by Liz Tee who works with Debbie Breth in the Lake Ontario Commercial Fruit Program. Although the count is very low at this site, some locations are reporting trap catches in the double digits now. Protect berries, grapes and tree fruit that are ripe and ripening. Pay attention to all practices that can be used on your farm to manage SWD. (GDD = 1382, day length = 14:53)

Four male and one female SWD were caught in traps set in Ulster County and checked on July 15, 2015 by Jim O'Connell, Ulster County Cornell Cooperative Extension & the E NY Commercial Horticulture Program. One male was caught in a trap set on the edge of a blueberry planting and the rest were in a trap set in raspberries. (GDD = 1309, day length = 14:52)

Two males and one female were caught in traps checked on July 15, 2015 by Liz Tee who works with Debbie Breth in the Lake Ontario Commercial Fruit Program. The traps were set on the edge of a red raspberry planting in Niagara County. (GDD = 1211, day length = 15:00)

One male was caught in a trap set in raspberry and one female was caught in a trap set in blueberry in Livingston County. Traps were checked on July 15, 2015 by Dave Thorp, Livingston County Cornell Cooperative Extension and the insects identified by Nicole Mattoon, NYS IPM Program. (GDD = 1150, day length = 14:58)

Three females and one male were caught in a trap set in a summer raspberry planting at a farm in Albany County. Traps were checked on July 15, 2015 by Laura McDermott, Eastern NY Commercial Horticulture Program. (GDD = 1312, day length = 14:56)

Skip to toolbar