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The 2019 SWD monitoring network is gearing up. Cornell Cooperative Extension (CCE) will be keeping tabs on the arrival of SWD on fruit farms in New York State, primarily in blueberry and raspberry. Traps will be set in 24 counties at 37 locations with a total of 128 traps.

Picture of a Scentry trap set in a raspberry planting.
Scentry trap for SWD set in a raspberry patch.

Laura McDermott has coordinated an extensive network across 14 counties with the Eastern NY Commercial Horticulture Program (ENYCHP). She, along with Natasha Field, will be monitoring in Albany, Columbia, Montgomery, Rensselaer, Saratoga, Schenectady, Schoharie, and Washington counties. Collaborating on the ENYCHP are Elisabeth Hodgdon and Andy Galimberti in Clinton and Essex counties; Nat Mengaziol Orange county; Mike Principe in Putnam county; and Peter Jentsch, Hudson Valley Research Laboratory, in Dutchess and Ulster counties. Jim O'Connell, Ulster County CCE, will be monitoring in Ulster County.

In other parts of the state, Shona Ort will be monitoring in Chemung County; Dave Thorp in Livingston County; Don Gasiewicz in Wyoming County; Sharon Bachman in Erie County; and Faruque Zaman in Suffolk County, Long Island. On the Lake Ontario Fruit Program, Elizabeth Tee will monitor farms in Niagara and Orleans counties. Along with Ryan Parker, I (Juliet Carroll) will monitor SWD traps in Cayuga, Onondaga, Schuyler, and Wayne Counties.

Funding to support this effort comes from CCE County Associations and Regional Programs, the NYS IPM Program, and the NYS Berry Growers Association.

Growers monitoring their fruit plantings, researchers, and others can alert me of their findings,, and I'll report those on this blog.

I will also be monitoring SWD in seven tart cherry orchards in the Lake Ontario region.

SWD findings will be reported on this blog and posted to the SWD NY distribution map. Given the mild winter (except for two cold snaps...wasn't one a polar vortex?), it might be an early year for SWD arrival and build up.

Stay tuned!

Research in raspberries at Cornell AgriTech over the last four years has shown promise as an alternative tactic to reduce the impact of SWD on berries. As described in a previous blog posted in 2014, Hummingbirds, these birds may indeed enjoy eating SWD.

A trend of fewer SWD caught in traps in positions 1-4, where hummingbird feeders are located, compared to more being caught in positions 5-9, where there are no hummingbird feeders, in a transect along a raspberry planting.

Preliminary data analysis for 2018 shows that when SWD numbers are very low or very high, there is little to no difference in the number of SWD caught in Scentry traps placed in the area of the field with hummingbird feeders compared to those in the area of the field without feeders. However, when numbers are moderate, there was a difference. Along a transect down the length of the field, the trend was for there to be fewer SWD in the hummingbird feeder area compared to the no-feeder area, as shown in the chart.

The diet of an average hummingbird consists mostly of flower nectar and insects. Flower nectar provides sugar to support their high metabolic rate… even higher during flight due to their rapid wing flapping rates. The insects hummingbirds eat provide them with protein, amino acids, and necessary vitamins and minerals. The insects must be small enough to swallow whole during flight — watch out, SWD!

A grower at the SWD workshop watches as a hummingbird visits a feeder in the raspberry planting.

Two grower demonstrations were undertaken this year, as well. One in blueberry and one in raspberry. Both growers undertook cleaning the feeders and changing the sugar solution twice per week to keep the hummingbirds well fed and active within their plantings. At the workshop held in Salem, NY last month, several of the tiny birds were seen dashing about.

Placing and maintaining 25 hummingbird feeders per acre, may be a bit too arduous for some growers. This is the number of feeders we've been using in our research and grower demonstration plots and the number used by the blackberry grower in Mississippi.

Female or young ruby-throated hummingbird on a feeder set above a blueberry planting. Photo: R. Parker

Other ways to attract hummingbirds to your berry planting that don't rely on the use of feeders, would involve allocating space for flowering plants that they prefer. Interplanting with rows of Monarda (bee balm), for instance, would be one approach.

Of course, SWD is around a lot longer than hummingbirds, which have, at this point in time, likely flown off to the South on their journey to the Yucatan peninsula in Central America. Flying across the Gulf of Mexico or along Mexico's coast, they make their way to their overwintering grounds. And, as SWD populations explode in late summer, it is difficult to control SWD, let alone rely on a flying predator.

A humming"baby" feeder?

If you think hummingbirds don't eat small insects, then guess again! I've seen these contraptions showing up in stores this year — to feed hummingbirds. They are rearing capsules for fruit flies (vinegar flies, as entomologists call them). Perhaps someone should tell them we don't need more SWD? ...just more hummingbirds!


The three instars of SWD will emerge from fruit immersed in a salt solution. The smallest instar is about 0.5 mm long, the largest about 2 mm long.

Effective use of salt flotation will help you determine if your fruit are infested with SWD and if your spray program is working. It also will give you a perspective on what your customers may find when they take the fruit home to eat fresh or to make pies, jellies, jams and preserves.

I learned that variations on the salt flotation method helped a couple NY blueberry growers decide when to close this season. After a bad 2017 SWD season, when many NY blueberry growers suffered significant crop loss and shut down early, it was time to take action to monitor their fruit. Here are their methods.

Grower 1.

We analyze a batch of berries picked off bushes and a batch gathered that have fallen to the ground. Blueberries are collected randomly across our 5-acre patch. We test batches of 20-30 berries from these two sources separately and then compare.

Mix a solution of one gallon of water to one cup of salt. Place collected blueberries in two separate, labeled bags. Slightly squeeze the berries to help release larvae. Some say to give it about an hour, but in most cases, if larvae are present, they will show up in the solution as early as 15 minutes. Of course, you will want to use a magnifying device such as a jewelers loop or magnifying glass. You will see small white larvae if infestation is present.

Their results this year:

  • Aug 08:  negative, both from bushes and on the ground.
  • Aug 10:  negative, both from bushes and on the ground.
  • Aug 11:  positive, both from bushes and ground, but more pronounced with the latter.

In 2017, at least once, fruit tested positive for berries that were on the ground, but negative when picked from the bush.

Grower 2.

The salt flotation method we use is basically the same as the method demonstrated at the SWD workshops in 2014-2015. But instead of pouring the salt solution into a low tray and visualizing larvae over a black paper with a hand lens, we pour the solution through a very fine stainless steel mesh permanent coffee filter and check for larvae under a dissecting microscope. It's faster overall, and much easier to find the hard-to-see 1st instar larvae (probably to my detriment, since in the past I could ignore what I couldn't see).

We collect 100 berries randomly from throughout the planting. These are covered with salt solution (1 cup salt in 1 gal water) in a plastic bag. I don't bother pressing on the berries to crack the skins as they suggest, but gave them plenty of time to exit on their own (at least an hour, usually 2 or more).

Results this year, percent fruit with larvae, in our unsprayed blueberry planting:

  • Jul 26: 1.5%
  • Aug 3: 4%
  • Aug 9: 16.5%
  • Aug 11: 30%
  • Aug 13: 78% - in two days, the SWD numbers rose dramatically!

A male spotted wing drosophila (SWD) on blueberry, photographed in early September.

In all cases, collect what appears to be sound, perfect fruit to test for SWD infestation using salt flotation. SWD entrance and exit holes in fruit are less than half a mm in diameter and practically invisible.

I hope these two growers’ experiences using salt flotation will motivate you to monitor your fruit in this way to check for SWD infestation.

There are still a lot of delicious berries out there; lets check them and protect them from this nasty insect!


2018 SWD distribution map, showing counties where traps were being monitored.

As of August 9, 2018, all 35 SWD trapping sites have sustained catch of SWD in the 23 counties in New York where monitoring was taking place. First trap catch across the New York State network spanned 72 days, from May 22 (Erie County) to August 2 (Herkimer County). All sites used the Scentry trap and lure.

This year brought fewer reports of severe infestations to my attention, than in 2017. It may have been the hot weather, the hot winds, the cold nights in spring, the drought. Although we saw early arrival of SWD in 2018, there wasn't the rapid, consistent build-up nor the early sustained catch as seen in 2017.

High pressure from SWD always builds in late summer. Those of us continuing to monitor SWD in berries are catching 100-200 SWD per trap in the week ending August 28. SWD is likely distributed across the state and soft, late-season fruits, such as fall raspberry, late blueberry varieties, plums, peaches, and pears may be at risk of infestation. To prevent fruit infestation now, if fruit is to remain hanging for weeks to come, susceptible fruit should be protected with an insecticide program.

Protect crops from SWD- (SWD hosts)

  • late-summer-ripening raspberry, blueberry, blackberry, elderberry
  • monitor for infestation in less susceptible fruits: ever-bearing strawberries, thin-skinned grapes, peaches, plums and prunes with salt flotation

Management tactics- (SWD management)

  • timely insecticide sprays (berries) (tree fruit and grapes)
  • rotate active ingredients—read and follow insecticide label directions.
  • weed management
  • canopy management
  • clean picking
  • remove or spray dropped fruit

Find out more about SWD on the Cornell Fruit Resources SWD pages.

Please join me in thanking those who contributed time and effort to the 2018 SWD trap network!

  • Amy Ivy, CCE Eastern NY Horticulture Program (Clinton and Essex County traps)
  • Bernie Armata, CCE Association of Herkimer County (Herkimer County traps)
  • Dave Thorp, CCE Association of Livingston County (Livingston County traps)
  • Don Gasiewicz, CCE Association of Wyoming County (Wyoming County traps)
  • Faruque Zaman, CCE Association of Suffolk County (Suffolk County traps)
  • Jim O’Connell, CCE Association of Ulster County (Ulster County traps)
  • Juliet CarrollNicole Mattoon and Ryan Parker, CCE NYS IPM Program (Cayuga, Onondaga, Schuyler and Wayne County traps)
  • Laura McDermott and Natasha Field, CCE Eastern NY Horticulture Program (Albany, Columbia, Rensselaer, Saratoga, Schenectady and Washington County traps)
  • Peter Jentsch and Zayd Normand, Hudson Valley Laboratory (Dutchess and Ulster County traps)
  • Sharon Bachman, CCE Association of Erie County (Erie County traps)
  • Shona Ort, CCE Association of Chemung County (Chemung County traps)
  • Tess Grasswitz, CCE Lake Ontario Fruit Program (Niagara and Orleans traps)

As expected this late into the summer season, SWD was caught a second week in a row at a blueberry farm in Herkimer County.  7 males were caught in the traps set in and around the blueberry field, during the week ending August 9, 2018. These traps are being monitored by Bernie Armata, Herkimer County Cornell Cooperative Extension.

Checking fruit for larva with salt flotation at a workshop on SWD sponsored by the NYS Berry Growers Association.

The grower has continued monitoring for fruit infestation using salt flotation. Harvest is winding down and the farm will be closing in a few days.

If you need more information about SWD, consult the web pages listed below on Cornell Fruit Resources,, under Berry Integrated Pest Management, New and Emerging Pest Issues in Berries:

  • SWD monitoring, – describes what you can do.
  • SWD management, – describes what you should do.
  • SWD distribution, – describes where the CCE network is finding it.

Blueberry harvest is underway at a farm in Herkimer County and SWD hadn't been found. But that changed as of Thursday! Two male SWD were caught, one in each of two traps set within the planting, during the week ending Thursday, August 2, 2018. Two traps set on the edge of the planting caught zero SWD.

Only one County in Cornell's SWD Network hasn't caught SWD. SWD populations continue to build through summer and into fall, placing fruit at extreme risk.

This grower will collect a fruit sample now and test it via salt flotation to see if there is an infestation. You can do this, too! Now is the time to be checking your fruit, because SWD has been found at all but one location in the New York State SWD Network. Monitor for SWD. Protect ripe and ripening fruit crops from infestation.

Herkimer County traps are being monitored by Bernie Armata, Herkimer County Cornell Cooperative Extension.

Both sites in Chemung County are now at sustained catch. During the week ending July 27, 2018, 4 males were caught at one site with a raspberry and a blueberry planting, and 6 males and 2 females were caught at the other site in a blueberry planting. These sites are being monitored by Shona Ort, Chemung County Cornell Cooperative Extension.

Insecticide programs are in place now, which will suppress SWD population growth within the planting. In unmanaged locations, SWD numbers will continue increasing as approximately 10 generations of the insect develop during summer and early fall. A recap:

  • SWD monitoring, – describes what you can do.
  • SWD management, – describes what you should do.
  • SWD distribution, – describes where the CCE network is finding it.

Remember, the short life cycle and 10+ generations per year will make for high pressure situations in a few weeks’ time. Management, management, management…

Why does the SWD population explode?
You can do the math. Let’s think optimum conditions for SWD development. A single female can lay around 350 eggs during her lifetime, about 15 per day. The egg to adult phase of the life cycle takes as little as 6 days. So, one female in one day can result in 15 more adults 6 days later, and, during those 6 days, she will have laid another 90 eggs. 6 days after that, those 90 eggs will all be adults. Half of the 105 adults will be females, capable of laying ~350 eggs during their lifetimes…that’s 18,375 eggs or 9,187 females in about two weeks.

Meet and greet - male (right) and female (left) SWD - on a raspberry fruit.

A typical life span for SWD is 3 to 9 weeks and there are estimated to be about 10 generations per year in the US, depending on climate. Back to the one female. Let's say that she lays 70 eggs per week and, when she dies in 5 weeks she's laid 350 eggs and, by then, about 280 of those are adults. Half of those adults, 140, are females and, by then, have laid 49,000 eggs, 29,400 of which will, by then, be adults. Half of those adults, 14,700 are females and, by then, have laid 3,087,000 eggs ...I'm lost and I probably made a mistake...but you get the idea - over 3 MILLION in five weeks from ONE (really from two, because you need a male and a female).

After a very early first catch in late May, SWD has again been caught in Erie County. Re-catch occurred the week ending July 12, 2018, when two female SWD were caught, one each in traps on the edge of and within the blueberry planting. Seven SWD were caught the subsequent week, ending July 18, three females in the edge and three females and one male within the planting.

Traps at this location are being monitored by Sharon Bachman, Erie County Cornell Cooperative Extension.

Blueberries are ripe across the region and harvests are underway. Once again, it’s time to pay attention to SWD and protect ripe and ripening fruit crops from infestation.

SWD found in Dutchess County, as of the week ending on July 10, 2018, and sustained catch during the week ending July 17.  On July 10, four females and one male were found in the raspberry crop, and three females and two males were caught in the nearby hedgerow. On July 17, only 1 female was found in the traps set in the crop and one female in the hedgerow.

Female SWD, on left, has large ovipositor. Male SWD, on right, has a spot on each wing.

Interestingly, the number of SWD caught decreased significantly from the first week to the second week possibly indicating that effective management tactics were put into place at this location.

SWD needs to be managed in susceptible fruit — know if it's on your farm and know how to fight it!

The traps in Dutchess County are being monitored by Zayd Normand, summer intern, working with Peter Jentsch, Hudson Valley Research Laboratory.

A blueberry grower in Tioga County monitoring traps daily for male SWD in their planting caught 6 males in one day, July 21, 2018. No SWD were found in traps up to and including Friday, July 20th.

Homemade SWD trap. The red cup contains an apple cider vinegar drowning liquid and a specimen cup with a wheat dough bait. Traps are checked daily for males.

The two traps are set in the hedgerow adjacent to the blueberry field. To quote the grower,

"Spraying is going to be hard with wet weather for the rest of the week."

The blueberry grower is making their own traps, using whole wheat dough as the bait and apple cider vinegar as the drowning liquid. Instructions for these whole wheat dough traps are on the SWD Monitoring page.

Only two Counties reporting zero SWD trap catch (gray) - Herkimer and Orange - as of July 23, 2018.


Elsewhere, across the CCE SWD monitoring network, all locations have reported in. Only the sites in Orange County and in Herkimer County have yet to catch SWD. Dutchess and Erie Counties are now at sustained catch. Details of these findings will be reported in a separate blog.

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