Skip to content

As I sat one evening enjoying my glass of Cabernet Sauvignon on my patio in the Finger Lakes, I noticed several small fruit flies flitting about my wine. Hmmmm...yes, SWD. The tell-tale spots on the wings of the males were a dead giveaway. And I've grown so used to the golden brown somewhat hunchbacked body of the females, that I knew who they were. Red wine is known to be highly attractive to SWD, as is Concord grape juice. Both have been used as baits and drowning solutions in SWD traps. Although, I'd rather not waste wine in an insect trap.

Photo of an SWD on a wine glass.
SWD on a wine glass can ruin your summer evening.

This week Grace Marshall and I are doing a final check of the traps we have in our research plots. Last week, on average, we were catching 20 to 1000 SWD per trap in the summer raspberry and blueberry plantings with nary a fruit in sight. Counting the SWD in those traps is no small task. I was finding myself seeing spots — literally, SWD wing spots — the day after counting. One trap had 3022 SWD in it. In most of the traps the majority of fruit flies in them are SWD — upwards of 95%.

A photomicrograph showing numerous male and female SWD that were caught in a trap.
On the left, males, and on the right, females, counted on June 20, 2020, caught in an SWD trap set in a tart cherry orchard.

Our trap catch data from these berry plantings, confirms findings by other researchers that traps on the crop edge that are near woods catch more SWD than traps set within an insecticide-treated planting. Plantings that are surrounded by open fields, row crops, and roadways tend to have fewer SWD overall, as compared to plantings with wooded edges or ponds, streams and ditches nearby.

As populations of SWD continue to grow across the region, be aware that unprotected, susceptible fruit is at very high risk of SWD infestation, especially if allowed to hang until soft and ripe:

  • blackberry
  • fall raspberry
  • day neutral or ever-bearing strawberry
  • elderberry
  • peach and nectarine
  • plums and prunes

Fruit, such as peaches, nectarines, plums and prunes, that aren't highly susceptible to SWD may escape infestation even without insecticide treatment if harvested before they are fully ripe and soft. All will benefit from cold storage. Keep up on your SWD management tactics. Review the information on the SWD Management page of Cornell Fruit Resources,

Overall, still a quiet week for SWD trap captures in the Lake Ontario region's tart cherries. Although SWD was caught across the region, only 2 at most in the two traps set per orchard. Traps were checked Monday and Tuesday, June 15 and 16. Elizabeth Tee and Janet van Zoeren, Lake Ontario Fruit Program, and Grace Marshall and Juliet Carroll, NYS IPM Program, are participating in this study along with nine fruit growers.

In our 11 study orchards, SWD has been caught in 5 of the 6 “lake” blocks and in 3 of the 5 “inland” blocks. Specific trap catch results for this week were:

  • Zero SWD in six orchards out of 11.
  • First catch in one orchard = 1 female in edge trap.
  • Recatch in three orchards = 1 male in edge trap; 2 females in edge trap; 1 male & 1 female in interior trap. Each orchard had one week with zero SWD between first catch and this week’s catch.
  • Sustained catch in one orchard = 1 male in interior trap this week and 1 male in edge trap last week.

SWD populations were still low over the past week in tart cherry orchards. What can we credit with keeping SWD populations low, so far? Some possibilities include:

  • Choosing insecticides that are also effective against SWD for other key cherry insect pests such as plum curculio or the Rhagoletis fruit flies (cherry fruit fly, black cherry fruit fly, European cherry fruit fly).
  • The dry weather and low humidity.
  • Lack of alternate fruit resources in the wild, due to freeze events.
  • Slow progression of fruit development, due to the cold spring.
  • Possibly the cold weather last week and cold nights lately.

Populations are low in berries, too, in western NY. This past week, SWD was only caught in one of the 12 berry sites in the Lake Ontario, Finger Lakes, and Central NY regions that we are monitoring.

Cherry fruit is starting to color.

Be watchful of your crop's development. Now is the time to plan your SWD management strategy so you have a good selection of rotational insecticides to protect your crop through to harvest.

Picture of Juliet Carroll, NYS IPM Program, servicing an SWD trap hung in a tart cherry tree.
Juliet Carroll checks a SWD trap in a tart cherry orchard to help determine the need to spray, as fruit ripen.

For cherry fruit fly management (Rhagoletis spp.), choose insecticides that also have activity against SWD to keep the population down and protect your fruit from Rhagoletis fruit flies. Refer to the SWD Insecticide Quick Guide for tree fruit and grapes Cross-reference this with the Cornell Pest Management Guidelines for Commercial Tree Fruit Production. Select insecticides wisely. 

SWD can lay eggs in ripening cherries. If SWD has been caught in your orchard, ripening and ripe cherries will be at risk of SWD infestation. Pay close attention to preharvest intervals (PHI) and plan insecticide use so you have materials with lower PHI for use close to harvest. Rotate IRAC groups for resistance management. Drosophilids are known to develop insecticide resistance. Follow label directions. Be wise.

SWD management tactics

  • Mowing – to reduce humidity and niches for SWD harborage and to increase sun penetration. Research has shown this works in tart cherry orchards in Michigan.
  • Weed management – to reduce humidity, alternate fruiting hosts and harborage and to increase sun penetration.
  • Pruning – to reduce humidity and to increase sun and spray penetration. Research has shown this works in tart cherry orchards in Michigan. Improve your pruning strategy this winter.
  • Monitoring – to know if SWD is present when fruit is ripening. Don't spray unless SWD is caught. Some years your crop may not need a targeted program for SWD.
  • Sanitation – to reduce reproduction harborage and overall SWD population. Important in diversified fruit farms.
  • Cold storage – to slow or kill any eggs and larvae in harvested fruit. Not applicable for a processing crop harvested into water tanks. SWD won't survive in water tanks; larvae may float to the surface or fruit may float higher because the infestation changes their buoyancy.

Bookmark online resources

This week, ending 1 June 2020, first catch was obtained in 4 of 11 tart cherry orchards in the Lake Ontario region. Add to that another orchard that had first catch the previous week (no catch there this week) and we're at almost half of the orchards, especially those within a mile of Lake Ontario, with SWD detections. SWD is starting to show up, though not so much in the berry plantings being monitored across New York. The months of June and July are typical first catch months, so stay tuned — to this blog and also to the ripening of your fruit crops.

Photo of a male SWD taken through a dissecting microscope.
This male SWD was caught during the last week of May in a trap set in a tart cherry orchard. Note the shape, size and position of the characteristic spot on each wing.

Janet van Zoeren, Liz Tee, and Grace Marshall are assisting me with this work in tart cherries. Janet and Liz work in the Lake Ontario Fruit Program of CCE. Grace works in the NYS IPM Program of CCE.

If you grow tart cherries or sweet cherries, keep in mind both these tree fruit crops are susceptible to infestation by SWD when its populations build up near your orchard prior to harvest. It has been shown to be good practice to monitor for this insect in cherries. If you find SWD in your orchard as fruit is ripening, you need to protect the crop with insecticide sprays. If you don't find SWD when fruit is ripening, you don't need to spray and can save a bundle of money.

How to thwart the build up of SWD populations in cherries?

Insecticide choices:

  1. Choose plum curculio insecticides that also have activity against SWD.
  2. Choose cherry fruit fly insecticides that also have activity against SWD.

...a pattern is emerging in this suggested approach.

Cultural tactics:

  • mow to keep the orchard floor drier, less humid, and less favorable to SWD.
  • prune to open the canopy to more air circulation, faster drying, better spray penetration: drier, less humid, and less favorable to SWD.

...a pattern is emerging in the proven research.

Get your 2020 Cornell Pest Management Guidelines for Commercial Tree Fruit Production, from here or from the CCE LOF or ENYCH Program you belong to.

Learn more about SWD on the Cornell Fruit Resources SWD webpages,, and on the NYS IPM Invasives & Exotics webpages,

Let knowledge be your best weapon.

All is quiet in the berry plantings in the SWD monitoring network - no SWD found to date. However, in tart cherry orchards in Wayne County, a single SWD has been caught in three of seven orchards where Carroll is conducting research on this insect. In two of these orchards, this is the second week a single SWD was caught, so we are at sustained trap catch. Though, thankfully, numbers are still very low, fruit is green and unsusceptible, and needed plum curculio and cherry fruit fly insecticide sprays in tart cherry orchards will knock back SWD populations.

This is proving to potentially be an early year for SWD arrival and we will continue to monitor. The cool, humid and wet weather following a relatively mild winter may have promoted better overwinter survival of SWD and fostered sustained early spring populations.

While the insecticide quick guides haven't been updated as of yet, they are still current as we know of no new materials, at least in New York, that have been labeled for SWD management. Take a look at our management resources, and plan accordingly, SWD Management.

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!


We have caught SWD at all but one of the seven tart cherry sites we are monitoring in Western NY, Wayne and Ontario Counties. Counts are still low and it is likely that the hot and dry weather, as well as insecticide protection, has held things in check. Weather has turned cooler and rains have brought needed water to crops – SWD will like this, too.

Our low numbers are in stark contrast to the high numbers of SWD being reported this week by Nikki Rothwell, Michigan State University, in traps set in Michigan tart cherry orchards.

NOTE: First trap catch of SWD signals it’s time for insecticide protection in tart cherries. And... most berry sites in the statewide SWD monitoring network are now at sustained catch!

Trap catch results for tart cherry sites close to Lake Ontario in Wayne County:

  • Two are at continuous catch – third week in a row.
  • One has had discontinuous catch – SWD caught three times, but with intervening weeks with zero catch.

Trap catch results for tart cherry sites inland in Wayne and Ontario Counties:

  • One is at sustained catch.
  • Two are at first catch.
  • One has had zero SWD catch to date.

Cherries are ripe and soft and harvests are getting underway. Orchards in Western NY that have been harvested or will be harvested soon should escape SWD infestation without significant insecticide expense. If harvest won’t occur for another week or more, insecticide protection on the crop needs to be maintained at 7-day intervals; immediately reapplying after rain wash off.

A 50-fruit sample was collected this week from all the orchard blocks in which we have traps and checked via salt flotation. One of the samples had evidence of SWD eggs, no larvae. All other samples had no SWD in them.

Here’s the blog link for the tart cherry SWD insecticide and SWD management info, which I posted last week:

If, after harvest, there is remnant fruit on the ground that might put nearby cherry orchards or berry plantings at risk, consider a single application of Asana XL (2ee) on the fruit remaining on the ground (see quick guide to insecticides for treating dropped fruit). Keep in mind that the dropped fruit would have insecticide residue on it, so any application to dropped fruit should be delayed to take advantage of that residual insecticide coverage.

SWD was caught in three of seven tart cherry orchards we are monitoring, during the week ending July 6. All three of these sites are near Lake Ontario in Wayne County. Inland sites in Wayne and Ontario Counties have yet to catch SWD.

Harvest dates were projected to be one to three weeks out. However, the heat of late has brought fruit to ripeness faster than expected. Fruit is at high risk of infestation because it is now ripe and soft. We will continue trapping at these sites through harvest.

For SWD management in Michigan tart cherries, monitoring with SWD traps is used to determine when SWD is in the orchard. Once SWD is found, it is time to initiate a spray program to protect tart cherries, regardless of the number caught.

Collecting a Scentry trap to check for SWD in a tart cherry orchard.

The seven orchards we are monitoring have two Scentry traps in the block, one in the interior of the block (In) and one on the edge of the block (Out). Here are the numbers for each of the three sites:

In: 1 male; Out: 1 female

In: 1 female; Out: zero

In: 4 females; Out: 2 females

Mostly females were caught — a somewhat typical pattern, wherein females are caught first.

For best results, sprays should be applied at 7 day intervals. If it rains, apply an insecticide as soon as possible after the rain. Refer to the insecticide quick guide for tree fruit.

A recap of efficacy (days-to-harvest) for insecticides labeled for use on tart cherry against SWD; strikethrough on materials with likely too long a preharvest interval.

Excellent – Exirel (3 days), Minecto Pro (21 days), Danitol (3 days), Mustang Max (14 days), Imidan (7 days)

Good to Excellent – Entrust 80WP 2ee (7 days), Entrust 2SC 2ee (7 days), Asana XL 2ee (14 days), Lambda-Cy EC 2ee (14 days)

Moderate – Delegate WG (7 days)

Fair to Poor – Grandevo (zero days) This biological may prove useful in close rotation (3 days) with excellent materials, such as Entrust to bring you up to harvest. This is how it is being used in commercial blueberry production in NJ.

Other management tactics to consider:

Mowing row middles every other week was found to significantly reduce SWD infestation over no mowing in Michigan. Trees were unsprayed and 3 gallons of fruit sampled at harvest for SWD larvae showed, on average, 100 larvae in unmowed orchard setting versus 25 in the mowed orchard; a 75% reduction.

Test fruit pressure? In plums, if fruit was greater than 3.5 lbs pressure it wasn’t susceptible. If less than 3.5 lbs pressure it was susceptible to SWD.

Most counties reporting in the SWD network have zero SWD captures (gray color) as of June 6, 2018.

As of 6 June 2018, no new reports of SWD trap captures in raspberry or blueberry from across the network have come in. All the NYS IPM Program's traps checked so far this week in tart cherry had zero SWD, including the site that had two females last week. In a research site where we are monitoring 36 traps in 1.5 acres of raspberries, zero SWD have been caught. Very low populations of SWD and no sustained catch has occurred to date.

Above, on the right, is the latest New York State distribution map built from data entered by the SWD monitoring network participants.

Tart cherry fruit development as of June 4, 2018. Not susceptible to SWD oviposition and infestation at this stage.

June strawberry harvest will begin this week, but the low numbers of SWD caught to date indicate low to no risk to this crop, so far.

In the Finger Lakes, Central NY and Wayne County, raspberry are just beginning to bloom.

Blueberry fruit have set, but are still green and hard.

Tart cherry are also still hard and green.

Hard, green fruits aren't susceptible to SWD infestation and don't warrant insecticidal protection.

Two female SWD were caught in two traps, one in each trap, in a tart cherry block near Lake Ontario's shore in Wayne County during the week ending on May 31, 2018. This tart cherry block had significant SWD infestation in 2017. Fruit are still hard and green in this block and are not yet susceptible to SWD.

Five other farms we are monitoring in Wayne County and one in Ontario County had zero SWD caught.

Reviewing 2017 tart cherry spray records from several farms in the Lake Ontario region showed (1) spray intervals were long, between insecticides effective against SWD, as harvest approached; and (2) blocks with 14- to 30-day-long spray intervals that escaped SWD injury were harvested before SWD either arrived or had built to damaging population levels.

In Michigan tart cherries, where SWD has been problematic for several years, the tactics are to (1) monitor for SWD in the tart cherry orchard; (2) keep an eye on fruit ripening stage, blush signals susceptibility; (3) apply insecticide to protect susceptible fruit if SWD has been caught in the orchard.

In an effort to spare your spray bill, be mindful of the other insects you are targeting in your tart cherries and choose insecticides that will also prove effective against SWD. The SWD insecticide quick guide for stone fruit is available on Cornell Fruit Resources Spotted Wing Management page.

If you're targeting plum curculio, consider using Exirel, Asana, Imidan, or Minecto Pro. If you're targeting cherry fruit fly or black cherry fruit fly, consider using Delegate, Exirel, Asana, Imidan, or Minecto Pro. If you're targeting obliquebanded leafroller, consider Entrust, Delegate, Exirel, Danitol, or Minecto Pro.

Be aware that only a couple materials effective against SWD for tart cherry have short, 3-day, pre-harvest intervals: Exirel (only 3 applications per year) and Danitol (only 2 applications per year). Grandevo, a biological has zero days to harvest and has been shown to be a good rotational product with Entrust in organic systems against SWD in blueberry. Make sure you plan a spray program that will spare these crucial short pre-harvest interval materials for use as harvest approaches.


In the last week of July 2017, my program found up to 100 SWD in some of the SWD traps in our raspberry research plot in Geneva, NY. Without a doubt, pressure from SWD and fruit infestation levels will be increasing as the SWD population explodes.

Sampling cherries in 2016 in western NY to check for SWD. None was found, but in 2017 the situation was different.

In addition, fruit crops normally escaping infestation are reporting problems with SWD. Early blueberry varieties are at high risk and the later varieties will be even more prone to infestation. A tart cherry grower in the Lake Ontario region reports a load of fruit rejected by the processor due to SWD infestation.

When harvest dates are close to insecticide application dates, the available insecticides that can be used against SWD on berries or on tree fruit are few because of the needed days-to-harvest intervals. The heavy rains washing off applied materials creates a greater challenge to keeping fruit clean of infestation.

A mild winter; early arrival of SWD; warm, cloudy, rainy weather; abundant fruit; prolonged ripening windows — these likely have created a perfect storm for SWD in 2017. We continue to learn about this pest, what drives it, and what we can do about it. We thought summer raspberries, early blueberry varieties, tart cherries and sweet cherries weren't at high risk, perhaps we need to rethink this in light of this year's situation and be more vigilant in 2018 for conditions that favor SWD infestation in our early fruit crops.

Skip to toolbar