WSU Tree Fruit Research & Extension Center

Spotted Wing Drosophila

Monday, March 25, 2019

SWD Project Logs for 2013


Saturday, August 3:

Attention SWD trappers/cherry growers:  I would like to collect populations of SWD from Washington cherry orchards to start colonies.  Please contact me ( or cell 509-679-1010) or Pete Smytheman (; 509- 630-6526) if you have an orchard we could collect from. 

Wednesday, July 10:

10 July 2013.  With harvest either complete or in full swing, it’s easy to forget about cherry pests…but don’t do it.  The challenging weather this season has made it extremely difficult to get sprays on, and to keep them on.  Splits and wind damage are also very prevalent issues, providing an easy entry for drosophila pests.  The numbers of drosophila finds in the warehouse to date already exceeds the total found in 2012, and more are still coming in.  Of those larvae we have been able to rear, all were SWD (even though Drosophila melanogaster can also attack damaged fruit).  Please note:  the trap counts of SWD are still low.  While you are out there, don’t forget about western cherry fruit fly.  If harvest is extended, consider using GF-120 to get you through.  While GF-120 will do a little good for SWD, it is not complete protection. 


If fruit harvest is over, and you left a lot of fruit on the tree, consider a post-harvest clean up spray for both pests.  Imidacloprid will do a good job on cherry fruit fly (mediocre on SWD); dimethoate will be effective on both.  Dimethoate is phytotoxic to cherries; read the label carefully.

Friday, June 7:

Zillah positive for SWD: A trap sample from the Zillah region was found to contain SWD today.

Friday, May 31:



All but one region has found SWD in at least one trap, so we are willing to declare that this pest is active throughout Eastern Washington at this point.  We are moving rapidly toward harvest in the early districts, and fruit become susceptible as they ripen.  As your crop reaches the blush stage, we have sufficient evidence that they are susceptible – so keep your crop covered once you reach this maturity stage, regardless of where you are located, or what the trap in your orchard has caught.


Things do seem to be heating up (in terms of SWD) a bit earlier than last year, despite a cool, rainy spring.  This pest has had 3 seasons to become firmly established in our region, and this (plus the absence of severe winter temperatures) may be the reason for the earlier activity.  Remember, this is the first year that we have recorded SWD activity in traps in every month of the year, including the winter. 


For the record, only 8 out of 17 regions were positive by June 1 in 2012, and as of May 30 2013, we are 16 out of 17.  Even if you are in the Union Gap/Zillah region (our one remaining non-positive region), consider yourself on alert for this pest; relatively low trap numbers, rather than low fly numbers, may be responsible.

Thursday, May 30:

Omak and Chelan positive for SWD: Trap samples from Omak and Chelan were found to contain SWD today.

Thursday, May 30:

Rock Island positive for SWD: A trap sample from the Rock Island area was found to contain SWD today.

Tuesday, May 28:

Yakima and Oroville positive for SWD: Trap samples from Yakima and Oroville were found to contain SWD today.

Friday, May 24:

This week has seen a significant increase in the number of trap samples containing SWD. Eleven of the seventeen recording districts are now positive for SWD catches this season.


Friday, May 24:

Othello and Tri-Cities positive for SWD: Trap samples from Othello and Tri-Cities districts were found to contain SWD today.

Thursday, May 23:

Royal City region positive for SWD: Several trap samples from Royal City examined today were found to contain SWD, as did others from Mattawa.

Thursday, May 23:

Brewster and Stemilt Hill positive for SWD: Trap samples from Brewster and Stemilt Hill were found to contain SWD tody.

Wednesday, May 22:

Mattawa region positive for SWD: A trap sample from the Mattawa area was found to contain SWD today.

Friday, May 17:

This week saw an increase in the number of regions where SWD were found in trap samples for the first time this year.

New positive regions were Quincy, Wenatchee, Entiat and Orondo.

Thursday, May 16:

Wenatchee SWD catch: A trap sample from a cherry block in East Wenatchee was found to contain a male SWD today.

Friday, May 3:

The majority of SWD traps are now in place, and weekly monitoring is underway. So far, no SWD have been found from the north of the state.

Friday, April 5:

Trapping has continued throughout the winter of 2012-2013, and likely due to the mild temperatures, SWD have been found in our traps (Prosser/Tri-Cities) every month of the year. No SWD have been caught in traps outside of these areas. However, the early spring we are experiencing will probably mean an early capture in 2013 in all areas.

The eastern Washington volunteer trapping program is on again for the 2013 season, and we anticipate trap deployment in most locations by the end of April. We will be using a new trap style this year, which will hopefully be easier to handle than the Haviland trap. The trap is a 1-qt screw-top jar with 2 large mesh-covered holes. The bait will be apple cider vinegar+surfactant, 150 ml/trap. As in previous years, the samples will be collected and brought in weekly to the TFREC in smaller jars; the trap will remain in the field.

2013 trap history by region

RegionTraps deployedFlies first
Oroville/TonasketYesMay 28th
Okanogan/OmakYesMay 30th
Brewster/PaterosYesMay 23rd
Chelan/MansonYesMay 30th
Orondo-Beebe BridgeYesMay 17th
EntiatYesMay 17th
Wenatchee/E Wenatchee/ Wenatchee River ValleyYesMay 16th
Stemilt Hill/Wenatchee HeightsYesMay 23rd
Rock Island/MalagaYesMay 30th
Quincy/Moses LakeYesMay 17th
Royal CityYesMay 23rd
OthelloYesMay 24th
Mattawa/Desert AireYesMay 22nd
Yakima/TietonYesMay 28th
Union Gap/ZillahYesJune 7th
Sunnyside/ProsserYesFeb 7
Tri-CitiesYesMay 24th
Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us