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 spotted wing drosophilia (or SWD) 
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Joined: Tue Jan 26, 2010 1:42 pm
Posts: 188
Post spotted wing drosophilia (or SWD)
the numbers seem to have been considerably down during this wet and cool spring as observed by those who are trapping and monitoring them.......but the SWDs are apparently starting to come back now as the weather warms up....

Still and all, last year I could see something squirming in the salmonberries (some of the first berries of the year).....I only assumed these were SWDs without really scientifically identifying them......this year I have not seen anything in the salmonberries and the salmonberries have been quite ripe for a couple weeks now where I live...........and am curious to see what this fickle pest will bring us this year. It is Way, way premature to hope the SWDs are dying down for any fictitious reason.......I fully expect them to come back but am happy they are currently not as fierce as was to be expected.

Other observations welcome. (or has the possibility of new incursions of the stink bug focused people's attentions now as the new kid on the block?)

P.s. Different subject: In order to "log in" I had to click the button "go back to previous page" after I signed in.


Thu Jul 07, 2011 5:15 pm
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Joined: Sun May 15, 2005 10:57 am
Posts: 1354
Location: Portland, OR
Post Re: spotted wing drosophilia (or SWD)
I just harvested my Montmorency pie cherries yesterday. Last year, I noticed some unusual dark spots in them. THis year, I noticed more dark spots than last year, and a few of them were rotten. I am not used to pie cherries being rotten, but this does sound like how they described them in the SWD literature. I brought them in and froze most of them, because even though I love them, I can't eat 300 pie cherries at a time. I save them mostly for the winter when I have very little fruit. Freezing will stop the bugs. I don't mind eating a little extra protein, and except for the 5 rotten ones, the rest still tasted great. I never got around to the traps like I had hoped to, but if next year is drier, it might be a great time to set them up.
John S
PDX OR


Fri Jul 08, 2011 10:08 am
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Joined: Wed Nov 17, 2010 9:43 pm
Posts: 34
Location: SE PDX
Post Re: spotted wing drosophilia (or SWD)
I was thinking about asking this question as well but DonRicks beat me to it! As a quick reminder, last spring I encountered SWD maggots and damage in my raspberries. I cut down the summer-bearing canes while I figured out what to do. I made drawstring bags from no-see-um netting which I used to protect berries on the fall-bearing canes. I also stopped composting since that attracted Drosophila. During the winter, I re-started the compost pile and early in Spring, I noticed Drosophila so I buried the recent compost under a couple of inches of shavings/horse manure. (I have ready access at a stable.) This seemed to drive them away which was encouraging. As the raspberries started to set fruit, I bagged them using the bags I had made last year. However, it became evident that I was going to run out of bags so I have had to make more. (As an aside, I am trying Agribon 19 rowcover material which is cheaper for my newest batch of bags.) I am still behind the berry-ripening timeline but I have been able to pick ripe/undamaged berries from inside and outside the bags. I have also been looking for the flies around the berries and so far (knock on wood!) I have not seen any. It is still early though so I'm still going to try and keep bagging as many as I can. I suspect that the wet/cool spring delayed the ripening of the hosts for the breeding areas so that kept the numbers down. I also suspect that not putting items in the compost pile helps as well.

As for the brown marmorated stink bug, I caught one earlier this year but the numbers are down from previous years. I have never been able to detect much damage from them unlike the reports I have seen on other forums from back East. It sounds like bagging fruit does not prevent damage so hopefully we won't have much trouble here!

I would be interested in hearing other reports especially from LeeN who had trouble last year with SWD.


Fri Jul 08, 2011 7:55 pm
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Joined: Tue Jan 26, 2010 1:42 pm
Posts: 188
Post Re: spotted wing drosophilia (or SWD)
Here is what Dick Tilbury wrote on July 15th, 2011 for the Western Cascade Fruit Society newsletter here in Washington state:


Re: spotted wing drosophila (SWD)

We’ve been trapping Drosophila one to three times a week since March 15, 2010 at our south Seattle site. SWD and D. subobscura have been the principal species trapped. D. simulans, D. busckii and several other species have been trapped occasionally in smaller numbers. From September 2010 thru January 2011, the overwintering generation of SWD was trapped in huge numbers and was at least 95% of all Drosophila caught each month.

Research in the early to mid 1950s in AZ and CA established that Drosophila live on wild yeasts on trees and other plants. SWD do not need fruit to survive--fruit are reproduction sites, not feeding stations. (We are unaware of such research for our maritime climate. If you can cite a paper on this subject, please do share it with the forum.)

This spring was brutal for many insect species and insect eating birds. Our Drosophila trap numbers began declining in February and now are roughly 20% of the numbers last year at this time. In 2010 every Montmorency cherry was infested with SWD. This year only 15% of the fruit was infested, and those cherries were hit 3 to 5 times each instead of up to 15 times.

Still, SWD has the ability to complete its life cycle in about a week under favorable conditions. Cherries, plums, peaches, cane fruit, blueberries, thin skinned grapes and cherry tomatoes are vulnerable if the population should explode. When such fruit begins to ripen we suggest hanging a trap or two around it to see if a SWD population exists (look for spotted wings of the male). If present, hang more traps, harvest promptly and often, and remove all spoiled fruit immediately.

The most effective bait for us is 1 packet yeast, 4 teaspoons sugar, 1.5 cups water. Insects can be sieved out weekly and the bait topped off with more sugar water to keep it going thru the summer.


Sat Jul 16, 2011 11:59 am
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Joined: Sun May 15, 2005 10:57 am
Posts: 1354
Location: Portland, OR
Post Re: spotted wing drosophilia (or SWD)
Excellent post, Don.

I thought I was going to set up traps for this year but it got away from me. I figure I'll set it up for next year.
John S
PDX OR


Sat Jul 16, 2011 4:02 pm
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Joined: Wed Nov 17, 2010 9:43 pm
Posts: 34
Location: SE PDX
Post Re: spotted wing drosophilia (or SWD)
Thanks Don for the information from Seattle.

A quick update since my last post - I have found evidence of SWD in 3 of my raspberries so far and I killed 2 Drosophila that were flying around the bushes so they are still around here lurking......


Mon Jul 18, 2011 8:01 am
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Joined: Tue Jan 26, 2010 1:42 pm
Posts: 188
Post Re: spotted wing drosophilia (or SWD)
Okay, I have some August 20, 2011 updates:
1. Personally, I spotted larvae in my backyard Himalayan blackberries.....probably SWD.....and others have spotted this pest now in other fruit as well......
2. However, the numbers of SWD have been way lower this year than last year. This does NOT mean they have gone away. We can hope the spotted wing drosophilia has been contained by some sort of an infection or something, but we have no evidence of that....they will be around as August of this year progresses and will probably be here next year in good numbers....so we can not celebrate any funeral services yet, by any means.

I attended the Mt. Vernon Research summer tour today and I personally talked for some time with Dr. Beverly Gerdeman who has been actively researching this pest. A couple notes:

3. There may be some promise in the exploration of using insecticide treated netting. One can totally contain the problem with a mesh netting size smaller than .98 mm however such a small mesh netting invites fungal problems to the plant and fruit at precisely the wrong time. Of more promise is a larger size mesh netting or shield that has been sprayed with an insecticide. Why? Because the SWD fly is clumsy and it never flies straight through the net but will die on contacting the net. And for allowing wind and sun, etc. in then it would be nice to get away with a larger size netting. The fly has to land on the netting before it prepares to enter into the zone where the bush/tree is. The problem is: we don't know if the 4 hour interval time between contact and death is sufficient because if the fly puts the egg inside the fruit after it has landed on the insecticide net but before it dies then we don't have an answer at that point.

4. Pyganic and Entrust are both effective insecticides. Apparently both are organic. I think Entrust is a Spinosad fermenting bacteria and has the longer post harvest interval (3 days).

5. A good way to see if you have the larvae in your fruit is to put the berries in a pan and then cover the pan with a 1 tablespoon salt to 1 cup water solution. This will drive the larvae out to where you can see them.

6. Only 5 % of the berries or less have eggs implanted in them if they have not reached the stage of being near full (?) color. So netting or insecticides do not need to be applied for the full growing season.....essentially, a good idea is to think about it when the berries start coloring (the last sentence is my surmisal alone and my words/thoughts).

7. Good news: we haven't seen many of the plums affected by SWD. Bad news: we have seen some Asian plums affected in some parts.

8. NEEM oil doesn't work well for this insect.

9. Trapping will work......if you are Chinese and can afford to pay your workers $1 an hour to be constantly changing your traps throughout the orchard (I joke only a little here).....otherwise, trapping only reduces the problem and is not commercially viable. Put your apple cider vinegar traps under a canopy as the flies prefer a slightly shady spot.

There are answers out there...but we are still learning about this pest and it has many complicated patterns......and prediction models do not have all the data to know what the behavior of this pest will be with probable certainty at this point for some of these behaviors......the reproductive/ food needs of the female, for example, may vary at different times and temperatures.....Western washington's mild summer has probably slowed things down this year. I assume the same is true of Oregon but suspect Oregon has been a little warmer and had a few more SWDs.....again, my own thoughts/ conjectures on that.

So, we have some more data, some new facts.....and some guess-work.

http://www.mountvernon.wsu.edu/ENTOMOLO ... s/SWD.html


Sat Aug 20, 2011 4:05 pm
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Joined: Sun May 15, 2005 10:57 am
Posts: 1354
Location: Portland, OR
Post Re: spotted wing drosophilia (or SWD)
Thanks Don,
Excellent information. Thanks for talking to the experts at Mt. Vernon.
John S
PDX OR


Sat Aug 20, 2011 9:04 pm
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Joined: Wed Nov 17, 2010 9:43 pm
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Location: SE PDX
Post Re: spotted wing drosophilia (or SWD)
I was thinking that I should post my latest observations regarding SWD when I saw Don Ricks had posted some interesting updated material. So far, I have harvested the summer-bearing canes for my everbearing raspberries with far more good berries than damaged ones. I covered as many berries as I could with my homemade bags made from no-see-um netting or Agrigon row cover which I hoped would minimize the egg-laying. I removed the summer-bearing canes and now I have the fall-bearing canes with berries. I went away for a week just as one set was starting to turn color so I removed the netting from the ones closest to harvesting since my caretaker was more likely to pick berries if they were uncovered. Upon my return, I re-installed the bags though, again, not all berries are covered. Actually, I should install more bags soon since there are more green berries present. I pick berries every day and I have found some "bad ones" which I freeze before disposal and I saw at least 1 Drosophila sitting on a berry but, overall, it has been manageable. Last year I would see a number of flies swarming around the berries. I think the cooler spring slowed down SWD reproduction since the cooler weather also slowed the production of berries. However, I also changed my composting habits so that I bury my current waste into the compost pile to minimize the attraction of the compost pile. It is a bit unfortunate that netting raspberries is labor-intensive but I think I'll keep pursuing it since it seems to help.

As for blueberries, I covered the berries as soon as the fruit set. I have harvested berries from the Duke variety but I'm still waiting for the Bluecrop to go through the final ripening stage. I don't know if having them covered is slowing the process down since that may shade them more but I don't want to uncover them to find out. Hopefully, our recent warmer weather will help out.

It would be nice to hear from someone like LeeN who had a lot of trouble with them last year to hear if damage was less this year.


Sun Aug 21, 2011 8:37 am
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Joined: Sun May 15, 2005 10:57 am
Posts: 1354
Location: Portland, OR
Post Re: spotted wing drosophilia (or SWD)
I had dark spots in my pie cherries. I ate and harvested them and they were fine. I froze most, so if they had SWD, they're dead now. Only one or two was rotten. I have noticed no problems on blueberries, blackberries, or anything else.
John S
PDX OR


Sun Aug 21, 2011 10:40 am
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Joined: Sun Jan 11, 2009 12:01 am
Posts: 36
Location: S.E. Portland, Oregon
Post Re: spotted wing drosophilia (or SWD)
We've got problems in our marionberries and blueberries.


Sun Aug 21, 2011 8:10 pm
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Joined: Tue Jan 26, 2010 1:42 pm
Posts: 188
Post Re: spotted wing drosophilia (or SWD)
A disclaimer for this and all other posts I make: I am not authorized to speak for Mt. Vernon Research or any other agency....and I am bound to get some details wrong....(especially if I insist in writing in a "folksy" manner)......and any "official" recommendations from anyone in a governmental capacity would of course tell people to follow proper label directions.

Having said that, I have a few corrections to my previous post:

1. Commercially available impregnated cloth is not intended for use on a food crop. (If I, Don, personally decide to try some experiments on my own.....well, hmmm.......another time and place to talk about that, maybe)

2. What Mt. Vernon Research will be testing is the efficacy of chemically treated shade cloth draped over a trellis wire on blueberry in the coming weeks. This is 40% shade cloth and the cloth does not touch the plants. They will observe for fungal diseases and post the results on the website when the results become available. This is my understanding, anyhow.

3. The dearth of flies has made some summer research of the SWD problematic until now but there seem to be a few more flies now....maybe only a few.


Tue Aug 23, 2011 6:15 pm
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