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Home » Organic Gardening

How To Prevent Raspberry Worms & The Spotted Wing Drosophila

Submitted by on September 11, 2013 – 8:02 pm 37 Comments
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It seemed as if nothing could stop my prolific raspberry bushes from running their marathon harvest. And then the worms came.

I started noticing them a little here and there. No big deal, right? I’d just soak the raspberries in salty water {how-to here} and dump off the dead floaters. But then what began as a small nuisance suddenly became an unmanageable infestation.

Where were these worms coming from?!

Spotted Wing Drosophila

My guess was that they had something to do with all of the tiny little gnats I’d noticed swarming around my bushes. See that fly on my raspberry there? Look closely, I’m working with a point and shoot camera here. Turns out, I was right. Those teeny, almost translucently white worms are the larvae of fruit flies. The Spotted Wing Drosophila is one type of fruit fly which is becoming a particular problem.

The difference between the SWD and regular fruit flies, besides the tell-tale black spot on the male fly’s wings, is that while everyday fruit flies generally lay eggs in overripe or damaged fruit, Spotted Wing Drosophila have a more aggressive approach. They lay their eggs in the flesh of underripe fruit, making it hard to beat the bugs to the harvest. The eggs hatch, and those nasty little worms are soon to follow.

These pests are actually relatively new here, and are becoming a HUGE pain to berry growers across the US. Not only do they effect raspberries, but blackberries, blueberries, cherries and strawberries as well.

Experts are still testing different methods of control, but there are a few preventative measures you can take to reduce the chances of an infestation:

  • Keep plants picked of ripe fruit. Ripening fruit will attract the Spotted Wing Drosophila, and will spread breeding grounds. Do not leave overripe berries on the vine, and do not let them fall to the ground as this will encourage an infestation. Pick the vines clean, and do not compost unwanted berries. The heat from the compost is not high enough to kill the SWD larvae and they will reemerge the following year. I’ve been feeding my overripe berries to the chickens, but you can also seal them in a ziploc bag and leave it out in the sun to kill the worms. You must keep your plants picked clean of all ripe fruit every single day.
  • Keep plants pruned. Fruit flies like humid, shady environments. Thin ’em out and keep sprawling varieties trellised. Burn the prunings instead of composting them.
  • Do a ground clean up. SWD larvae can overwinter in the soil and reemerge the following year. It is recommended that you cultivate the soil around your plants to expose the larvae to the elements. They don’t survive well in very cold or hot temperatures. I’m going to go an extra step and sprinkle Diatomaceous Earth around my plants after I thin them out.
  • Set traps. You can put out a vinegar or yeast-sugar trap to lure these pesky flies. It won’t catch enough of them to help a bad infestation, but if you set the traps out when the fruits are just beginning to appear, you will be able to monitor the arrival of the flies. Setting traps at the end of the season might also help reduce the population for the following year. Page 2 of this document explains how to make your own fruit fly traps.
  • Cover your plants. You may be able to prevent the flies from landing by covering your plants with a very fine row cover before the fruit even begins to appear on your plants. Be sure to close it off so that flies cannot get underneath it. This method, however, can sometimes pose problems with air circulation.
  • Harvest in Spring not Fall. Fruit flies tend to be more of a problem with Fall crops, particularly beginning in July. If you have an Everbearing variety, you might want to prune them after the Spring harvest so that you don’t get a Fall harvest that would attract the SWD.
  • Spraying. There are two organic insecticides which have been found to be helpful in reducing SWD population: Entrust and Pyganic.

I can’t tell you how frustrating it is to pick quarts and quarts of gorgeous red berries just to open them up and find worms crawling all over them. I’ve continued soaking them in the salt water solution and rinsing, rinsing, rinsing, until all of the worms are gone- then freezing them. This is just one of those mind over matter deals. I’ve resolved that if I end up eating a couple of worms, as long as I didn’t see them first, I’m good with that. Next year, I hope to be ahead of the game.

What about you, have you had trouble with worms in your berries this year?? What are you doing to treat the problem?

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37 Comments »

  • Matt says:

    When I picked I look inside, if I don’t see anything right away, in the bucket it goes, I don’t wash the berries, raspberries tend to fall apart if you wash them, I just freeze em on a cookie sheet. I find quite a few of the worms on the sheet and I try to not dump them in the bag. Mind games I play with myself I guess. Next year I’ll let the chickens out while I’m picking again. Did not have the worms as much when the chickens were out more. I have had problems with coyotes so they aren’t out as much. I’ve just been dropping the discards on the ground for the dog but there are a lot of berries on the ground. I will change how I do things next year. Thanks for the article.

  • Susan Huetter says:

    Hi,
    So excited about your website..had beautiful berries and then..one day I have beetles worms oh NO!
    Some people who have shared the solution to bugs..but does anyone have a organic natural spray..idea or recipe..homemade to GET rid of the pests??
    Anyway Happy Gardening from the Central Coast California…
    Susan

    • Nancy Nowak says:

      I have used Monterey Garden Insect Spray. It contains Spinosad which is considered organic. It has worked well for me on my raspberries and blackberries. I sprayed about once a week when raspberries were ripening. I sprayed at night so that bees wouldn’t be harmed. I used a tank sprayer. My black raspberries which ripen first were not damaged. But the red raspberries are always a challenge. I pick with a little plastic bag to thrown in any berries that seem quite soft, There aren’t too many of those.

  • Brooke says:

    I thought I was loosing my mind when I saw the little worms in my raspberries. Thank you for helping me feel sane again.
    I do have some questions. How important is it to create rows of plants? My raspberries grow in a 12 x 20 patch in the corner of my yard. To make the area into rows will be very difficult to do.
    Is it possible to eradicate the worms or will I need to battle them every year? or should I rip the raspberries out and quit now? Is there an effective spray pesticide? I also have rhubarb growing on the side of my patch, will it get infected? The biggest question: I have always given my raspberries to friends and co-workers many have frozen the berries for use in smoothies during our long winters, do I need to tell them not to use the berries? Any answers would be greatly appreciated.
    Brooke in Minneapolis, Minnesota

    • Kendra says:

      Raspberry bushes need to be thinned out to prevent disease and pest issues from becoming too prevalent. The more crowded the plants are, the harder the fruit will be to harvest and the more will rot, therefore drawing the drosophila fly to lay eggs on your fruits. If you can thin them out so that you can get in between them it will help. I’ve found that if I harvest the raspberries that ripen in spring they’re fine, but once we get into summertime the berries tend to get worms. I wouldn’t pull the plants up, but just keep an eye on when you start seeing worms and stop harvesting then. I’ve never sprayed my plants, but definitely go with something organic if you decide to try a pesticide- you don’t want to poison yourself. The worms won’t hurt you if you eat them. πŸ˜‰

    • Mrs. Hansen says:

      Hi Brooke,
      I feel your pain! We had this exact problem and lost our entire crop of “Caroline” raspberries last year! I just can’t seem to look the other way when it comes to worms. So I called the Utah County Extension agent, who told me the “Dusky Sap” beetle was the villain! It’s a tiny 1/4″ long beetle that comes out in the spring and lays it’s eggs near the blossom and when the fruit forms, the egg hatches and then you have the worms. My backyard neighbor freeze dried theirs (same variety) and said the worms fall out if you do that. I wasn’t convinced… This year we sprayed very early with Malathion, to eliminate the beetle, who comes out in early spring (March) to lay it’s eggs. Guess what! No worms, spider mites, or anything! Much happier!
      Good luck whatever you do! I wasn’t happy using any kind of spray once the raspberries are on–didn’t want the chemicals then, but early spring when they were starting to blossom was fine with me! The County Extension agent said, it helps to pick the raspberries when they are ripe, and not let them get overripe, but that didn’t stop the problem for us. Good luck whatever you decide to do!

  • Helen Mccurry says:

    Hi, We have never been bothered with these little worms here in North Carolina. I was dumfounded when I picked a gallon of raspberries and proceeded to run them through cheesecloth to make jelly. I was disgusted to see little bitty worms crawling all over the jelly bag. I threw the whole thing out yuk! There has to be something to spray on the bushes to kill these little buggers. Thanks

  • Kathy says:

    We too in Iowa have been invaded by these little buggers. The past two years we have picked the red raspberries and promptly fed them to the chickens because of finding so many worms. And of course the past two years we have had bumper crops! Is there anything new since 2014 that has been found to eradicate these from the berry patches. I did buy captain jacks dead bug brew and sprayed at the beginning of harvest last year but was too late to stop the bugs. Will try spraying much earlier this year but would like to know if anyone else has found something better to eradicate this pest.

  • Blueberry says:

    That SWD will spell the end of Organic. The pyganic, due to over use by aerial applications by large corporate organic producers, is ineffective due to resistant build up and the Entrust is limited to five applications per season–and has a 3 day waiting interval after application until you can harvest the fruit…This means there are no organic options left since the fly lays eggs in the green fruit. The good news is many conventional insecticides have a milder 1 day until harvest interval and that is really all that matters. Yes, entrust is worse, despite being organic, than say malathion. The PHI is all that matters as both are made in laboratories.

    What the outcome will be is producers will have three choices.
    a. grind up the worms and the crop and call it organic plus protein.

    b. freeze the crop with the worm in it and call it organic instead of neglected

    c. use non organic but milder than organic insecticides and properly maintain their crops management.

    I choose c. Who needs extra protein.

    Take care,

    Blueberry

  • Dorothy says:

    I picked 2 qts. of red raspberries yesterday, refrigerated them and when I opened the container this morning I noticed for the first time tiny white worms. We cut our bushes down to the ground each year so that we have a large late summer crop. Currently, I have 4 gallons frozen from this year plus I’ve made 14 jars of jam. Is it possible that there are worms in these two items?

    We are devastated to have this issue and are happy to find your informative site.
    Dorothy

  • Robbie says:

    I noticed the tiny little worms inside my raspberries last summer. This summer I made sure I picked my berries right before they got too ripe and seemed fine. But I am wondering if there are eggs, and they hatch once the berries get more ripe. I’m not sure how many I have eaten, but I am just sick about my raspberries. We have been picking them and putting them in an airtight bag to throw them away.

    I am thinking of cutting my stocks down to the ground, raking the earth, and putting some sort of worm killer in the ground and hoping this will get rid of them this year and help reduce the numbers for next year. What do you think about that?

    Next year I will put out containers that will attract the flies away from the berries and hope for the best. Someone also suggested I put three inches of cedar chips in my patch. What do you think? Would appreciate your thoughts.

    • Kendra says:

      Hi Robbie,

      We were very diligent about picking our raspberries this year. We picked the good ones and the bad ones, so they weren’t left to rot and attract the flies. I didn’t find any worms in our berries this year. If you want to sprinkle something on the ground around your plants, I’d recommend Diatomaceous Earth. It’s natural, and won’t harm the beneficial insects or the earthworms you don’t wanna kill.

  • Janet says:

    UPDATE: Found your AWESOME article again while looking for more info re the SWD Beasties as I Truly CRIED last year after throwing buckets of raspberries away. I TRIED what I could to get rid of the li’l nasties, to NO avail.
    Found this article this morn from California, sharing as it had some additional about them. Have you seen this one?http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74158.html
    I just KNEW the BITTER COLD WINTER we had would SURELY have killed all these danged things off, but NOOOOOO… Mother Gaia decided to test my resolve in 2015, too – Grrrr…. πŸ˜‰
    Sadly I’ve already found the buggers in my Strawberries… Keeping fingers crossed, eyes peeled & traps at the ready for my raspberries & chokecherry tree. πŸ™‚
    If you have learned any more info would LOVE to hear it! πŸ™‚
    Best Wishes, and Thx again for this article and your web site – it ROCKS! πŸ˜‰
    Janet
    Ft Collins, CO

  • Hosea says:

    The white spots are from a lack of sunlight, not harmful.
    Hosea

  • Debbie says:

    I just googled worm in red raspberries.So glad I found your site ! We live in Ohio and have been growing red raspberries to make all kind of goodies with, including wine ! We have probably been growing them for 8-10 years and this is the first year we have ever found worms. I soak and rinse and soak and rinse also.And then freeze. We are having another problem with the berries also and I was wondering if you can help with this. Some of the berries have white pieces of flesh, like the little balls that make up the berry. Some are grouped together and white with no red pigment. What could that be ? Any help will be appreciated ! Thanks !

    • Hi Debbie,

      I’m glad you found your way to to my site. I’m sorry I can’t help with the berry problem. I’m not sure what would cause some pieces to be white. Maybe a fungus? Definitely worth researching.

    • Tami says:

      I’ve been growing berries for 12 years. When this first happened two years ago it always went with higher heat spells. We tossed hundreds of pints….I also noticed the white drupelets. Sometimes berries were fully ripe with little color. I don’t think they are ripe though, I think the eggs just soften the berry as they are growing into worms which breaks down the tight barrier between the drupelets that keeps them firm. I cried too as I threw away hundreds of dollars of income every time it got hot. I’m going to do more research on the incubation period etc. to get this under control. I’d love to be organic but I am finding that in the northern states more insects seem to be coming up further and further from the south with overall warming. Thrips use to be a rare occurrence in strawberries in Wisconsin, and now they seem to be occurring often. I think the road ahead for fruit growers is a very very tough one. Overuse of insecticides are creating superbugs. I don’t use insecticides unless warranted, but will not hesitate if my entire income depends on it. I lost an entire strawberry crop in 2006 due to thrips and lost tens of thousands of dollars. Sadly by the time we lost the crop, most of our inventory for sales, like boxes etc. were already purchased. It’s been a rough profession. If I find more info, I will share here too. Thanks and so glad I found this site.

      • Kendra says:

        I hate to hear of all the trouble you’ve had, Tami! I’m sure that can be extremely discouraging and heartbreaking. I’ve been trying to learn more about permaculture and food forests as a solution for keeping pests and disease under control naturally. It’s pretty interesting stuff, if you get some time to look into it.

    • Sheryl says:

      The white spots are from some type of beetle, I think they are a type of stink bug but not sure. They suck the juice out of each individual ball(?) on the berry. I battle them each year. They are hard to spot and smart. They are usually greenish in color and a little smaller than a dime or less. They are quick and hide under the leaves or start crawling down the stems. You just have to pick them off and squash them. Sorry I haven’t found another solution yet.

  • Barb says:

    My raspberries were great and larva free until I believe it was 2012 we had a very cold spring and all blossoms on fruit trees froze in our area, that was the summer our raspberries became their target here in South-western Ontario, Canada. Great to find some suggestions to help with the problem. It’s a real pain trying to beat these pests to the fruit, as soon as you pick an infested berry you know by the softness of the top of the berry. Turn it over, look in inside and you see the juice, you know the worms are there before even tearing it open.

  • Rachel says:

    Iowa girl here, with backyard raspberries that we inherited when we bought the house ten years ago. This is the first year we noticed the larvae, but my eyesight isn’t the greatest and my visiting daughter found them. Who knows how many we unknowingly ate already! I think the bushes are hopeless for this picking. We will try to trim them up, put out some traps, and hope for the best in the future. Thanks for the great suggestions!

  • Subie says:

    Thanks for putting a name to my nightmare, and suggesting so many possible solutions!

    Disgusting thought: how many of these have I unknowingly ingested? I always nosh my way through a picking and I never noticed worms before this year, but just dumped out today’s entire harvest after about half a dozen rinses, then cutting open several of the remaining berries and finding one or two tiny inhabitants nestled inside each one, damn!

    I’m no farmer; these are just wild canes/brambles in my backyard, about 12 feet high and maybe 15-20 feet in diameter, plus smaller satellite vines around the yards perimeter; no way to remove ripened fruit at all in some places, much less daily…

    Do you think I should cut the main bramble down at the end of the summer and try to forgo a crop next year? I live in Northern CA, about 2 blocks from the Carquinez Strait, and it’s alternately nicely hot or cool with fog so my conditions are perfect for the little buggers…

    Thanks again,
    Subie

  • Janet says:

    OMG, how I LOVE the Internet! Googled “tiny white worms in raspberries” & Wha-la! MY SAVIOR appears! πŸ˜‰ Live in Ft Collins, CO & just SICK about the Massive poundage I had to throw away in 2013… ARGH!!! I even opened baggies in freezer from earlier harvests like July 4th, & to my dismay EVERY BERRY I OPENED had visible critters. Same symptoms. Actually first noticed hard spots on outside of berries, both new & overripe.. Then started noticing all the “gnats” (aka ‘UFI’s’ @our house since many flying species are simply unknown to us!) Also noticed we had Loads of earwigs in the grove as well, a first… wonder if related? Anyways, I WC Colorado Extension & see if they have eradication suggestions as we’ll. πŸ™‚ TX foe writing this, soooooooo glad I found answer to my burning question! ~ Jo

  • Diana says:

    HI,
    I love that I found your site…so much to read. We took the “leap” September 2012. We had been looking for an off the grid home where we could not only live, but thrive. We now are building up this 20 acre previously Amish owned farm to be our dream home. We plan to stay off grid and plan to grow much of our own food. We do all the work ourselves, building every thing we need ei: 40ft green house for our year round growing needs.

    I look forward to reading more on your site.
    Diana

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