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I have a flourishing crop of raspberries (I live on Long Island, NY) but last year and now this year I am seeing tiny little worms or caterpillars inside the raspberries. The insects are white and much, much smaller than the berry. I think the berries infected by these pests become very mushy, not to mention rather gross.

I sprayed the raspberry vines with an insecticidal soap, but it had no affect. I have a more powerful insecticide, but the directions say you cannot harvest fruit for 14 days after application. If I need to go that route I will, because last year these little worms spread to the whole crop and right now they are confined to one area. But since the vines are yielding a bowl of good fruit per day, I would rather not have to waste two weeks worth of fruit.

What could these little worms be? How can I get rid of them? Would food-grade DE be a good option? Should I just use more of insecticidal soap since it is fairly safe?

Related question: I recently discovered a large number of small flying beetles around the vines and on the berries. Could this be the same species as the little white caterpillars?

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    Could be raspberry fruitworm -- could you take some photos of the beetles and the larvae? – Niall C. Jul 15 '13 at 14:27
  • Some of the photos for this fruitworm look like what I'm seeing. I'll add some photos to my question. – Thorn Jul 16 '13 at 18:02
  • I have 3 varieties of grape and one variety is getting attacked by insects heavily while the other 2 are being left totally alone. The one being attacked is growing slower and not producing grapes, while the other 2 are going gangbusters. The insects attacking the raspberries may be doing so because the berry plant isn't that healthy. Maybe fertilizing or changing varieties would help. – Randy Jul 17 '13 at 4:06
  • The plant is healthy, the problem is just with the fruit. I think it's raspberry fruitworm. – Thorn Jul 22 '13 at 19:59
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This is quite late for you but Thorn, you have SWD - spotted winged drosophila in your raspberries. This is a fruit fly new to the US in about 2008. Unlike its cousins, this fly likes just-ripening fruit and lays its eggs there so that the fruit is spoiled by the time it is 'ripe'.

For anyone else coming across this, contact you local Extension agent for help and recommendations to spray. If you use netting, you will have to find some fine stuff and get it on before fruit colors at all.

The little black bugs are sap beetles or 'picnic' beetles that come to ruined fruit. They are not causing the 'worms' you see in the fruit. Unfortunately, since the culprit is a fly, those worms are actually called maggots.

  • Thank you for your accurate response. I am pleased to report that I eliminated the spotted winged drosophila. I was diligent in picking the fruit as it ripened and destroying any that was contaminated. By this time last year and the year before all of the fruit was ruined. But I just picked fresh raspberries this afternoon, so I'm counting this as a win. I did find that Ortho Home Defense kills them, but the company informed me that using this product means you cannot eat the fruit until next season. – Thorn Aug 23 '16 at 17:27
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A light spunbonded poly agricultural fabric, placed over the patch after pollination, might keep some of these insects off of your ripening fruit. It acts as a physical barrier without weighing down the plants. Rain and most of the light pass right on through. I've used it in this manner to keep aphids off my coles and other greens.

  • I might try try that. After applying another insecticide in July the fruit worms came back again. What a pest! – Thorn Nov 5 '13 at 19:44
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Everything I tried last season (when I posted this question) failed to eliminate the fruit worm. I tried a few different insecticides and nothing seemed to bother the worms. I didn't try the fabric because the flying insects are VERY small, the raspberry patch is fairly large, and the berries continue to fruit non-stop for months and bees frequent the berries daily.

A local garden store recommended Captain Jack's Deadbug Brew.

This is an organic product that kills pests when they eat the plant. So far it seems to be working.

  • Captain Jack's Deadbug Brew did not eliminate the fruit fly, but it seemed to slow them down a bit. By August all of the fruit was infected. – Thorn Aug 23 '16 at 17:55

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