I cannot be sure of an ID and control without a description or picture of the beetle. The worst one for the fruit is the raspberry fruit worm beetle.
The adult is a small yellowish brown beetle 4-5 mm long. The larvae are 8 mm long; white with brown areas on the back of each segment. Adults feed on fruit buds and unfolding leaves. This injury can be serious in the spring. After the flowers open, the beetle feeds on the stamens and pistils. Injured blossoms often turn into distorted berries. The larvae enter the young blossoms or fruit and feed on the receptacle. The larvae often remain in the fruit at harvest. Control is difficult because even the organic pesticides are bee toxic and should not be sprayed where there are flowers. Thus they can only be used up to flower bud swell. the adults overwinter in the soil under the plants.
Hi. Thank you SO MUCH for getting back to me quickly. Yes, it is the fruit worm beetle you described. (I examined the beetles and compared online with other images.)
This is the first year I've had them. I think what I might have done wrong is install a composter right next to them, and put leaves all around them for mulch.
Here's what I am doing now, and I would like your opinion of this:
removed leaves around plants so that the soil is exposed
picked and destroyed infected berries (which is the vast majority)
Put infected berries and wrecked leaves in a soap solution in big bucket
Thinned canes and cut leaves closer to the ground
Completely destroyed badly infected canes
I had read online that there are traps. Is that true?
Any further guidance you can give me is most appreciated. We garden organically, and I would never do anything to jeopardize bees.
Thank you! Vicki
After harvest, raking or shallowly cultivating the soil around your raspberry canes can break up pupating larvae in the soil. If you keep chickens, this is a great time to let them in the garden to help destroy the tasty beetles.
http://whatcom.wsu.edu/ag/IPM/raspberry_beetle_fact.pdf is a full discussion of this
problem from a commercial grower point of view, but it does recommend a trap and
how to use it. In April you can start monitoring for the adult beetles who feed on leaves and blossoms and handpick them, dropping them into soapy water. Good luck for next year. What you are doing now is about all that is possible.