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I've noticed a beetle on our fava beans. They crawl out and fly away, leaving perfectly circular little holes. Any idea what they are and what they do? Besides the little hole, the beans seem fine.

I can't post images but they're little dark beetles, maybe 3 millimeters long.

Sue Saddest Farewell TGO GL
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ari gold
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4 Answers4

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The two insects that I know of which would do this are leaf cutter bees and flea beetles. If the bug is in fact a beetle then it’s most likely a member of the leaf beetle family. By the looks of it neither is considered harmful, just a nuisance (though I wouldn’t mind having the leaf cutter bees in my garden for pollination).

Brian Surowiec
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  • Thanks! They're not the leaf cutter bees. Probably a flea beetle - in fact, I found them googling, but nothing in terms of fava beans. Maybe they're members of the leaf beetle family, but they're gestating inside the bean and come out when ready. A nuisance, but neither myself not my customers would like fava with beetles in them. Now I gotta find a way to get them out of the bean. Hmm... – ari gold Aug 21 '12 at 22:32
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I saved beans from the spring crop for future seed in a bag and beetles are now emerging from them. They have the same size and shape as summer bean beetles, but darker color. In past i just save the seed in an open container, and I knew there were larva in the seed from the holes in the beans, but the seed still sprouted so I didn't care.

harlan sanders
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  • Great to know! I was wondering if they'd still sprout. Seems like they would - with such a small hole - but it's good hear that they do. – ari gold Aug 29 '12 at 21:31
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As they've been causing so much havoc, I've been doing more research and found out that they're not bean beetles. They're bean weevils:

http://en.wikipedia.org/wiki/Bean_weevil

That picture of what they did to the beans is exactly what's going on with our favas. Really damaged this year's crop.

Now it's time to research organic controls!

Update: One of the nice things (!) about these weevils is that they don't kill the bean. So while you may not be able to serve 'em in your pub (which is what we wanted to do) you can still plant the bean. Furthermore, unless they die in it, they'll leave the bean so you can still use 'em. Heck, you can still use 'em anyway :-)

ari gold
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Fava-bean-weevil is different than the other beans' wheevils. Scientific names: Broad bean weevil: Bruchus rufimanus Cowpea weevil: Callosobruchus maculatus Bean weevil: Acanthoscelides obtectus

deka
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