Thousands of beetles!

[Lochlibo]

There are thousands of these beetles in my poly
Tunnel. They have eaten all the kale and radishes. Other plants they do not touch like the cucumbers and courgettes. Are they green dock beetles? If so why are they eating my veg and not the tons of dock outside? I would like to get the numbers down without the use of chemicals. Can i change what i am planting? Not kidding about how may there are, i put down my hoe to type this and there are 30 or so noe using it as a bridge!

[mothhawk]

Hi, Lochlibo, welcome to the vine. That certainly looks like a dock beetle. They do eat brassicas, and no doubt a few found their way off the docks and into your polytunnel, couldn't find the way out, and laid eggs on your kale. they overwinter in the soil, so probably best not to put brassicas there next year.

[Zelenina]

It's hard to tell their size from your photo. If they are very small and jump like a flea when you go near the plants they are flea beetles, which are sometimes that colour, and they love brassicas. I had a plague of thousands on my kale and broccoli a few years ago. I discovered that they don't like wetness, so I kept hosing them off with a strong stream of water, which reduced their numbers a lot. And then the weather turned rainy and they all disappeared. I don't know if you can do that in your tunnel.