Pest (Beetle) Identification Help

[Jackb803]

Hi,

First time gardener here! We're based in Cambridgeshire and over the last week, some beetles have appeared in the garden and started ravaging the leaves of everything in sight. We first spotted four or five of them about 8 days ago, where they demolished our radishes and horseradish. Now they seem to be everywhere. The brussels are looking very sad where they've been eaten and they're flying around and walking all over our sweet corn. They're also all over the mesh tunnel we made for our carrots.

Can anyone help identify these? I've attached some photos. We think they might be flea beetles but they don't jump when you touch them as everything seems to say on the internet. Instead if you touch them, they curl into a ball as if they were pretending to be dead.

What's the best way to tackle these? We want to do something organic, if possible. I've read that, if they are flea beetles, then they'll lie dormant in the soil over winter. Would piling compost on or re-digging the bed over winter bury them and prevent them appearing next year?

Thanks in advance for all your help

[ameno]

I thought they were flea beetles to start with, but upon closer inspection of the picture they looked quite unlike flea beetles. Rather, they are some kind of weevil.

Upon looking it up, I suspect they are cabbage seed weevil. They curl up and drop to the ground when threatened, as you descibe. Adults will eat the leaves of anything in the cabbage family (which includes your radishes, horseradish and brussels sprouts). They then lay their eggs in brassica seed pods, and the larvae eat the seeds inside.
They overwinter as adults in the soil, however these lot you have in your garden now are not the ones who will overwinter. These will be this year's breeding population, looking for somewhere to lay their eggs. It's the ones which then emerge in late summer and early autumn which would overwinter.
Since the larvae only feed on brassica seeds, as long as you don't allow any of your brassicas to go to seed they will be unable to reproduce in your garden, and so you shouldn't have to worry about carrying them from year to year (although there's always the possibility they may come in from outside again, as they did this year). These adult weevils you have at the moment should either die or fly off to find somewhere more suitable to lay their eggs soon.

As they only feed on brassicas, you don't need to worry about them harming your sweetcorn or carrots.

[Plot70]

I would leave the seed pods on until they have laid there eggs and then cut them down and put them on a bonfire.

[Jackb803]

Thanks for all the help. Glad to finally know what they are and it's reassuring to hear they won't go for the sweet corn and carrots.

Hopefully they won't turn up again next year!

[Jungle Jane]

I’d start to squash them depending how big they are,maybe as they’re curling into a ball when you touch them,can you touch them into a bucket of soapy water or pick them up & put them in,I wonder where they came from. Is there another plant from the brassica family nearby they could’ve come from?

[Penellype]

I have a few of those this year too, although nowhere near as many as you do, but a few years ago they completely destroyed a crop of brassica salad leaves, so I do know how destructive they are. I didn't know what they were (I called them cabbage beetle), but cabbage seed weevil seems highly likely.

[Jungle Jane]

I squashed some of those cabbage weevil today,they were on my broccoli plants that I haven’t planted out yet. First time I’ve seen them in real life,they squash quite crunchily not messy really in case any one wondered because I was wondering that

[Snoop Puss]

Mine are covered with harlequin bugs this year. Didn't have any last year. I keep squashing them, but goodness only knows where they're coming from. No eggs on the plants but two minutes after squishing a load and there's another lot.

[Penellype]

I'd never heard of harlequin bugs until your post, but I think I may have seen one the other day - I thought it looked like an odd kind of ladybird. I will keep an eye out now I know what they are!

[Snoop Puss]

They're awful. I've had them in previous years, but last year they seemed to have vanished. They're making up for it this year, that's for sure. I've lost a lot of young brassica plants to them and am thinking that I might have to resort to some kind of pyrethrum chemical treatment to ensure my winter brassicas survive.