What's eating my radishes?

Hi.

I have about a hundred radishes growing. They're in raised beds, under polythene sheets weighed down by bricks so I could control how much water they've had.

I haven't checked them for two days. They're doing much better than my other veg so I left them to it. I went to look at thinning them today and noticed that there's holes in the leaves of about five or six of them.

The raised beds are newly built and they're on casters so I can move them around and I thought not having the planters in contact with the ground might go some way towards curtailing slugs. They use new compost which I bought from the garden center earlier this spring.

The radish variety is sparkler, if that helps. After a quick check online, flea beetle seems possible however I've read up on how the larvae grow and it seems unlikely that they'd be in new compost since they seem to grow over winter and feed on early weeds. I'm not sure though.

The radishes are in a bed next to some lettuce and some french breakfast radish, which are just poking through and seem unaffected. Same with the dill. There's some rainbow chard in the next bed over which is also untouched. 

Anyway here's a (not great quality) photo:

Last edited: 13 April 2017 12:42:57