Beet leaf miner

They don't affect the root but a big infestation on the leaves will slow the plants down. Young plants will be most affected so I don't take any risks with beetroot seedlings now, especially the July sowing.

I'm not sowing anything, I've not got the room. You're more organised than I.  I tend to be like a bull at the gate in spring, sow everything and anything  then run out of room.