Allium leaf miner

Hi folks, it is confirmed that our onions on the lottie have been hit badly by the allium leaf miner.    
Don't know whether to destroy the whole crop or wait and see, what do you advise.

Thats one of the problems, we try not use chemicals or sprays actually on the plants, or on the plot, so we are going back to planting out in May like last year.

We planted out in mid April this year and that seems to be around the time the flies are emerging and looking for nice tender hosts.  We will also cover with debris netting next year.

Once the area is cleared for the winter it will be disinfected using jeyes fluid and left over winter then rotovated.  I know jeyes is a chemical but at least it won't be on the vegetables and will have all winter to dissipate. (I hope)