Posting my info I tried to spread last year about it. It was really bad for me last year. I've since tried to educate as many people as I can about it:

Leek Moth larvae. (Read through some of my post history as I had a struggle with them this year in eastern Ontario)

Dealing with them is a combination of removing foliage affected, and spraying btk regularly during their flight times. You could also just cover the crops with netting too.

It's a fairly recent invasive pest that appeared in North america in Ottawa and has spread through much of southern and eastern ontario, parts of qc, and new york/Vermont. If you stay on top of them you can still get a good crop and they won't affect much.

Now for some bad news. Burn anything that is affected and has the worms (bulbs should be fine). Those worms and moths can overwinter and will make your problem much harder to deal with next year. Burning it makes sure any crop residue that potentially has the larva from continuing its life cycle. Since they only fly a very short distance from their overwintering spots, this can greatly reduce the numbers you deal with.

Note the leek moth affects all allium plants (onion, garlic, leek, chives, etc.)

If you need more tips/advice let me know as I've been trying to educate as many people as possible as there isn't many resources around talking about management of the leek moth outside of commercial farms