Is this onion fly damage?

A few of my leeks have been really nibbled by, I think, onion fly. This one, for example, has lost its main growing shoot and is looking pretty unhappy.



A couple of questions, please:

Am I right to think it's onion fly?

If I use fleece to deter the little blighters next year, how long do I have to keep it in place?

This happened a few years ago to me and the nibbled leeks did recover quite well late in the season so I'll give my injured specimens a big nitrogen boost. Just wish it wasn't necessary.

 

John

Thanks for your views. My photo doesn't show it but the nibbling extends down into the core of the plant so I don't think it was done by birds. They tend to shred everything visible; at least, the pigeons round here do!

Slugs are certainly a possibility and come to think of it, I've had problems with large numbers of tiny slugs in my raised beds. They're hard to see unless you actually catch them on your veg and they don't seem to take the pellets. I'll just have to be more vigilant.