[Markjp]

I thought my Garlic were looking very healthy this year, but on closer inspection quite a few of the plants are being attacked by a grub that is eating the top young growth. The leaves are partly eaten and appear stuck together, if I prise the leaves apart there is a small grub around about 1cm long and a whole load of gritty stuff.

Does anybody know what this might be? and how I treat it?

Mark

[Bozwell]

If the grub is white in colour it could be onion fly larvae. Don't know how to treat once you have it though maybe a nematode may be fast acting. You need to be rigorous with your crop rotation and maybe try some companion planting.

[Markjp]

The grub is whitish. 

My garlic are next to my onions. I'm woried now that I might lose both crops.

If it is onion fly how do I treat it?

Mark

[kennykoala]

g,day pull out any suspect plants try to elimanate bugs,goodluck.

[Markjp]

In most repects it does sound like Onion Fly. The difference is that the grubs (maggots) are on the upper new leaves whereas all the articles I can find via Google suggest they tunnel into the roots.

There seems to be little if any treatment. 

Would spraying with Bug Clear have any affect??

Mark

[SG6]

If they are present there seems to be little that can be done. The eggs hatch and eventually bore into the bulb, and can move between bulbs. Thus wrecking eveything.

Now the bad news . They are usually 3 separate occurances in a year. The one now from eggs laid by the flies that hatched from last years laying. Each generation of flies will cause another batch of grubs. 3 in a year.

One site says that alternating rows of onions and carrots helps. Onion flies avoid carrots and carrot fly avoids onions. Fine but it would seem that you already have eggs in the ground.

Recommendations are to dispose of the crop then dig the soil over to expose the grubs to whatever may like to feed on them - birds. Cultivate a friendship with a few robins.

A site whose name I have forgotten suggests nematoads and links to the site below;
http://www.arbico-organics.com/1220301.html

Not sure if bug clear would help, I suspect that the we are into the farming realm of continual spraying prior to any infestation. Sort of spray in case any onion fly occurs. Not even sure it would work, as eggs can be laid on the leaves and in the ground. It may get those on the leaves but not sure about those in the ground.