Leek moth has been found in garlic in a community garden in Grafton County. Leek moth (Acrolepiopsis assectella) arrived in Vermont in 2012 and was first reported in New Hampshire in 2016. Since that time, it has been seen in Grafton and Coös Counties. The caterpillar of this moth feeds on Alliums, including garlic, onions, and leeks. There are three generations of this pest, and it is active starting in very early spring (once the soil temperatures hit 50F) in cycles through mid-late August. As you pull your garlic, pay attention for signs of damage. The damage can be confused with that caused by thrips, botrytis blight, and saltmarsh caterpillar – but there are ways to distinguish it and the caterpillar is easy to identify. There are some excellent photos of the damage in these resources:
- Leek Moth Identification Center, University of Vermont Extension
- Leek Moth – A Pest of Onion Crops. Ontario Ministry of Agriculture, Food & Rural Affairs
- Leek Moth, Massachusetts Introduced Pests Outreach Project
These publications also detail management tactics. In addition to chemical approaches, rowcovers and other methods of exclusion can be effective.