If you grow any of the listed Alliums in your garden, inspect them for damage. Look for mined holes and windows in the leaves, small caterpillars, the caterpillars droppings (frass), cocoons, or adult moths.
If you suspect leek moth damage, it is probably best to destroy the plants. It is hard to use pesticides on these insects since they are often found inside the plant. If you do not have damage, a simple row cover can prevent infestation. Infected plants can be harvested and eaten but any portion of the plant not eaten must be burned or bagged and sent to the landfill in order to prevent the spread of this non native insect.
Anne Lenox Barlow has had experience in the agricultural field as a horticulture educator with Cornell Cooperative Extension in Clinton County. She can be reached by e-mail at firstname.lastname@example.org.