Onion maggot, Delia antiqua, is a serious pest of onion and related Allium crops (i.e., garlic and leek) in northern temperate regions throughout the world including North America. Although onion maggot will also attack wild relatives of onion, it is not capable of maintaining high populations on wild hosts. Onion maggot completes three generations per year in northern regions. All three generations can be destructive, but the first generation is the most damaging because it can routinely reduce plant stands by over 50% if crops are not protected.