Only if you move them to a new location after washing them because if newly hatched maggots don't find a food source, they won't survive. Crop rotation is one of the most important aspects of onion maggot control. If newly hatched maggots don't find a food source, they won't survive. If you plant the onions in the same place they came from, the the maggots will attach to the onions. So move them to another spot to stop them completely. Thanks for sharing.