Pest Alert – Allium Leafminer

Joanne Whalen, Extension IPM Specialist;

The allium leafminer (also known as the onion leafminer) has recently been detected and confirmed from infested leeks and onions in Lancaster County, PA. This is the first confirmed infestation in the Western Hemisphere. HOWEVER, this insect has not been detected in Delaware. If you think you may have observed damage or a life stage of the allium leafminer, it is important that you contact Steve Hauss at the Delaware Department of Agriculture by email ( or call (302) 698-4500 for official confirmation since this would be a new detection in Delaware.

The following pest alert written by written by Shelby Fleischer, Department of Entomology, Pennsylvania State University, University Park, PA, and Tim Elkner, Cooperative Extension, Lancaster County, PA and edited by Dan Gilrein, Cornell Cooperative Extension of Suffolk County provides information on damage symptoms, insect identification and life history, monitoring and potential management options