LANCASTER - The Allium leafminer (ALM) has been discovered in onion crops on an organic farm in Lancaster County. This is the first discovery of the ALM, an invasive species from Europe and Asia Minor, in the United States.
The ALM can cause 100% crop loss in Allium species (onions, leeks) in heavy infestations. The ALM will also attack ornamental species of Allium.
Look for signs of feeding trails down the stems to the bulb. Pupae can be found during the summer and winter. Will affect multiple layers of the plant and may have multiple larva/pupae per leaf.
The mature fly is 2.5-3.5 mm long with a dark, mat colored body. Head has extensive yellow markings and small red eyes.
For more information or to report possible populations of Allium leafminer visit PA Department of Ag website or contact your local Penn State Extension Office.