The leafminer is a species of pest that is common in field and greenhouse crops resulting in damage to leaves normally referred to as ‘mining’. Mining is the result of feeding activities of the larvae on plant tissue that gives the appearance of tracks on the leaf surface. This damage is very distinct and helps in the identification of the pest. The leafminer is an extremely severe pest of flower crops, sugar beet, potatoes and vegetables.
There are four main species of leafminers in North America, all of which are a shiny black and yellow. However, many different insects are leafminers, including certain flies, wasps, moths and beetles. The immature (larval) stage of these insects produces the distinctive mines that if severe, can compromise the quality and yields of affected crops.
When scouting in field vegetables, sticky traps or sweep nets can be used to monitor adult fly populations; however, the number of adult leafminer flies does not necessarily correlate to leaf damage. Thresholds for leafminers on field vegetables have not been established; however, very high numbers of flies and mines can not be tolerated, as they can cause a severe economic damage to the crops.