Weeds & Pests

Leafminers in the vegetable garden

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  Leafminer adults are small black and yellow flies. Larvae are yellowish maggots that feed beneath the leaf surface. 
  
  Photos of adults and larvae.

  
  On vegetables, the most common leafminers are the larvae of small flies including the vegetable leafminer, serpentine leafminer, and pea leafminer. Vegetable leafminers may be black except for a prominent yellow triangle between the bases of the wings. The head behind the eyes may be mostly black. The larvae are yellowish maggots that live in tunnels underneath the leaf surface.

  Leafminers may be more active during warm weather, but they are in the garden year-round. They move from plant to plant with each season. The most obvious evidence of leafminers is the twisting trails (or mines) the larvae leave as they feed beneath the leaf surface. Damage will not be serious on most plants older than seedlings, although it may make spinach or chard unsightly.
  
  Leafminers rarely require treatment in gardens. Small seedlings can be protected by row covers. On plants such as cole crops (broccoli, cabbage, brussels sprouts), lettuce, and spinach, clip off and remove older infested leaves. Leafminers are often kept under good control by natural parasites. Insecticides are not very effective for leafminer control.
  
  Read more about vegetable leafminers.