Holly leaf miner, Phytomyza ilicicola, damages a number of holly varieties by feeding between the upper and lower surface of the leaf tissue. These mines ruin the aesthetics, may cause partial defoliation, and can lead to early leaf drop in heavy infestations. Damage is also created when the female leaf miner adults pierce the leaf tissue to deposit their eggs. Feeding of the sap occurs at these wounds and causes leaf deformities.
Holly leaf miner is usually an aesthetic problem unless there are large numbers of mines. When possible, American hollies should be grown in partial shade. Trees in full sun are usually more heavily damaged by this pest
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Holly Leafminer Treatment Option 1
Soil application of Optrol ™ is effective in controlling leaf miner larvae. An annual treatment will keep this pest as well as other sucking insects from injuring the tree. Optrol ™ can be applied anytime the ground is not frozen or saturated, however the best control will be seen when Optrol ™ is applied as adults are emerging in the spring through April. It can take as long as 30 days for imidacloprid (Optrol’s active ingredient) to move into the leaves, so as eggs are hatching, feeding larvae will be controlled with late April Optrol ™ applications. Fall applications can also provide great control for the following season.
Application Type – Soil drench
DIY Product/Equipment Needed:
• Optrol ™
• Measuring or diameter tape
• Soil drench: Bucket, watering can, or Soil drench kit (includes a quart of Optrol)
How Is It Spread?
• Pupation occurs in early spring (March/April)
• Holly leafminer adult flies emerge over a six-week period beginning in May.
• After mating occurs, the female pierces the underside of the young leaves (which causes tiny green blisters) and deposits her eggs.
• Eggs hatch in about 4 days, and the larvae begin to feed on the leaf tissue between the upper and lower leaf surface, creating new mines.
• Over wintering occurs in the leaf mines.
Holly leaf miner is a pest that affects many varieties of holly including American holly, English, dune holly, inkberry, deciduous holly, Japanese winterberry, winterberry, and yaupon holly.
• Initial symptoms of holly leaf miner appear as short (1/2 inch), slender mines in the leaves.
• The leaf mines become wider, and eventually may cover the entire leaf with yellow serpentine mines, and/or brown blotches.
Spring or Fall
Risk of Spreading