Integrated Pest Management

More In-Depth Information

Leafminers & Needleminers

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Leafminer damage (Brian Kunkle, University of Delaware, Bugwood.org) 
Leafminer damage

HOSTS

  • Deciduous trees (leafminers)
  • Coniferous trees (needleminers)

DESCRIPTION

Leafminer and needleminers are typically the larval form of many insects that develop and feed of plant tissue underneath the surface of leaves and conifer needles.

BIOLOGY

Overwinter in the soil as pupae with adult flies emerging in the spring and summer. After mating, females use their ovipositor (egg-laying structure) to puncture the leaf surface to feed and lay eggs inside the leaf. Eggs hatch quickly when temperatures are warm, and the developing larvae create visible winding mines as they feed below the leaf surface. Larvae pupate within the mines, on the underside of the leaf, or more typically, in the soil. Adults emerge after about 10 days during the summer months, returning above ground to feed and lay eggs.

SYMPTOMS

  • Larval feeding creates silvery-white blotches or tunneling in the leaf
  • Mining may turn leaves brown and translucent
  • Larval frass is typically present in the galleries
  • Damage is an aesthetic issue, and rarely harms trees

GENERAL MANAGEMENT

To detect and monitor adults, look for new stippling on leaves which indicates the presence of adults. Yellow sticky cards can be placed at plant height (mid to lower portion) and inspected at least twice per week.

INSECTICIDES

The primary target of insecticides is the sap-feeding larva. Since larvae are protected within the leaf, insecticides that penetrate the leaf translaminarr activity) are most effective.

Chemical recommendations (by chemical class) for leafminer control in Utah:

  • Abamectins: abamectin (Agri-Mek)
  • Spinosyns: spinosad [Success, Entrust (organic)] and spinetoram (Radiant).
  • Pyrethroids: gamma-cyhalothrin (Declare), lambda-cyhalothrin (Warrior), permethrin (Ambush, Pounce), pyrethrin Pyganicc (organic)]
  • Neem: adadirachtinn Aza-Direct, Azatin (organic)]
  • Insecticidal soap: M-Pede, Safer’s (organic)
  • Oils: horticultural oil (many brands), plant oils (peppermint, rosemary) (organic)
Precautionary Statement: Utah State University and its employees are not responsible for the use, misuse, or damage caused by application or misapplication of products or information mentioned in this document. All pesticides are labeled with ingredients, instructions, and risks, and not all are registered for edible crops. “Restricted use” pesticides may only be applied by a licensed applicator. The pesticide applicator is legally responsible for proper use. USU makes no endorsement of the products listed in this publication.