Borers

Natural Control of Borer Pests – Moth, Beetle & Wasp Larvae

Borer Control with Organic Solutions

Insects called borers can be found worldwide across several unrelated groups of insects and reflects their boring larval stage that affects buds, shoots, bark, trunks of trees, shrubs and other plants. Many will develop into beetles (Coleoptera), moths (Lepidoptera), or wasps (Hymenoptera). Some borers are incredibly target specific. The larval stage damages plants by destroying internal plant tissue as they feed and mature, which can be noticed by dark or discolored areas with sap and sawdust-like residue clinging to the bark or littering the ground around trees in the case of tree borers, or by visible trails marking the leaves in the case of leafminers.

This page focuses on general borer control. Please scroll down to the bottom of this section for more information about specific borer pests like European Corn Borer, Iris Borer and Squash Vine Borer.

Life Cycle:

Timing of life stages throughout the year will differ depending on the species of borer, your location and environmental conditions, but all borers go through complete metamorphosis with four life stages: egg, larva, pupa and adult.

  • Eggs – Laid when adults are mating on or near the host plant. Common egg-laying sites are on or under bark, in leaf litter/detritus on the ground, and in cracks of tree trucks or branches.
  • Larvae – Once hatched they bore into the host plant using digestive enzymes and begin feeding. Feeding will increase progressively as they grow.
  • Pupae – Some borers pupate in or on the host plant; others drop to the soil and pupate there. No damage is done during this stage.
  • Adults – Emerging from the pupae, adults mate and seek out optimal sites for eggs to be laid.

Damage:

Borers' main economic impact is incurred when the wood or crop is harvested. In the case of timber, they create tunnel tracks that reduce the value of the wood and make it unsuitable for veneer. Some species of borers leave wood unusable because their damage weakens the wood fiber and degrade the wood quality. Agricultural crop damage ranges from stems with bored out contents, to enlarged stems/branches with galls, to damaged buds and fruit.

Pest Borer Control

  • Trapping and monitoring adults should be started early and continued throughout the season. Sticky Traps and Pheromone Traps can be used in different settings to attract and trap specific insects. Use the trapped adults to correctly identify the insect to be controlled.
  • For larvae currently damaging plants, Beneficial Nematodes mixed in an aqueous solution and injected into borer entrance holes can kill larvae within 48-72 hours. Application rates of the nematodes for this purpose are substantially higher than standard application rates.
  • Introduce Beneficial Insects when possible. Use a specific predator/parasite if you are targeting a specific species.
    • Introduce Trichogramma Wasp Egg Parasites into the growing area early in spring and once adult pests have been spotted. The Trichogramma will seek out borer eggs and lay their own eggs inside them stopping the growth cycle.
  • Thoroughly spray possible egg-laying sites with Horticultural or Dormant Oil sprays when adults are present and once the final frost has passed. The oils will smother the eggs and reduce borer populations the following season.

Click on the following for more information about specific borer pests.

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