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Black Twig Borer Description:

Borers are chewing insects that chew and feed on the inner bark and/or wood of trees. They are typically larvae of beetles, but some are wood-boring caterpillars. Black Twig Borers are a species of the ambrosia beetle group that is small, round, and dark brown/black in appearance. They are typically found in southern states such as Georgia, South Carolina, North Carolina, and Florida.

Hosts:

Vulnerable landscape plants should be monitored closely for borer attacks. Southern magnolias are especially prone to black twig borers. Borers are particularly destructive to newly planted trees and those in poor health, but will also feed on healthy trees.

Biology and Symptoms:

Borers feed unseen inside branches and twigs of many trees, damaging the vascular system and disrupting the normal flow of water and nutrients. Common indicators of borer infestation may include:

  • Sawdust-like material and/or sap and resin oozing from small holes in tree trunks or branches
  • Bark that appears swollen, knotty and callused, possibly cracking and eventually causing small areas to break off
  • Discolored, undersized leaves in the upper part of the tree and dying branches

Management:

The best way to manage black twig borers is to help optimize the overall health of the tree through plant health care practices such as proper fertilizing, mulching, watering, and managing other insects and diseases. Specific treatment applications can be applied in the spring, depending on the geographic area and seasonal conditions. Another means of managing this pest is for an ISA Certified Arborist® to prune out infested limbs and properly dispose of them offsite.

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