Coleoptera, Lepidoptera, Hymenoptera


Borers are a group of insect pests that make destructive damage to trees and shrubs. The name reflects their boring larval stage feeding inside roots and branches or tunneling beneath the bark or into the wood. Many borer larvae will develop into beetles (such as wood boring beetle), moths (such as Squash vine borer), or wasps (such as seed borer wasps).

Life Cycle

All borers have four life stages: egg, larva, pupa, and adult. Eggs are laid on or under the bark, in cracks of tree trunks or branches. Once the egg develops and the larva hatches, it enters the host plant root or branch and begins feeding. To pupate, most borers drop into the soil. The adult emerges from the pupa and feeds on nectar or the leaves and edges of the foliage. After mating, the females fly to a suitable host and lay eggs on the bark, often in crevices or around fresh wounds. The time each borer spends at each stage can differ depending on the borer species, and environmental conditions.

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Most borers attack only certain kinds of trees, and some are attracted to a broad range of plants. Larvae in most borer species are the life stage that make serious damage to the plants. The larvae feed on the inner bark and then tunnel into the living wood. The feeding larvae destroy the tissues that transport food and water in the plant following girdling, branch dieback, structural weakness, decline, and eventual death of susceptible plants. Moreover, the wounds the borers make on aboveground, or below-ground plant organs facilitate the entry of plant pathogens that act as secondary pests into the host.



To prevent borer infestation, be careful not to damage the tree with a lawn mower or a string trimmer because trunk wounds are attractive to egg-laying adult borers.