Contact your local county Extension office through our County Office List.

   
Planttalk Colorado™ is sponsored by Colorado State University Extension, Denver Botanic gardens, and the Green Industries of Colorado. For additional information on gardening, see Plant Select® and Extension Publications.

1417 – Tree Borers   Arrow divider image - marks separation between nested pages that are listed as breadcrumbs.

Raised areas of callous on birch trunk resulting from bronze birch borer tunneling

Borers, insects that develop underneath the bark of woody plants, attack many shade and ornamental trees. Most borers attack trees weakened by drought, mechanical injury, recent transplants, poor soils or root systems. The most important prevention of borers is keeping trees healthy through proper management.

Proper management includes watering trees long enough for moisture to reach the root system of the plant, wrapping young trees from November to April to prevent sun scald, and pruning dead or dying branches to discourage insects.

Banded ash borer tunneling in logSome common tree borers include lilac and ash borers, peach tree borer, mountain pine beetle and ips beetle, pinyon pitch mass borers and Zimmerman pine moth. The most common way to control borers, in addition to proper tree maintenance, is chemical control. But borers live inside trees, and treating them with insecticides is difficult. The best time to control borers is when adult are laying eggs on or under bark. Pheromone traps, available for some borer species, help determine if adults are present. Trunk sprays can be effective when borers are in the early larvae stage before they enter the tree.

For more information, see the following Colorado State University Extension fact sheet(s).

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