NC State Extension Publications

Description and Biology

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The dogwood twig borer, Oberea tripunctata, is a 1/2 to 5/8 inch long, slender, longhorned beetle that emerges from damaged dogwoods in late spring after the new vegetative growth has matured somewhat. These beetles fly to the new growth and chew a series of holes around the stem and then another series of holes one forth to half an inch away. Between these rows of holes the beetles insert an 1/8 inch long egg into the bark. Within a few weeks this egg matures and a slender, white grub hatches and begins to feed within the stem. As the grub bores downward, the stem dies and wilts above the area girdled by the beetle. The larvae bore downward and sawdust and other waste products and pushed out of holes along the stem. The grub eventually grows to about 7/8 inch long and overwinters in a cell excavated inside the twig. The following spring the grub matures and molts into a pupal stage. A few weeks later, a new generation of beetles emerges from infested plants to continue the life cycle.

dogwood twig borer

Dogwood twig borers are small, slender beetles.

dogwood twig borer ovip

Dogwood twig borers insert their eggs into twigs.

dtbl

Dogwood twig borer grubs are yellowish and slender.

dtbd McGraw

Typical dogwood twig borer damage.

Host Plants

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This pest is also know as the elm twig girdler. Elm, viburnum, azalea, and many fruit trees may be attacked by the dogwood twig borer, though its principal host is flowering dogwood. Infested branches often die or they are so weakened that they break off easily.

Residential Recommendation

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For control of dogwood twig borers, the plants can be sprayed in late spring with a pyrethroid insecticide to prevent the new generation of beetles from laying eggs. Infested stems can be pruned out as soon as wilting is noticed in early summer. Be sure to prune below the grub! These stems should be burned or otherwise destroyed to prevent the beetle grubs from surviving to produce more beetles next year. Fortunately, the dogwood twig borer is a sporadic pest so that treatment is probably not needed every year.

References

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For assistance with a specific problem, contact your local Cooperative Extension Center.

This Factsheet has not been peer reviewed.

Author

Professor Emeritus
Entomology and Plant Pathology

Find more information at the following NC State Extension websites:

Publication date: Nov. 18, 2013
Revised: Sept. 16, 2019

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