NC State Extension Publications

Description

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The Japanese cedar longhorned beetle, Callidiellum rufipenne, is also called the smaller Japanese cedar longhorned beetle, the small Japanese cedar longhorned beetle, or the Japanese cedar longhorn. They are about 5/8 inch long. Japanese cedar longhorned beetle males are deep blue to black and have antennae longer than their bodies. Females have reddish brown wings and antennae shorter than their bodies. Mature grubs are legless and slender with constrictions between their abdominal segments so that their bodies vaguely resemble elongate rattle snake rattles. Grubs have a segment just behind their heads that is wide and somewhat flattened.

Japanese cedar longhorned beetles

Japanese cedar longhorned beetles are so called because they feed on Chryptomeria and have long antennae.

Japanese cedar longhorned beetle

Japanese cedar longhorned beetles are relatively small.

Japanese cedar longhorned beetle grub

Japanese cedar longhorned beetle grubs are pale and slender.

Biology

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Japanese cedar longhorned beetles have one generation per year. Females lay eggs in bark crevices over their 20 day life span. Females usually begin to lay eggs from 1 to 3 days after emergence from the host tree. Females seem to be able to lay eggs without feeding beforehand. The larvae bore into the bark and construct shallow galleries after hatching. They feed on the phloem and cambium layers. Then the fully mature larvae enter the xylem to begin pupation. They overwinter as adults and then chew through the bark to emerge in early spring.

Host Plants

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Larvae bore into coniferous trees of the cypress family. Major hosts include arborvitae, cypress, juniper, and cedar (Chamaecyparis). Young grubs tunnel just beneath the bark. These tunnels are packed with dark brown frass. Older grubs bore right into the wood and pack their tunnels with pale frass. New adult Japanese cedar longhorned beetles bore out of their host plant leaving a distinctly oval hole.

Japanese cedar longhorned beetle damage

Japanese cedar longhorned beetle damage to arborvitae.

Longhorned beetles chew oval exit hole

Longhorned beetles chew oval exit holes when they emerge.

Residential Recommendations

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Because Japanese cedar longhorned beetle grubs pack their tunnels with frass, spraying an infested tree is not likely to kill grubs inside. To prevent further attacks, plants in the cypress family should be treated with a pyrethroid in early March and again in early April. (Doing so will likely protect plants from cypress weevils as well.) Several pyrethroid insecticides are available in plant centers and big box stores (Look for an active ingredient that ends with "-thrin." Active ingredients are listed on the front often in very tiny font toward the bottom of the container.).

Other Resources

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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 & Plant Pathology

Publication date: Oct. 26, 2018
Revised: Sept. 25, 2019

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