A new pest, the smaller Japanese cedar longhorn beetle, was found in Milford, Connecticut in the fall of 1998, attacking apparently healthy arborvitae, Thuja occidentalis 'Emerald Green.' Connecticut has issued an emergency regulation to prevent the beetle from becoming established in Connecticut. The regulation is to prohibit movement of infested materials and calls for the examination of nursery stock and regulated items by state inspectors. All infested trees will be destroyed to prevent further spread of the beetles.

This insect is native to China, Japan and Korea, where it is considered a secondary pest because it generally attacks weakened or newly-cut trees. In Connecticut this longhorn beetle has been found attacking the following plant species: Thuja occidentalis, Juniperus virginiana, Chamaecyparis nootkatensis and Chamaecyparis pisifera.

Description:

Cedar longhorn beetle adults range in size from 6 to 12 mm (1/4 to 1/2 inch) long. Males have iridescent, deep blue to black wings and females have red wings. Overwintering adults emerge from trees in the spring and mate on the surface of tree trunks. The females lay their eggs in tree bark crevices. Larvae feed under the bark, construct galleries and pupate within the galleries in the fall.

Adult smaller Japanese cedar longhorn beetle	Larva in cell under bark	Larval damage

Damage:

In April and May, look for adult beetles or the exit holes caused by overwintering adults emerging from trees. Adults are often found at the base of the crotch where two branches join. In late summer, the bark of infested trees often splits to expose sawdust-filled larval galleries. You may also see calluses on branches and tree trunks from the healing of wounds caused by larval feeding.

If you think you have found this beetle or signs of beetle damage, please call Lisa Tewksbury at the University of Rhode Island: (401)874-2750.

By Lisa Tewksbury, 2000. Photos by J.M. Fenglar, Connecticut Agricultural Experiment Station,
courtesy of the National Plant Board