of Rhode Island GreenShare Factsheets
Japanese Cedar Longhorn Beetle
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
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.
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
By Lisa Tewksbury, 2000.
Photos by J.M. Fenglar, Connecticut Agricultural Experiment
courtesy of the National Plant Board
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information, call the URI CE Gardening and Food Safety Hotline
at 1-800-448-1011 or (401)874-2929 from outside Rhode Island;
Monday-Thursday between 9 am and 2 pm.
of Rhode Island Cooperative Extension provides equal program