Maple twig borer
Proteoteras aesculana Riley
From: Solomon, J.D. 1995. Guide to insect borers of North
American broadleaf trees and shrubs. Argic. Handbk. 706. Washington, DC:
U.S. Department of Agriculture, Forest Service. 735 p.
Hosts. Maple, boxelder. Silver maple, boxelder, sugar
maple, and bigleaf maple have been listed specifically. Other maple
species are probably hosts (Craighead 1950, Powell 1962).
Range. Transcontinental in distribution across the northern
United States and south to Mississippi (Furniss and Carolin 1977, Powell
1962). Discontinuously distributed across Canada, from Nova Scotia to
southern Alberta (Prentice 1965).
Description
Adult. Small grayish moth with wingspan of 11 to 18 mm (Heinrich
1923). Forewings dark olive green mottled with yellow and gray and
sometimes small indistinct black markings (Forbes 1923, Miller 1987).
Larva. Pale white to gray, stout, and about 10 mm long when
mature. Yellow-brown head somewhat wider than long, averaging 1.1 mm wide,
with mouthparts directed forward. Thoracic shield yellow brown, often
darker laterally and posteriorly. Spinules on integument moderately dense
and dark (MacKay 1959). Poorly developed anal fork with 4 to 6 teeth.
(MacKay 1959, Powell 1962).
Biology. Moths fly from April to October in the northern United
States (Miller 1987). Moths have been collected in California as early as
February and as late as September, suggesting that this species is multivoltine
in the San Francisco Bay area (Powell 1962). Behavior is similar to that
of P. arizonae in California, except that larval tunnels are
somewhat longer (40 to 46 mm) and that they normally pupate outside of the
tunnels, presumably in leaf litter.
Injury and Damage. Larvae hollow out dormant buds and seeds in
fall and continue to feed on dormant buds in spring (MacAloney and Ewan
1964). During the growing season, larvae bore in the current year's
shoots, often killing them and preventing terminal growth. Frass, which is
ejected from the galleries, is mixed with webbing to form shelters around the
entrances. When terminals are killed, opposite lateral shoots begin
elongating and often produce forks or other deformities. Larval entrance
holes are typically present near the base of current season's growth. When
an infesation is sufficiently severe, trees become bushy and disfigured (MacAloney
and Ewan 1964). Large trees have been so heavily injured in early summer
in West Virginia that they appeared to have been damaged by heavy frost.
In the Pacific Northwest, 7 to 50% of bigleaf maple seeds have been destroyed by
this borer. Boxelders planted in nurseries and shelterbelts and as
ornamentals are often heavily infested in the northern Great Plains, as is sugar
maple in the northern Great Lakes area (MacAloney and Ewan 1964).
Control. Two species of hymenopoterous parasites--Elachertus
proteoteralis Howard and Scambus pterophori (Ashmead)--have been
recorded (Burks 1979, Carlson 1979). Removing and destroying infested
twigs in fall or spring, combined with foliar applications of residual-type
insecticides when moths are active, should help to prevent and reduce
infestation of high-value trees.
Damage. James Solomon,
USDA Forest Service. |
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