Hawthorn agrilus
Agrilus crataegi Frost
From: Solomon, J.D. 1995. Guide to insect borers of North
American broadleaf trees and shrubs. Agric. Handbk. 706. Washington, DC:
U.S. Department of Agricultural, Forest Service. 735 p.
Hosts. Hawthorn. Several unidentified species of hawthorn
are attacked (Chamberlin 1926, Fisher 1928)
Range. Reported from Pennsylvania south to Alabama, west to Iowa
and from Alberta and Quebec (Fisher 1928, Nelson and others 1981).
Description
Adult. Rather slender, elongate, very slightly flattened beetle
from 6 to 8 mm long (Fisher 1928). Greenish to brownish copper head.
Pronotum and elytra olive bronze, suffused with copper colors, becoming
distinctly reddish copper on apical third of elytra and moderately shiny.
Antennae serrate from fourth joint; pronotum wider than long; and elytra
slightly wider than pronotum at base.
Larva. White, elongate, moderately flattened, and 12 to 15 mm
long.
Biology. Adults emerge during June and July (Fisher 1928, Knull
1925). Young larvae bore into the cambium, where they feed and
develop. Larvae make meandering galleries, packed tightly with frass, that
initially extend downward, but many reverse directions one or more times,
usually for short distances. Completed galleries measure up to 2 mm wide
and sometimes reach 20 to 30 cm long. When mature, larvae burrow 2 to 5 mm
deep in the wood and form pupation chambers. New adults cut holes through
the wood and bark to emerge.
Injury and Damage. Removing bark reveals larval galleries in the
cambium. Bark immediately over the healed larval burrows swells, splits,
and puckers, making prominent bark scars. Although the bark scars meander
or zigzag crookedly over bark surface, they generally extend
longitudinally. Bark scars over multiple or repeated attacks may
crisscross many times and become very noticeable on the stems. Small
D-shaped exit holes can be found in the bark. Heavy infestations can
sometimes girdle and kill small plants. Some mortality in hawthorn
thickets in Mississippi has been attributed to this borer.
Control. Parasite larvae have been found in pupal chambers, but
no adults have been reared for identification. Direct controls have not been needed.
Damage in Creatagus. James Solomon,
USDA Forest Service. |
Damage mines on surface of sapwood. James Solomon,
USDA Forest Service. |
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