Hawthorne Agrilus
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Contents |
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.
Gallery
 Photo by James Solomon, USDA Forest Service, Bugwood.org |
References
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.
