Author: Eric Day, Virginia Tech
Dogwood, elm, hickory, poplar, apple, etc.
Description of Damage
Bark become cracked and scaly, trees loose vigor, foliage is dwarfed and spotted with yellow. In severe infestations may kill plant.
Scale cover resembles small oyster shell. The adults are usually clustered together and in severe infestations may cover the bark of infested branches completely.
Eggs laid in late fall, 40-150 per female. Hatching occurs in late spring. Crawlers move around 1-2 hours to 1-2 days before settling. The scales are white in color at first but become brown with maturity. They mature about the middle of July, mate, and lay eggs. This second generation develops and by late fall they lay the eggs which overwinter for the spring generation.
Sprays should be applied at time of crawler hatch and emergence from the old females, in mid-late May and again in late July or early August.
Populations tend to congregate on one or a few branches or on entire tree, seldom a few scales scattered over the host.