- Armored scales have a hard and flat outer covering. They don’t produce honeydew.
- Euonymus scale: The adult male cover is long and white; mature males have two pairs of wings. The female cover is dark and oyster shell-shaped. The females and immature crawlers are yellow.
- Japanese maple scale: Male and female covers are oyster shell-shaped, differing only in size – females are larger, about 1/8-inch long. They have a white soft outer covering which can be easily rubbed off to expose a hard brown cover.
- Pine needle scale: Male and female covers are white and oyster shell-shaped, differing only in size – females are larger, about 1/8-inch long.
- San Jose scale: The adult female cover is round and about 1/16-inch in diameter; it is gray to brown with a yellow center. The male cover is elongate and somewhat oval. Overwintering crawler covers are gray with white central wings.
Biology and Habits:
- Euonymus scale females lay eggs under their shell. When they hatch, the crawlers emerge from under the shell several times per year from spring through summer. The scale-covered female is the overwintering stage. There are two to three generations per year.
- Japanese maple scale fertilized females overwinter under their covers. Crawlers are active from June through September. There are two overlapping generations per year.
- Pine needle scale females lay approximately 100 red eggs under the shell. The crawlers appear twice per year in late spring and mid-summer. The eggs are the overwintering stage. There are two to three generations per year.
- San Jose scale is a general feeder. Immatures overwinter on the bark under a cover. There can be as many as three generations per year.
- Euonymus scale: Euonymus, particularly winter creeper and Japanese; pachysandra and celastrus.
- Japanese maple scale: maple, firethorn, cotoneaster; elm, privet and apple.
- Pine needle scale: Austrian, Monterey, mugho, ponderosa, Scotch and white pines; spruces; fir; and hemlock.
- San Jose scale: firethorn, flowering fruits, rose and cotoneaster.
- Euonymus scale: Leaves develop yellow halo-type leaf spots. Branches and entire plants may die.
- Japanese maple scale: Light infestations cause leaf yellowing, however, as the infestation increases dieback may occur followed by plant death. Heavily infested bark appears gray.
- Pine needle scale: Yellowing, stunting, and dieback can result from several scales per needle. Tree death can occur from heavy infestations. Trees along roads and next to buildings are more severely affected.