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Adults are about ½ mm long.
They have eight legs and are yellowish-green when young. When mature and fully
fed, they are grayish-black with a tan area behind the mouthparts. Immature forms
are smaller and lighter in color. Eggs are oval to circular and reddish brown.
There are several generations a year. Eggs overwinter on bark and needles.
This cosmopolitan pest prefers spruce, pine, hemlock, and arborvitae. Cedar,
yew, larch, cryptomeria, dawn redwood, fir, Douglas fir, and false cypress also
may be attacked.
At the first sign of stippling on needles, tap branches over white paper
and count the dark, slow-moving spider mites. Note the presence of white, fast-moving
phytoseiid predatory mites and the minute, black lade beetle mite predators.
Concentrate monitoring activities from March through June and September through
November.
Spraying is not recommended unless stippling damage exceeds ten percent
of green foliage; more than ten spider mites, on the average, are tapped from
a tree's branches; and beneficial mites and beetles are not found in all branch
samples. Use dormant oil sprays when overwintering eggs are abundant. In the
growing season, use summer oil or insecticidal soap sprays if predator populations
are present. |
