Infested trees may appear brownish-gray, and needle loss may occur. A hand lens will help you identify them. You may also be able to see eggs with a hand lens, which appear as tiny, shiny red or brown balls laid singly on the twigs and needles. In heavy infestations, webbing may also be conspicuous. Winter is spent in the egg stage in needle axils, under webbing on stems or branches, or under bud scales.
Hatching occurs in the spring.
Under optimum conditions, mites can complete their life cycle in ten days. Each adult lays 40-50 eggs, and there can be several generations per year. Control is generally recommended if you find an average of 5-10 mites per branch. Frequently, a second application 7-10 days later will be necessary unless the product is ovocidal. Early treatment, before populations build up, is most effective.