On large spruce trees, only the lower shaded branches are usually subject to attack. The top of an open-grown spruce receives enough sun, wind and direct rain splash to maintain an adequate check on mite population. Webbing of spruce spider mites is most obvious at the base of the needles soon after poplar trees have shed their cotton. Accumulations of poplar fluff in the webbing often make the webbing seem worse than it is. It is important to recognize that a few spider mites will be present in all gardens at all times during the growing season.
Mites only become a problem when their populations explode.
All spider mites are soft-bodied, small and very slow moving. As such, they represent an excellent food source to a wide array of carnivorous insects and predatory mites. In gardens where very little insecticide is used, predator populations usually remain high enough to balance the spider mite population at an acceptably low level. However, pesticides kill predators as well as spider mites. If a pesticide is applied the moment a spider mite is suspected, predator populations are reduced, and spider mite populations are free to increase without restraint.