Written by David Doll (UCCE Merced) and David Haviland (UCCE Kern) As summer approaches almond growers need to be monitoring for webspinning spider mites.  The most common species during the summer are Pacific and twospotted spider mite, though on occasion strawberry spider mite can be found. As adults, all three mites look and behave similarly, even though control of Pacific spider mite is more difficult to control. Webspinning spider mites overwinter in the orchard under rough bark and ground litter. During the spring, usually in March and April, migration will occur from these places into the lower areas of the tree.  These early-season populations are typically small, do not reproduce quickly, and often become prey to early-season natural enemies.   However, as temperatures warm in late May through September, the populations increase rapidly, particularly if natural enemies are absent. In favorable conditions, a lifecycle can be completed in 7-10 days, with 8-10 generations a year. Spider mites damage leaves by sucking cell contents and damage initially appears as a light stippling. As populations increase, mites and their eggs become more visible, and eventually “webs” will appear around spurs and leaves. Leaves with high populations will fall from the tree, reducing carbohydrate production.  If leaf loss becomes severe there is a potential for crop loss the following year. Spider mites are most problematic in orchards that are dusty or where the trees are stressed.  Stressing factors can include insufficient irrigation, nutrient deficiencies, or excessive crop load. The most important factor in spider mite management is biological control.  When natural enemies are abundant, miticides are not needed.  When natural enemies are absent, control with even the best miticides can be short-lived.  The goal is to find a balance that relies primarily on natural enemies supplemented by miticides as needed. The most important predators