Adult Pacific mite females vary from slightly amber to greenish in color. Later in the season or under high population densities adult females can turn reddish. Upon emergence adult Pacific mites are almost void of food spots. As feeding begins usually two large diffuse spots appear forward and two smaller spots appear on the rear portion of the abdomen.
Pacific mite prefers the warmer upper parts of the vine.
Although it can cause damage early in the season, Pacific mite generally prefers the hotter, dryer part of the season. It is often considered an early season mite. It prefers the cooler parts of the plant and is found mostly in the shady parts of the vine. In certain areas and during certain years, populations can persist throughout the growing season. Willamette mite is primarily a problem in the Salinas Valley and Sierra foothill production areas where it can cause economic damage to varieties such as Zinfandel.