Yield reduction is greater when infestations develop in the early squaring stage than in late stages of plant growth. Feeding usually occurs on the underside of the leaf where the mites pierce the epidermis and extract the sap. Infested foliage soon assumes a whitish or bronze appearance . The entire plant may die. The undersurfaces of the leaves usually have silken webs over which the mites crawl, though a heavily infested plant may have webs all over it.
Close examination reveals adult mites on the leaves.
Life history - Twospotted spider mites overwinter as females resistant to low temperatures. In mild winters, they may continue to feed and lay eggs. After the larval and each nymphal stage, there is a resting stage. Development is rapid in hot, dry weather. One generation may mature in as few as 5 days or as many as 20.