Malacosma californica (moth),
Adult bodies are light brown, about 1/8 in. across. Forewings with two dark, oblique bands near center. Their eggs are laid in summer, encircling twigs with dark cementing substance; hatch the following spring and their larvae appear soon after first leaves begin to expand in spring. Body orange-brown with blue dots along each side of center; heavily coated with reddish-brown hairs. Construct tents of silk webbing around twig tips from which they forage for about 6 weeks. Tents enlarge as larvae grow. Mature caterpillarsare about 3/16 in. long. The pupae are formed within a heavy, silk-lined cocoon usually attached between bark crevices or in leaves webbed together. This process lasts approximately one month.
Oaks (Quercus agrifolia a favorite), madrone, redbud, hazel, ash, California holly, poplar, apple, almond, apricot, cherry, prune, plum, California coffeeberry, currant, and willow are favored hosts and are found throughout the United States: California. Favored by 30 degree days (at 65°F.). Cyclic, but related factors not understood. Webbing of branch terminals, chewing and exfoliation of terminal leaves. Heavy defoliation sometimes results, but resulting damage is of little importance since trees recover readily, especially if fertilized.
A single generation each year. Overwintering by eggs. Larvae hatch in early spring as new leaves unfold. Webs constructed by hatching larvae and grow with the larvae through 6 instars. Pupation in mid-summer, lasting about a month. Emerging adults mate and lay eggs in late August or September. Adults cluster around lights at night.