Host:  Ponderosa pine, white pines, and piñon

Symptoms/Signs:  Larvae feed on foliage and make large silken webs (tents) in the upper branches of host pines. Mature caterpillars are about 4 cm long, reddish brown to black in color and have tufts of black and yellow hairs on their back. Adult moths have dark forewings with large, white splotches and white hindwings.

Biology:  The tiger moth has one generation per year in the Southwest. Adult moths emerge and lay eggs in August. During September and October caterpillars hatch from eggs, begin feeding on pine needles and producing webbing. Larvae overwinter in the webs in groups. In April and May, larvae resume feeding and expand their webs. At this point the insects and the webs become very noticeable. In June pupation occurs.

Tiger moths are also found feeding and forming tents on Douglas-fir and white fir during outbreaks. It is believed that populations of this insect usually remain at low levels due to the action of predators, parasites, diseases, and cold winters.

Effects:  Larvae feed gregariously in webs primarily on young piñon and ponderosa pine. Although the webs and larvae can be very noticeable in spring, this insect causes minor defoliation. Permanent tree injury rarely results from feeding that is usually limited to the upper foliage.

Similar Insects:  Tents are similar to those formed by tent caterpillars such as the western tent caterpillar; however, L. ingens is the most common moth to make large tents on piñon, ponderosa, and white pines. Another species of tiger moth, L. argentata subalpina feeds primarily on juniper but occasionally on piñon in the Rocky Mountain region.

References:  23, 104