Forest Huval, Ring, Dennis R., Reagan, Thomas E., Carlton, Christopher E.
The forest tent caterpillar (Malacosoma disstria) belongs to the family Lasiocampidae. The caterpillars are black, dark brown or gray, with broad blue longitudinal stripes and thin yellow stripes extending along each side. They possess a series of distinct white spots on the top (dorsal) midline, one spot per body segment. The sides are partially covered with fur-like long setae. Mature larvae are 2 to 2.5 inches (5.0 to 6.5 cm) in length. Adult moths are yellow or tan with thick, short, furry bodies. The forewings have two darker oblique lines near the middle. The wingspan is about 1.5 inches (3 cm). Egg masses are laid in shiny brown masses encircling stems and branches up to one-half inch (1.5 cm) in diameter. They are covered with a hard, shellac-like substance (spumaline).
Forest tent caterpillar, Steven Katovich, USDA Forest Service, Bugwood.org.
Forest tent caterpillars are known to consume the foliage of several tree species, including maples, gums, oaks, birch, cherry, elm, aspen and willow. The larvae hatch in early spring and reach maturity five to six weeks after hatching. The caterpillars are known for constructing silk mats on the branches and the main trunk. Larvae then pupate and emerge about 10 days later. The adult life span is about five days, during which mating occurs. The larvae develop inside egg masses for about three weeks. They do not hatch immediately but remain in the eggs until the following spring.
Egg mass, USDA Forest Service — Region 8, Southern, USDA Forest Service, Bugwood.org.
Adult, Lacy L. Hyche, Auburn University, Bugwood.org.
Control is generally not necessary. Hosts are seldom killed by defoliation. Populations tend to fluctuate with outbreaks occurring every several years. Heavy infestations of caterpillars can result in defoliation of trees. Damage to plants often looks worse than it actually is. Many trees are able to generate a new flush of foliage following defoliation, and variations in population densities mean many trees are not defoliated annually. The single generation annually means plants do not suffer from repeated waves of defoliation throughout the growing season. The feeding activities of larvae perform a valuable ecological service by recycling a portion of tree biomass back to the soil via their abundant droppings. These provide nutrients that promote herbaceous growth and improve overall floral diversity in forest and urban park ecosystems. Contact the LSU AgCenter and your parish agent for information on chemical control.