The rosy maple moth (Dryocampa rubicunda) is a silk moth in the family Saturniidae. Found throughout North America, this moth is not generally considered a pest, though its caterpillars have proven to be a nuisance to various maple tree species.
The rosy maple moth can be identified by its vivid colors. It is found in various hues, including creams, whites, pinks, yellows, and purples. However, the pink and yellow variation seems to be the most common. The adult moth is thick and fuzzy, with males displaying long, comblike antennae that allow them to detect the airborne chemicals (pheromones) that females give off to attract mates. Regardless of sex, the rosy maple moth is considered the smallest of the silk moths– adults are up to 2 inches across when wings are spread, and males are smaller than females.
The caterpillar stage (larva) of the rosy maple moth looks quite different from the adult, but it is just as visually striking. Also known as the greenstriped mapleworm, the caterpillar is bright neon green with faded white stripes and black dots running horizontally along its body. Its head is bulbous and brilliantly red or orange, with two thick antennae perched just above the head. Towards the rear, the caterpillar has a streak of red.
The rosy maple moth goes through five instars, or life cycles, from birth to death. Mating adults start to look for partners from early summer through fall. In South Carolina, mating occurs as early as March and ends in October. Once adults are ready to mate, the female moth will give off pheromones to attract a male. After mating, the female lays her eggs on the underside of the host tree’s leaves. The most common host species include sugar maple, silver maple, and red maple, although sometimes a turkey oak is also a host. Eggs are laid in a cluster, and young larvae usually feed together (this is called feeding “gregariously”). As they feed and mature, the caterpillars become solitary until it is time to pupate. Larvae crawl down the tree to the ground, where they will find a shallow hole or burrow into the soil to form a pupa. The pupal stage can last as little as two weeks or several months over winter. Most of its life is spent in this stage. Finally, the moth emerges from its cocoon, and the cycle repeats itself.
The rosy maple moth is not a particularly destructive pest. The larvae can damage maple trees, and in some cases, a single host tree may have hundreds of hungry caterpillars feasting on leaves. This does not generally harm the tree, but rather it may become an aesthetic issue since the tree may become partially or entirely bare. This defoliation may harm the tree if it is a sapling or otherwise stressed.
The rosy maple moth and its larvae serve as a food source for many birds, including tufted titmice, blue jays, and black-capped chickadees. Other predators include parasitic flies and wasps, and predatory beetles.
Management and Prevention
Although larval feeding generally does not cause any long-term damage, the feeding damage may be bothersome and aesthetically displeasing. Several contact and systemic insecticides (e.g., carbaryl, bifenthrin, spinosad) are effective against larvae, though this is very rarely advised or economically worthwhile. Before treating a tree chemically, consultation with an arborist or County Extension Agent is advised. Another way to inhibit the spread of the larvae is to prevent them from hatching by wiping the eggs off the underside of a leaf.