The gypsy moth, an invasive species, is widely recognized for its defoliating impact on trees. Identifying this insect at each stage of its life cycle is important for understanding its presence and potential effects on local environments. The appearance of gypsy moths changes distinctly as they progress from egg to adult, offering unique identification cues.
The Destructive Caterpillars
Gypsy moth caterpillars are the most noticeable and damaging stage. When newly hatched, they are small, dark, and covered in fine hairs. As they grow, they develop into a mottled yellow-gray color, reaching 1.5 to 2.5 inches when mature. A key feature is the distinct pattern of colored dots along their backs: five pairs of blue spots followed by six pairs of brick-red spots.
These caterpillars have bristly, tufted hairs. Early instars are small and dark, often appearing black. As they mature, their coloration lightens, and the characteristic blue and red spots become more prominent. While young caterpillars may feed day and night, older ones typically feed at night and seek sheltered areas during the day, often congregating on tree trunks or other outdoor objects.
The Adult Moths
Adult gypsy moths differ significantly in appearance between males and females. Female moths are larger, with a wingspan of 2 to 3.5 inches. Their wings are typically white or cream-colored, sometimes with faint dark, wavy markings or an inverted V-shape pointing toward the head. Female gypsy moths are heavy-bodied and generally do not fly, or fly weakly, often found near their egg masses.
Male moths are smaller, with a wingspan of 1 to 1.5 inches. They have brownish-gray wings with wavy dark patterns and feathery antennae, which they use to detect female pheromones. Unlike females, male gypsy moths are strong flyers, often seen flying in a zigzag pattern as they search for mates. Both sexes possess fuzzy bodies, but their differing sizes, colors, and flight capabilities serve as primary distinctions.
Other Life Stages
The gypsy moth’s life cycle also includes distinct egg and pupal stages. Egg masses are typically laid in late summer on tree trunks, branches, rocks, outdoor furniture, or vehicles. These masses are buff or yellowish-tan, have a fuzzy texture, and are covered with hairs from the female’s abdomen. Each egg mass is oval or teardrop-shaped, measuring 1 to 2 inches long, and can contain hundreds of eggs. Fresh egg masses are firm, while older, hatched masses may appear faded and feel spongy.
Following the larval stage, the caterpillar transforms into a pupa. Pupae are dark reddish-brown, hard, and shell-like. They often have a teardrop or barrel shape and range from 0.75 to 2 inches in length, with female pupae typically larger than males. Pupae are commonly found in sheltered locations, such as bark crevices or under loose bark, and may be held in place by a few silk threads. This stage lasts one to two weeks before the adult moth emerges.