Thanks to WSDA’s consistent trapping and eradication efforts, spongy moths are rare in Washington. Because of this, it is unlikely that current spongy moth populations will leave significant signs of their presence, such as defoliation or caterpillar droppings. Instead, you must look for the moth itself at its various life cycle stages. Below you will find detailed information on how to identify spongy moths as well as common imposters. For more information, you can watch our spongy moth video.
Female Adult Spongy Moth
Female spongy moths are a light cream color with wide abdomens and short, thin antennae. Their wings have brown zigzag stripes. European females do not fly, while Asian spongy moth females can.
Generally seen July to October
Male Adult Spongy Moth
Male spongy moths are darker and smaller than the females. They are a tan brown color and have dark zigzag markings on their wings. They also have distinct, hairy antennae which they use to located females by scent.
Generally seen July to October
Spongy Moth Egg Masses
Females lay distinct, fluffy egg masses that can range in color from brownish orange to off white. Each egg mass can contain 1,000 eggs or more. Egg masses are laid in late summer and overwinter to hatch late in the spring when trees have leafed out.
Generally seen July to May
Spongy Moth Caterpillars
Spongy moth caterpillars start out extremely tiny but rapidly grow up to 3 inches long. As they grow, they can be readily identified by their yellow head, hairy body, and distinct 5 pairs of blue dots followed by 6 pairs of red dots on their backs.
Generally seen April to July
Spongy Moth Impostors
The tent caterpillar is very common in Washington and is much less destructive than the spongy moth. Tent caterpillars produce large web-like tents each spring. Spongy moths do not build tents. Tent caterpillars tend to have orange and blue markings, lacking the distinctive blue and red dots of the spongy moth caterpillar.
Pacific Tent Caterpillar
Western Tent Caterpillars
Adult tent caterpillar moth and eggs
Female and male tent caterpillar moths
Tent caterpillar egg mass
Tent caterpillar "tent"
Fall Webworm
The fall webworm, as its name implies, appears in the fall and begins to feed on trees. They produce webs or tents much like the spring-feeding tent caterpillar. The caterpillars are usually brownish in color and lack the blue and red spots of the spongy moth. Adults are seldom mistaken for spongy moths, as they are white and lack markings.
Fall webworm on leaf
Fall webworms
Fall webworm web
Female fall webworm laying eggs
Fall webworm laying eggs
