Western Tent Moths (Malacosoma californicum fragile) are the common, tent-forming moths in southern Nevada. Female moths lay about 200 eggs in one mass on their preferred host, which in southern Nevada is Desert Almond, but includes a range of shrub and tree species. The eggs overwinter on the bark of the plant, then hatch in the spring to coincide with the emergence of fresh leaves. While young, the caterpillars feed together and build their tent for protection from predators and the weather. As they grow, they enlarge the tent until the point that they are large enough to venture forth and feed alone on more distant leaves. The caterpillars mature in 4-5 weeks, and each spins an individual cocoon in which to pupate. They metamorphose for about 2 weeks, then emerge as adult moths, mate, lay eggs, and die as the cycle repeats.

For More Information: See the Butterflies and Moths website.

Adults are large moths with a wingspan to 1-1/2 inches (males) and 2 inches (females). Color ranges from dark brown to light tan, but the forewings have a pair of lines that are either darker or lighter than the wing color.

When they hatch, caterpillars are tiny (1/8 inch long) and dark with light-colored hairs. Mature caterpillars are about 2 inches long and variable in color. Most have a pale blue head and body, speckled with black, with a light and dark mid-dorsal stripes. The body is covered with orangish hairs tipped with white.