The caterpillars have two "color forms;" a dark form and pale form. Dark form caterpillars have a broad, "black-velvet" stripe running down their backs, and their sides are yellow to yellowish-white with black spots. Pale form caterpillars are light green or greenish‑yellow and may have a row of black spots down their back rather than a black stripe, or they may appear almost albino-like by lacking any noticeable black markings. There are two over-lapping generations per year in Ohio with large late instar first generation caterpillars feeding alongside early instar second generation caterpillars. Winter is spent as pupae buried 2 - 3" inches beneath the soil surface.