The saddleback caterpillar, a distinctive insect, often captures attention with its striking appearance. Its unique look frequently leads people to wonder about its development and what it ultimately transforms into.
Identifying the Saddleback Caterpillar
The saddleback caterpillar (Acharia stimulea) is identified by its characteristic markings. Its body features a bright green midsection, resembling a saddle blanket, contrasting with brown areas at both ends. A prominent brown oval, encircled by a white ring, sits in the center of its green back, creating the “saddle” effect. This caterpillar measures about 0.75 to 1 inch (1.9 to 2.5 cm) when mature. Its appearance, including fleshy horns and numerous stinging spines connected to venom glands, serves as a warning.
The Moth Revealed
The saddleback caterpillar undergoes a complete transformation, emerging as the Saddleback Moth (Acharia stimulea). Unlike its brightly colored larval stage, the adult moth has a more subdued appearance. The moth is dark brown with black shading and a furry body. Its forewings are dark brown to reddish-brown, featuring one to three small white dots near the base and apex, while its hindwings are paler brown. The adult moth’s wingspan ranges from about 1 to 1.7 inches (2.6 to 4.3 cm), with females being larger than males.
The Full Life Cycle
The life cycle of the saddleback moth begins when the female lays small, flattened eggs in clusters of 30 to 50 on leaves, which hatch into larvae after about 10 days. The larval stage, where the caterpillar feeds and grows, lasts four to five months, during which it undergoes several molts and its characteristic markings become more pronounced. Saddleback caterpillars feed on a wide variety of plants, including trees, shrubs, and garden plants such as oak, maple, apple, cherry, and corn. After reaching maturity, the caterpillar enters the pupal stage, forming a tough, spherical silk cocoon that incorporates some of its stinging spines. Pupation occurs on the ground or in leaf litter, where the insect overwinters in temperate regions before the adult moth emerges in the following spring or summer.
Encountering Saddleback Caterpillars
The spines of the saddleback caterpillar contain venom that causes an immediate, painful sting upon contact, leading to burning pain, localized redness, swelling, and a rash. Sometimes, more widespread symptoms like nausea or headaches may occur, so direct contact should be avoided. If a sting occurs, gently remove any embedded spines using adhesive tape, then wash the affected area with soap and water, and apply a cold compress or ice pack to reduce pain and swelling. While reactions are localized, individuals experiencing severe pain, significant swelling, or signs of an allergic reaction should seek medical attention. These caterpillars are found in gardens, on trees, and shrubs.