Saddleback caterpillar

Systematic position. Acharia stimulea, commonly known as the saddleback caterpillar, is a member of the Limacodidae family within the order Lepidoptera. This species is native to North America and is infamous for its distinct, colorful appearance and painful stinging properties.

Biology and life cycle. The life cycle comprises four distinct stages: egg, larva, pupa, and adult moth. The larvae are the most prominent stage and are easily identified by their green, slug-like body with a brown, saddle-shaped marking on the back. They possess spiny protuberances that contain venom glands, which they use to deter predators.

Host plants. As a generalist feeder, the saddleback caterpillar has a wide range of host plants. It is commonly found on various deciduous trees and shrubs, including cherry, apple, plum, oak, maple, and rose, as well as several herbaceous plants like corn and sunflowers.

Damage and pest status. The larvae feed on the foliage of host plants, causing irregular holes and potential defoliation. While they rarely kill established trees, the primary concern is the danger they pose to gardeners. Touching the caterpillar causes immediate, intense pain, swelling, and localized skin irritation due to the toxins released by their spines.

Protection measures. Managing these pests requires a cautious approach:

• Manual removal: If the population is low, use gloves or tools to remove the larvae. Never touch them with bare skin.
• Biological control: Apply Bacillus thuringiensis (Bt) based insecticides to foliage to target young larvae.
• Chemical control: Utilize registered insecticides if infestations are heavy, focusing on spot treatment.
• Environmental maintenance: Keep garden areas weed-free to reduce secondary food sources and monitoring sites.