# Spiny oak-slug moth (Euclea delphinii) > A small moth whose larva is a flattened, often brightly coloured 'slug' caterpillar with stinging spines that feed on oaks and other deciduous trees. Source: https://insectscanner.com/species/spiny-oak-slug-moth/ (updated 2026-10-10) ## Is it dangerous? **Stinging caterpillar.** Larvae have urticating spines that inject irritating compounds; contact can cause immediate pain, burning, redness, swelling and a localized rash that may last hours to a few days. Avoid touching caterpillars with bare skin. First aid: do not rub; remove spines by applying sticky tape, wash the area with soap and water, apply cold compress, and use topical hydrocortisone or oral antihistamine for itching. Seek medical care if reaction is severe, widespread, or if breathing difficulty occurs. **Pets:** Pets can be stung if they mouth or sniff caterpillars; reactions in small animals can include drooling, pawing at the mouth, facial swelling or vomiting. Keep pets away and seek veterinary advice for significant reactions. ## Quick facts - Scientific name: Euclea delphinii - Order: Lepidoptera (Moths and butterflies) - Family: Limacodidae (Slug caterpillar moths) - Size: 18-30 mm wingspan - Colours: Brown, Olive, Cream - Habitat: Deciduous forests, woodland edges, suburban shade trees and gardens where host trees (especially oaks) grow - Range: Eastern and central North America — from parts of southeastern Canada through much of the eastern United States - Active: Spring and summer (typically late spring through summer); adults are nocturnal and attracted to lights - Lifespan: Adults live for about a few days to a week; caterpillar stage lasts several weeks depending on temperature and food - Effect on plants: Leaf feeder - Pest: yes ## Overview Euclea delphinii is a species of Limacodidae (slug caterpillar moth) found across much of eastern North America. The caterpillars are distinctive: broad, flattened, often brightly coloured or patterned and covered with short, venomous spines or tubercles that can deliver a painful sting. Adults are small, stout moths that are relatively plain in appearance and are mainly active at night. The species is associated with deciduous woodlands and suburban trees where larvae feed on foliage. ## How to identify it Adult spiny oak-slug moths are small, stout-bodied moths with a wingspan typically under 30 mm; forewings are brown with one or two green patches and a rounded wing outline. The larva (caterpillar) is very distinctive: a broad, flattened, slug-like body with reduced visible prolegs, often bright green, yellow, brown or patterned, and covered with short stinging spines or knobbed tubercles arranged across the back and sides. When disturbed the caterpillar may curl slightly or writhe. - Look for broad, flattened slug-like caterpillars with short stinging spines — unlike typical caterpillars with conspicuous prolegs. - Larvae are often brightly coloured or patterned and move in a slow, gliding fashion. - Adults are small, stout, brown moths with green patches on the forewings and a rounded wing shape; they fly at night and come to lights. - If you find the caterpillar, treat it as a stinging species and avoid direct contact. ## Lookalikes - **Other Euclea species** (Euclea spp.): Many Euclea caterpillars look similar; exact species separation often requires careful comparison of colour patterns, spines and geographic range or examination of adults. - **Saddleback caterpillar** (Acharia stimulea): Saddleback has a distinctive saddle-shaped dark patch and more prominent dorsal white/green spot; both can sting but look different in pattern and shape. - **Other slug caterpillars** (Limacodidae family members): Other limacodid larvae share the flattened, slug-like look; habitat, host plant and specific colour pattern help separate species. ## Life cycle - **Egg:** Females lay flat, scale-like eggs singly or in small groups on host-tree leaves. Eggs hatch in a few days to a couple of weeks depending on temperature. - **Larva (slug caterpillar):** The feeding stage: a broad, flattened, slug-like caterpillar with stinging spines. Larvae grow through several instars over a few weeks while consuming host foliage. - **Pupa:** The mature caterpillar spins a tough, rounded silken cocoon on bark or in leaf litter, where it overwinters before pupating and emerging as an adult moth. - **Adult (moth):** A small, short-lived moth whose main role is reproduction; adults are nocturnal and are attracted to lights. ## Diet and predators - Young eat: Leaf tissue of oaks and other deciduous trees and shrubs - Adults eat: Adults probably do not feed much; if they feed they may take nectar or not feed at all - Predators of the young: Birds, predatory insects and parasitic wasps and flies (many parasitoids attack slug caterpillars) - Predators of adults: Bats, night-flying insectivorous birds and predatory insects ## Effect on plants and gardens Larvae feed on the leaves of oaks and a variety of other deciduous trees and shrubs (including maple, cherry, willow and others). Heavy local infestations can cause noticeable defoliation but are rarely fatal to healthy trees. ### How to get rid of it For occasional local outbreaks, hand-remove caterpillars while wearing gloves or use a stick to drop them into soapy water. In larger infestations, target larvae with biological insecticides containing Bacillus thuringiensis var. kurstaki (Btk) while larvae are small, or use registered insecticides labeled for caterpillar control on ornamental trees. Encourage natural enemies (birds, parasitic wasps) and remove overwintering cocoons. Avoid touching caterpillars directly. ## Where and when to find it Look for larvae on leaves of oaks and other deciduous trees; check trunks, branches and leaf undersides. Adults are found at night at lights. - Best time: Late spring through summer (May to August in much of its range); night for adults, daytime for larvae on foliage. - Tips: When photographing larvae keep a safe distance and use a zoom lens. If you must handle a caterpillar, wear thick gloves or use forceps and place it into a container to avoid being stung. ## Fun facts - Slug caterpillars lack the typical visible prolegs of other caterpillars and move with a gliding motion that looks slug-like. - Their 'spines' are actually hollow urticating structures that can break off in skin and inject irritating substances. - Despite their painful sting, they are part of a natural control balance and are prey for many parasitoids and birds. ## Frequently asked questions ### Do spiny oak-slug caterpillars sting? Yes. The caterpillars have urticating spines that can cause painful stings, redness and itching on contact. ### Do adult spiny oak-slug moths bite or sting? No. Adults do not sting or bite; only the larval (caterpillar) stage has stinging spines. ### Why is one in my house? Larvae feed on trees and woodlands; you may find wandering caterpillars on the ground or attracted indoors by lights as adults. Accidentally brought in on firewood, tree trimmings or outdoor furniture is common. ### How can I get rid of them in my yard? Remove or brush off caterpillars wearing gloves, drop them into soapy water, or use targeted biological controls such as Btk when larvae are small. For large infestations consult a licensed arborist or pest control service. ### Are they dangerous to children or pets? Only mildly. They are not deadly, but stings can be painful and irritating. Keep children and pets away from caterpillars and seek medical or veterinary advice for severe reactions. ### Where do they live? On deciduous trees—especially oaks—at woodland edges, parks and suburban yards across eastern and central North America. --- More about this species: [iNaturalist](https://www.inaturalist.org/taxa/136548), [Wikipedia](https://en.wikipedia.org/wiki/Spiny_oak_slug). Identify insects and spiders from a photo with the Insect Scanner iPhone app: https://apps.apple.com/app/id1543946563?pt=126685406&ct=web-markdown&mt=8 Identification from photos is never certain: don't handle insects you can't identify, and get medical advice for bites, stings or allergic reactions.