Pest profile

Spiny Oak-Slug

Euclea delphinii · Lepidoptera: Limacodidae[2]

The spiny oak-slug is a stinging slug caterpillar, less venomous than the saddleback but still worth avoiding.[1]

Spiny oak-slug caterpillar, yellow-green with spiny yellow lobes and red spots, on a leaf
Spiny oak-slug caterpillar, yellow-green with spiny yellow lobes and red spots, on a leaf. (c) Evan M. Raskin, some rights reserved (CC BY) — via iNaturalist, CC BY 4.0

How to identify it

  • It's pale yellow-green with four dark patches of spines toward the rear and many spiny yellow or red fleshy lobes.[1]
  • Grown caterpillars have a brown area on the back, and color can vary a lot.[1]

Look-alikes

Look-alikeHow to tell them apart
Saddleback caterpillarThe spiny oak-slug is less venomous than the saddleback.[1]

Where it lives

UK Extension describes it among Kentucky's commonly encountered stinging caterpillars.[1]

US map: public records from 32 states since 1990 (GBIF).

Biology and life cycle

Young slug caterpillars may feed in groups, but older larvae feed alone.[1]

Grown larvae are usually found in late summer, with one generation a year.[1]

Damage and signs

  • It feeds on oak, beech, chestnut, willow, pear, bayberry, sourwood, wild cherry and other trees.[1]

Health risk

Touching the spines can cause itching, pain, swelling or blistering; very young, older or unwell people tend to react more severely.[1]

Control

Prevention

Most stings come from brushing against leaves where caterpillars feed; their bright warning colors help you spot them.[1]

Pesticides

Where many are near homes, schools or play areas, Bacillus thuringiensis or carbaryl products can reduce them; follow the label.[1]

Common questions

What should I do if a caterpillar stings me?
Pull broken spines out with tape, wash with soap and water, use an ice pack, and see a doctor if the reaction is severe.[1]
Is the spiny oak-slug as bad as a saddleback?
It's less venomous than the saddleback caterpillar.[1]

Sources

  1. University of Kentucky Entomology (ENTFACT), “Stinging Caterpillars (ENTFACT-003).” entomology.mgcafe.uky.edu/ef003 (accessed 2026-10-06)
  2. iNaturalist, “Euclea delphinii taxon page (order and family).” www.inaturalist.org/taxa/136548 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.