How to Identify Spiny Caterpillars

Take note of where the caterpillar is found. Location is an important step in correctly identifying caterpillars.

Identify the host plant on which the caterpillar is feeding. Different types of caterpillars feed on very specific plants.

Take note of the time of year the caterpillar is seen.

Look at the body color of the caterpillar. Io moth caterpillars exhibit an overall light green, with a narrow reddish line along each side. The buck moth caterpillar exhibits a brown to purplish-black back color with yellow spots. The saddleback caterpillar has a brown front and rear, with a green saddle marking its middle. Euclea caterpillars are a pale yellow to green color, with a brown back.

Look at the spines of the caterpillar. Io moth caterpillars are covered with branched, black-pointed, green spines. The spines of the buck moth caterpillar are branched and reddish, with red or black tips. The saddleback caterpillar has prominent spikes on both the front and rear of its body. Euclea caterpillars have a number of dark patches of spines near their rear end. The body of this caterpillar is also covered with many spiny yellow or red lobes.

Identify the plant on which the caterpillar feeds. Io moth caterpillars feed on numerous plants, including elm, oak, beech, ash, apple and willow. The buck moth caterpillar feeds on oak or willow trees and is seen in spring to midsummer. The saddleback caterpillar is found on deciduous trees such as chestnut, basswood, plum and cherry. Euclea caterpillars eat the leaves of bayberry, sour wood, wild cherry and pear trees.