Caterpillars are the larvae of butterflies and moths, which belong to the order Lepidoptera. Sawfly larvae look similar to caterpillars, but are an entirely different kind of insect. Sawflies are related to bees and wasps and belong to the order Hymenoptera. Like caterpillars, sawfly larvae usually feed on plant foliage. The sawflies captured in the pictures above were all feeding on the leaves of a potted oak tree growing in my back garden.

How can you tell the difference between a sawfly and a caterpillar?  One good way is to count the prolegs. Caterpillars may have up to five pairs of abdominal prolegs but never have more than five pairs. Sawfly larvae will have six or more pairs of abdominal prolegs. Another notable difference is that caterpillars have tiny hooks called crochets, on the ends of their prolegs. Sawflies don’t.

Another, less obvious difference between caterpillars and sawfly larvae is the number of eyes. Caterpillars almost always have 12 stemmata, 6 on each side of the head. Sawfly larvae usually have just a single pair of stemmata.