Sawflies and their kin are wasp-like insects with about 8000 known species. Larvae often resemble moth or butterfly caterpillars but can be distinguished by the presence of at least six pairs of prolegs. These stumpy, fleshy structures extending from their rear abdominal segments disappear when they undergo metamorphosis and become adults. They’re much shorter than the three pairs of “regular” legs that the insects retain as adults, but they do help the larvae crawl around.
Although sawflies are in the same insect order as wasps, their larvae behave much differently. The larvae of most wasp species are maggot-like and feed on paralyzed arthropods provided by their mothers. Sawfly larvae, in contrast, are more like moth and butterfly larvae. They actively crawl around on their host plants and feed on the foliage. Most species of sawfly larvae are pretty host-specific; they only feed on certain plants. Knowing the plant a sawfly larva is feeding on can help identify the genus or species.
The individual shown here is a particular genus of argid sawfly (Hymenoptera: Argidae: Sphacophilus sp.) that was feeding on a hedge false bindweed (Calystegia sepium, Colvolvulaceae). I let these “weeds” grow up on a fence in my yard to see what they would attract, and this interesting insect was one of the rewards.