Sawflies differ from other Hymenoptera families by having a large connection between the thorax and abdomen. The common name comes from the saw like ovipositor ⓘ, which the females use to cut into the plants where they lay their eggs.

They are mostly herbivorous and are the most primitive of the Hymenoptera, with a fossil record stretching back 200 million years. It is thought that the rest of the Hymenoptera evolved from a Symphyta species.

Some Symphyta species are a pest of agricultural crops.

Sawfly larvae are often called false-caterpillars: The number of pairs of prolegs enable one to identify these larvae caterpillars from those of the Lepidoptera caterpillars. Sawfly arvae has 6 to 9 pairs of prolegs whereas the butterfly caterpillars have less than 6 pairs of prolegs.