Like all insects, sawflies have three body segments and three pairs of legs. The head includes a pair of compound eyes, a trio of simple eyes (ocelli), antennae, and complete mouthparts. The thorax includes two pairs of wings and segmented legs. The thorax is composed of three segments, designated from front to back by the prefixes "pro-", "meso-" and "meta-". There is a pair of legs on each thoracic segment, and a pair of wings on the meso- and metathoracic segments. Most sawflies can be recognized by a pair of cenchri on the thorax.
Unlike bees and other Hymenopterans, sawflies do not have a constriction, or “waist” at the start of the abdomen; rather, the first abdominal segment is broadly joined to the postnotum of the metathorax. The abdomen has 10 visible segments, but sternite 1 is lacking, and tergites 9-10 are often hidden in males and often fused together in females. In most sawflies, tergite 1 (and rarely 2) has a center division line. Each leg has 5 tarsomeres, and in most sawflies, tarsomere 1-4 include a pad-like pulvillus. The apical tarsomere includes a pair of tarsal claws.
The sex of a sawfly can be determined without dissection by the apical abdominal segments and external genitalia. The female is most recognizable by the presence of an ovipositor, or “saw”, for which the insect is named. The so-called sheaths, paired processes that cover the ovipositor when not in use, are also readily visible.
The diagrams below show general diagnostic characters; more specific anatomy is included in the glossary and on the individual fact sheets where relevant.