Although sawflies are in the same taxonomic order as bees, wasps and ants, they have their own lifestyles and a rather different body structure that sets them apart, such that they are separated from the other species and placed within their own suborder Symphyta. The structural difference is that they have a broad connection between the thorax and the abdomen rather than a narrow 'wasp waist' that's normally associated with hymenoteran species. The common, collective name of sawfly is derived from the saw-like appearance and functionality of the female’s ovipositor, which she uses to cut into plant leaves and stems to lay her eggs.

 

Sawflies go through a complete metamorphosis with the four distinct stages of egg, larvae, pupa and imago (adult).

Typically, the adult female lays her eggs into a notch cut into a stem or the membrane of a leaf. A caterpillar-like larva emerges and feeds on the leaf of the host plant, undergoing several moults (instars) as it grows until it reaches the final non-feeding nymph stage. The nymph will either spin a silken cocoon in leaf litter or burrow into the soil to create a pupal cavity. Most species of sawfly overwinter in this form before entering a short pupa phase in the spring. The adults emerge a few weeks later and, depending on the species, may live only a few days, possibly up to three weeks or so at most.

 

As with most insect groups, individuals vary in size, shape and colour. The British List contains well over 500 species of which only a relatively small number are going to be of personal interest so, at present, I’ve earmarked four families with species that I may encounter – Cephidae (Stem Sawflies), Argidae (Fused-horn Sawflies), Cimbicidae (Club-horned Sawflies) and, by far the largest family, Tenthredinidae (Typical or Common Sawflies).

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Clicking any of the photos below takes you to a brief 'species account' that, in most cases, includes some information to assist with identification, and further images that can be enlarged.