Sawfly

Sawfly Temporal range: Triassic–Recent PreЄ Є O S D C P T J K Pg N
Tenthredo mesomela
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Suborder:	Symphyta Gerstäcker 1867
Superfamilies
Anaxyeloidea Cephoidea †Karatavitoidea Orussoidea Pamphilioidea Siricoidea Tenthredinoidea Xiphydrioidea Xyeloidea

Sawflies are the insects of the suborder Symphyta within the order Hymenoptera alongside ants, bees and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay their eggs. The name is associated especially with the Tenthredinoidea, by far the largest superfamily, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera. The suborder Symphyta is paraphyletic, consisting of several basal groups within the order Hymenoptera.

The primary distinction between sawflies and their relatives – the ants, bees, and wasps – is that the adults lack a "wasp waist", and instead have a broad connection between the abdomen and the thorax. Some sawflies are Batesian mimics of wasps and bees, and the ovipositor can be mistaken for a stinger. Sawflies vary in length, most measuring 2.5 millimetres (0.098 in) to 20 millimetres (0.79 in); the largest known sawfly measured 55 millimetres (2.2 in). The larvae are caterpillar-like, but can be distinguished by the number of prolegs and the absence of crochets in sawfly larvae. The great majority of sawflies are plant-eating, though the members of the superfamily Orussoidea are parasitic. The adults feed on pollen and nectar. Predators include birds, insects and small animals. The larvae of some species have anti-predator adaptations such as regurgitating irritating liquid and clustering together for safety in numbers. Sawflies are hosts to many parasitoids, most of which are Hymenoptera, the rest being Diptera.

Adult sawflies are short-lived, with a life expectancy of 7–9 days, though the larval stage can last from months to years, depending on the species. Parthenogenetic females, which do not need to mate to produce fertilised eggs, are common in the suborder, though many species have males. Sawflies go through a complete metamorphosis with four distinct life stages – egg, larva, pupa and adult. The female uses her ovipositor to drill into plant material (or, in the case of Orussoidea, other insects) and then lays eggs in groups called rafts or pods. After hatching, larvae feed on plants, often in groups. As they approach adulthood, the larvae seek a protected spot to pupate, typically in bark or the soil. Large populations of species such as the pine sawfly can cause substantial damage to economic forestry, while others such as the iris sawfly are important pests in horticulture. Outbreaks of sawfly larvae can defoliate trees and may cause dieback, stunting or death. Sawflies can be controlled through the use of insecticides, natural predators and parasites, or mechanical methods.