Sawflies are wasp-like insects that are in the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps.

The larvae of some species have anti-predator adaptations such as regurgitating irritating liquid and clustering together for safety in numbers.

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.

[3] 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.

The suborder name "Symphyta" derives from the Greek word symphyton, meaning 'grown together', referring to the group's distinctive lack of a wasp waist between prostomium and peristomium.

[4] Its common name, "sawfly", derives from the saw-like ovipositor that is used for egg-laying, in which a female makes a slit in either a stem or plant leaf to deposit the eggs.

In his description, Gerstaecker distinguished the two groups by the transfer of the first abdominal segment to the thorax in the Apocrita, compared to the Symphyta.

[10][11] Symphyta are the more primitive group, with comparatively complete venation, larvae that are largely phytophagous, and without a "wasp-waist", a symplesiomorphic feature.

[17] More Xyelid fossils have been discovered from the Middle Jurassic and the Cretaceous, but the family was less diverse then than during the Mesozoic and Tertiary.

The subfamily Xyelinae were plentiful during these time periods, in which Tertiary faunas were dominated by the tribe Xyelini; these are indicative of a humid and warm climate.

[26] Early phylogenies such as that of Alexandr Rasnitsyn, based on morphology and behaviour, identified nine clades which did not reflect the historical superfamilies.

[36] Unlike most primitive insects, the sutures (rigid joints between two or more hard elements on an organism) and sclerites (hardened body parts) are obsolescent or absent.

The clypeus (a sclerite that makes up an insects "face") is not divided into a pre- and postclypeus, but rather separated from the front.

[44] The largest family, the Tenthredinidae, with some 5,000 species, are found on all continents except Antarctica, though they are most abundant and diverse in the temperate regions of the northern hemisphere; they are absent from New Zealand and there are few of them in Australia.

The next largest family, the Argidae, with some 800 species, is also worldwide, but is most common in the tropics, especially in Africa, where they feed on woody and herbaceous angiosperms.

[45] The larvae primarily feed in groups; they are folivores, eating plants and fruits on native trees and shrubs, though some are parasitic.

[52] Black grouse (Tetrao tetrix) chicks show a strong preference for sawfly larvae.

[55] Insects such as ants and certain species of predatory wasps (Vespula vulgaris) eat adult sawflies and the larvae, as do lizards and frogs.

[56][57] Pardalotes, honeyeaters and fantails (Rhipidura) occasionally consume laid eggs, and several species of beetle larvae prey on the pupae.

[5][58] In some species, the larvae cluster together, reducing their chances of being killed, and in some cases form together with their heads pointing outwards or tap their abdomens up and down.

Recorded parasitism rates in Europe are between 20–76%, and as many as eight eggs can be found in a single larva, but only one Collyria individual will emerge from its host.

[50] Outbreaks of certain sawfly species, such as Diprion polytomum, have led scientists to investigate and possibly collect their natural enemies to control them.

These parasites have been used in successful biological control against pest sawflies, including Cephus cinctus throughout the 1930s and 1950s and C. pygmaeus in the 1930s and 1940s.

[64][65] Like all other hymenopteran insects, sawflies go through a complete metamorphosis with four distinct life stages – egg, larva, pupa and adult.

The lifespan of an individual sawfly is two months to two years, though the adult life stage is often very short (approximately 7 – 9 days), only long enough for the females to lay their eggs.

[70] The giant woodwasp or horntail, Urocerus gigas, has a long ovipositor, which with its black and yellow colouration make it a good mimic of a hornet.

However, this is not practical or useful for some, thus the larvae can be quickly dispatched by simply dropping foliage into a vessel of plain or saltwater, diluted hydrogen peroxide or isopropyl alcohol, insecticidal soap, or other garden chemical.

In large-scale, industrial settings, where beneficial insect predators can also be used to eliminate larvae, as well as parasites, which have both been previously used in control programs.