Sawflies are winged insects, which look like flies but are more closely related to bees, wasps and ants.
The common name comes from the female’s saw-like egg-laying device (ovipositor), which is used to cut into the leaves where they lay their eggs.
Each sawfly species may have a number of different plant species it will attack, and several different species may attack the same plant.
The adult sawflies can measure up to 2cm (¾in) long, but most are around 6-10mm (¼-½in). They generally have black or dark coloured bodies. The female adult lays eggs in small to large batches, usually on the underside of the leaves, where they are easy to miss, usually from mid-spring to early summer.
The eggs hatch into larvae that look very similar to butterfly and moth caterpillars, which they are easily mistaken for, generally measuring around 2.5cm (1in) long. Slugworms are smaller. They can be white, grey, brown or black in colour or spotted with other colours. The larvae immediately start to devour their food source.
Some species have more than one generation of adults per year, so eggs can be laid at different times throughout the year. The gooseberry sawfly, for instance, has up to three generations per year, with larvae feeding from April to June, July, and August to September.
When fully grown, the caterpillar-like larvae stop feeding and pupate. Most drop to the ground, create asilk cocoon and pupate in the soil.