Most sawfly species are inconspicuous, and might be mistaken for flying ants. Different
species of sawfly attack different cultivated plants, i.e. they are specialist feeders.
The adult female has a saw-like ovipostor with which she makes slits, in which to place her eggs, in the plants that the caterpillars will feed upon. Gooseberry sawfly caterpillars not only eat the leaves of gooseberry bushes, but currants too, and they can completely defoliate them.
On any plants where there is a sawfly attack on the leaves,
either pick off the caterpillars by hand, or
spray with thiacloprid or use a biological control.
The apple sawfly lays eggs in the blossom in spring, and the larvae enter the developing fruit, causing it to drop prematurely. Plum sawfly larvae bore into the fruits with the same results.
Collect and destroy any infested fruits.
In areas where the pest is troublesome, spray immediately after petal fall to kill the young caterpillars before they have entered the fruit.