This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
Gooseberries, and sometimes Currants, are attacked by Sawfly larvae. The commonest of these is Nematus ribesii (fig. 373). Sawfly larvae are easily told by the number of their legs, there being six jointed ones in front and five pairs of prolegs, and in addition an anal pair. The larvae usually assume all manner of curious positions on the bushes.
The adult female Sawfly is about 1/3 in. long, almost orange, with dark head, and most of the thorax dark; the legs yellowish, except the tarsi, which are brown; the four wings are transparent and iridescent. In the male the thorax is nearly all black, except a yellow band in front, abdomen dark, except the apex and the sides and venter, which are yellowish. The adults occur in April and May, and lay their eggs in small slits on the under sides of the leaves. The egg stage lasts from five to twelve days. The larvae are green spotted with black, the first and part of the second segment and the last two orange yellow. When full grown, they reach nearly § in. long. At first the larvae eat round holes, then the edges of the leaves, and later the fruit may be attacked. When mature they fall to the ground and pupate in a silken case covered with earth; the pupal stage lasts ten to twenty-one days in the summer. The last brood that fall to earth do not pupate until the following spring.
Spraying with hellebore or dusting with the same was the old remedy. We now know that nicotine wash or paraffin emulsion will as easily kill the larvae, especially when young, but also up to at least two-thirds of their growth, and this is recommended especially where the fruit is going to be picked green. Even soft soap and quassia wash will kill them.