Gooseberry sawfly caterpillar (Nematus ribesi) feeding on a redcurrant leaf. This insect is a common pest of gooseberries and related plants, and can strip the leaves from a plant entirely, ruining cropping. Despite the name sawfly, and the term caterpillar, it is neither a fly nor related to butterflies, instead being a hymenopteran, a relative of ants and wasps.