The pear slug or cherry slug is a sawfly larva. Aphids and sawfly larvae may attack the plant. Outbreaks of sawfly larvae can defoliate trees and may cause dieback, stunting or death. Prey selection depends on the species available but mostly moth and sawfly caterpillars are chosen. Such larvae are mainly seen in the sawfly suborder. The non-indigenous larch sawfly is the most destructive. The bushes can suffer from pests such as gooseberry sawfly and birds. The water figwort is host to the figwort sawfly whose larvae feed on the leaves. The spitfire sawfly ("Perga affinis", family Pergidae) is a hymenopteran insect found in Australia. Other potential threats are V-moth ("Macaria wauaria") and gooseberry sawfly ("Nematus ribesii"). English names include common gooseberry sawfly and imported currantworm. Cimbex femoratus, the birch sawfly, is a species of sawflies in the family Cimbicidae. In addition, Vallisneri worked to elucidate the reproduction of insects, specifically the sawfly. The oldest unambiguous sawfly fossils date back to the Middle or Late Triassic. They are not slugs but are a kind of sawfly of the family Tenthredinidae.