What Are Sawflies Learn to ID These Stingless Wasps

Sawflies dont have much of an identity of their own. As adults, they resemble flies or wasps, and when immature they look much like caterpillars. Theres no single neat and tidy taxonomic group to which all sawflies belong. Unless youre an insect enthusiast or perhaps, a gardener, you probably wouldnt know a sawfly if it landed on you. And if youve spent much time outside, one probably has! What Is a Sawfly? Theyre often described as stingless wasps. They get their common name from the females ovipositor, which unfolds like a jackknife. It functions like a saw blade, allowing her to cut into stems or foliage and deposit her eggs. People unfamiliar with sawflies may mistake this feature for a stinger, but theres no cause for concern. Sawflies are harmless to people and pets. Sawflies look somewhat like flies, but a closer look will reveal four wings, not the single pair that is characteristic of the order Diptera. Some sawflies mimic bees or wasps, and in fact, theyre related to both. Sawflies belong to the order Hymenoptera. Entomologists have traditionally grouped sawflies, horntails, and wood wasps in their own suborder, Symphyta. Sawfly Larvae Look Like Caterpillars Gardeners most often encounter sawflies when the larvae feed on their plants. At first glance, you might think youve got a caterpillar problem, but sawflies have behavioral and morphological differences that differentiate them from Lepidopteran larvae. If the larvae are all feeding along the leaf margins, and rear up their hind ends when disturbed, those are good signs that your pests are sawflies. Keep in mind that pest control products labeled for caterpillars, such as Bt, will not work on sawfly larvae. Most Sawflies Are Specialists Many sawflies are specialist feeders. The Willow sawfly, for example, defoliates willows, while several kinds of pine sawflies focus their feeding on pines. The table below lists some of the more common North American sawflies that might present problems in the garden or landscape, and their host plants. Within the 9 families of sawflies, we find some with unusual habits. Cephid sawflies live within the stems of grasses or inside twigs. Certain Tenthredinidae​ are gall makers. And perhaps the oddest sawflies of all belong to the family Pamphiliidae. These crafty sawflies spin silk webs or use their silk-producing glands to fold leaves together into well-camouflaged shelters. Common Sawfly Species in North America Common Name Scientific Name Preferred Host Plants black-headed ash sawfly Tethida barda ash columbine sawfly Pristiphora aquilegia columbine currant sawfly Nematus ribesii gooseberry, currant dogwood sawfly Macremphytus tarsatus dogwood dusky birch sawfly Croesus latitarsus birch elm sawfly Cimbex Americana elm, willow European pine sawfly Neodiprion sertifer pine introduced pine sawfly Diprion similis pine, especially white pine mountain ash sawfly Pristiphora geniculata mountain ash pear slug Caliroa cerasi pear, plum, cherry, cotoneaster, hawthorn, mountain ash red-headed pine sawfly Neodiprion lecontei pine, especially red and jack pine rose slug sawfly Endelomyia aethiops rose white pine sawfly Neodiprion pinetum eastern white pine willow sawfly Nematus ventralis willow, poplar yellow-headed spruce sawfly Pikonema alaskensis spruce, especially white, black, and blue spruce