Sawflies are related to stinging insects like wasps but they lack a stinger. Their larvae emerge in early spring. With their rapid feeding, they cause extensive damage to fruit, leaves or needles on native trees. Adults can drill through the bark of trees and lay eggs in batches or on the underside of leaves. There are a wide variety of sawflies with common names reflecting their favored tree or shrub. Elm Sawfly, white pine sawfly, larch sawfly, dogwood sawfly and so on; there is a type of sawfly to feed on each of the many conifers, deciduous trees and shrubs. There is even an azalea sawfly. Host trees include willow, maple, birch, aspen, cottonwood and elm. Defoliation and death of limbs are frequently the types of damage inflicted.
Symptoms: Adults sawflies appear in May to June. Most sawfly larvae look like caterpillars but they have only three pairs of true legs, though they may have seven or more fleshy protuberances called false legs. Caterpillars will have fewer than five pairs of false legs. Leaf damage may include holes or skeletonized leaves.
More information: University of Minnesota Extension