Impact of the Redheaded Pine Sawfly (Hymenoptera: Diprionidae) on Young Red Pine Plantations

The ecology of the redheaded pine sawfly was studied relative to its impact on red pine plantations. An ecological model, which formed the basis for socioeconomic analysis, was constructed. Because the sawfly prefers trees under moisture stress, damage is most severe in stands growing on sand blows, where there is competition for moisture from bracken fern and hardwoods, and where soils are too moist, too shallow, or too compacted. Outbreaks also appear to be related to dry years. The sawfly has a variable impact on multiple-use values. Because it injures the least productive trees in a stand, timber is only indirectly affected. Small openings created by tree mortality after an outbreak may provide edge \u27Wildlife habitat. The sawfly has both negative and positive effects on recreationists, depending upon the type of recreation; it may be a nuisance to campers, but may positively influence hunting. Preventive sawfly management involves proper site selection for red pine