The saddled prominent, Heterocampa guttivitta (Walker) is a native insect which defoliates hardwoods in the Northeastern United States and Southeastern Canada. Outbreaks in both places were first recorded in the early 1900’s and happened at intervals of approximately 10 years since then. Populations are instable but build rapidly and without warning to outbreak magnitudes with large populations causing severe defoliation for 1 to 3 years until they suddenly collapse.
The insect is a late season defoliator; feeding heavily from late July to early September. While the defoliation in late summer is in general not considered serious, several periods of moderate defoliation (< 50 percent) can lead to some branch mortality and crown dieback. Similar damage can occur when a tree is heavily defoliated. Severe defoliation (> 50 percent) can lead to tree refoliation, even in late summer. However the new leaves are often killed by frost and very little regular bud growth occurs. Trees damaged and weakened by saddled prominent in successive summers can be killed by invading secondary pests. The saddled prominent can also affect forest recreation and maple syrup production.
While the caterpillars, or larvae, feed on the foliage of a variety of broad-leaved trees and shrubs, they favour American beech, sugar maple, yellow birch, and paper birch but they also feed on apple, cherry, mountain maple, oaks, poplar, and witch hazel. The saddled prominent has one generation each year.