Maple trees managed for sap production remain part of a forest ecosystem. Forest ecosystems are complex communities of plants, animals and microbes all interacting with their physical environment and climate. Forests are especially competitive environments for trees that must attempt to maximize exposure to light, water and nutrients. One of the threats faced by maples growing in a sugarbush is from insects who feed on leaves. One of the insects that feeds on maple is called the saddled prominent. This insect feeds on leaves during its caterpillar stage. Like many insects, the populations of saddled prominent rise and fall each year with some years reaching severe or outbreak levels. The younger, reddish caterpillars have distinctive dark antler-like horns. Whereas the older caterpillars are smooth and have a distinctive saddle shaped marking on the back. Most maples can withstand defoliation caused by saddled prominent, but trees that have been defoliated repeatedly or those with predisposing stresses are more at risk to decline or mortality. According to the Department of Forest, Parks and Recreation:
Early August is a good time to look for saddled prominent in sugarbushes. The caterpillars feed through the first or second week of August, and then make their presence known as they crawl or drop to the ground to pupate.
While there have not been widespread observations of saddled prominent recently, there have been a few sightings. This is not especially surprising given that this insect has a history of appearing following outbreaks of forest tent caterpillar similar to the one Vermont saw recently.