Little Green Caterpillars Threaten to Cause Millions of Dollars in Damage on Rhode Island


Luna Moth caterpillar 2007Rhode Island might have a big problem on its hands, but it’s in the form of a lot of tiny inch worms. State environmental officials are saying that throughout Rhode Island this spring, winter moth caterpillars are hard at work completely defoliating new trees.

The brown moths emerged by the millions this past winter in neighborhoods throughout the state. State forester Bruce Payton says that, “It is no coincidence that, in the spring, these same communities are seeing an astonishing number of caterpillars defoliating deciduous trees,” and adds that the number of caterpillars present right now is “astonishing.” The caterpillars, which are small, pale green, and have a peculiar “inching” form of motion, are eating beech, elm, maple, ash, oak, and even fruit tree leaves.

This little bug and its huge population growth is causing trouble for the entire state, and is putting many trees at risk. The bugs eat multiple small holes in leaves, which stresses trees into producing a second flush of growth right at a time when water preservation is critical. This can lead to millions of dollars in damage to both residential and farming trees.

The winter moth caterpillars are an invasive species that arrived from Europe about 80 years ago. For whatever reason, though, the past few years have seen the most issues with defoliation. In response, researchers from DEM, the University of Rhode Island, and the University of Massachusetts will be releasing a parasitoid fly into several Rhode Island communities this May. Known as Cyzenis albicans, this fly feeds exclusively on winter moth caterpillars. This is the third year of the fly program, and so far it has been effective at beginning to combat the raging caterpillar population.

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