Moth infestation threatens Rhode Island trees

Moth infestation threatens Rhode Island trees

Gypsy moth egg masses can be seen below the shell of a caterpillar, left. (Breeze photos by Jackie Roman)

SCITUATE – Caterpillars, of all things, just might be the biggest threat to Rhode Island’s forests, say officials from the Department of Environmental Management.

Over the last several years Rhode Island’s population of gypsy moths has grown exponentially. This year the Division of Forest Environment estimates approximately 1.3 trillion caterpillar are expected to hatch.

“I can show you about 4,000 in one minute,” forest health program coordinator Paul Ricard said in an interview with The Valley Breeze & Observer.

Right outside of Ricard’s Glocester office on Putnam Pike, in a thicket of trees, is the beginning of a moth infestation. From afar it’s hard to tell that the towering pine trees are crawling with caterpillars but up close the problem is apparent. Almost every tree outside Ricard’s own office is dotted with white egg masses. Each egg mass contains as many as 1,000 eggs.

Around each egg sack, pin-sized caterpillars that have newly hatched can be seen. Though at first they are almost invisible to the eye, the caterpillars are impossible to ignore once grown.

Earlier this month, House Minority Leader Patricia Morgan posted a photo of a caterpillar-infested tree in the Warwick Mall parking lot.

The gypsy moth was first introduced to the U.S. from France in the 1800s when a budding entrepreneur thought the caterpillars could be raised as a silk worm alternative. Instead of producing silk, the caterpillars spread.

For years the population of gypsy moths was kept at bay by natural fungus, which would infect and kill the caterpillars. The only problem is that the fungus requires rain to germinate and unseasonably warm conditions have interrupted that process.

“We couldn’t predict this,” Ricard said. “The balance is extremely delicate.”

Ricard has studied the increase in caterpillars for years, documenting populations found on 142 plots of land across the state. According to his research, from 2005 to 2011 there was not a single egg mass counted on those plots. In 2013, there were nine masses counted. In 2014, roughly 33 were counted.

By 2015 DEM officials counted 3,500 masses. Last year that number hit 35,000. That’s an average of 11,000 egg masses per acre. And those are just the plots the DEM actually counts.

“I found gypsy moth egg masses just about everywhere I looked,” Ricard said.

The problem is exacerbated by the wind, which blows the hatched caterpillars everywhere. This means every tree, even those plotted in urban environments, is threatened.

All of this impacts Rhode Island’s trees because the caterpillars eat leaves, resulting in defoliation. When a tree is out of leaves, the photosynthesis process is halted.

Sometimes these trees try to regrow their leaves, using every bit of energy left to stay alive. But Ricard said this depletes the trees’ energy so severely that they are left vulnerable to natural viruses.

“All of these factors stress trees,” he said. “It’s basically a weakened immune system.”

The problem goes beyond Rhode Island. Some states have taken an aggressive stance against gypsy moth egg masses and authorized statewide pesticide spray program. Pennsylvania has initiated a “gypsy moth suppression program” that involves spraying 46,540 acres of land.

The Rhode Island Department of Environment Management, however, does not advocate for a statewide spray program. The spray does not guarantee an end to the gypsy moth outbreak.

“It has to be Mother Nature,” said Ricard.

Paul Ricard of the Department of Environmental Management points out several egg masses. The masses look like white fungi growing on the tree but contain hundreds of caterpillar eggs, eager to feast on tree leaves.


Remember 1981? THAT, was a gypsy moth invasion!