The cute little green worms inching across yards and swinging from trees this spring are causing not-so-cute damage to trees in Southern Maryland.
The spring cankerworm, commonly known as the inchworm — a development phase of a small, gray moth, Paleacrata vernata — is experiencing a population explosion this spring, possibly due to a mild winter.
“Most trees can withstand being defoliated,” said Mark Muir, Maryland Forest Service Program manager for Charles and St. Mary’s counties. But some trees in Southern Maryland cannot withstand such a large population of the caterpillars.
Muir said a harsh winter would have frozen the ground, where the worm lives during cold months. The population would have been decreased as a result.
The damage has been worse in St. Mary’s County, where trees have no leaves because the worm has eaten them all. Muir said he got 50 calls in one day about the situation.
Karen Boling of Port Tobacco said that for more than two weeks, she and her neighbors have been fighting the little green worms.
“Port Tobacco is being eaten alive,” Boling said. She said she has lived in Charles County for 24 years and has never seen an infestation like the cankerworm. She considers them “a blight from God.”
She added that her maple and hickory trees are getting hit hard by the cankerworm.
“The leaves are just nothing but little holes, and I don’t know if they’re going to recover,” said Boling, who retired from a position with the government in October. Boling planned to make her yard “a work of art” this year, but the cankerworm is preventing her efforts.
Boling and her husband have observed the worms “all over everything,” including on the side of their house, in the trees in their yard and in the woods near their house.
An avid flower gardener, Boling said she has sprayed to dissuade the worms from eating her rosebushes, but she said they return by the next day.
She said she thought the worms were cute, but “I don’t think they’re cute anymore.”
“I don’t know what Mother Nature had in store for us this year, but she’s given us a real kick in the butt,” Boling said.
Humans cannot do much to dissuade the worm, according to Muir. Chemical sprays are neither cost-effective nor environmentally friendly.
By late May or early June, the spring cankerworms will return to the ground and leave trees with fewer leaves.
Trees that are already in a stressed state are more likely to die as a result of the defoliation, he said.
The cankerworm differs from other worms or caterpillars in that its life cycle is backward. While most worms become butterflies or moths later in life, the cankerworm is a moth before it becomes a worm.
“It’s a weird little critter,” Muir said.
In the fall, the cankerworm is brown.
“All they can do now is grin and bear it, is all I can say,” said Bob Tatman, Maryland Department of Agriculture’s Forest Pest Management Program manager. “It will be over soon.”
Tatman said tree leaves might be less green this spring, but he hopes that will be the extent of the damage caused by the spring cankerworm.
Trees that already have experienced stress may die as a result of the cankerworm’s presence, but most trees will have time to recover while the ground is not too dry and the air is not too hot.
The gypsy moth’s presence in June does not give trees enough time to recover before the heat of summer arrives.
The cankerworm’s harmful presence in Southern Maryland this spring is a preview of an expected invasion of the East Coast from Connecticut to North Carolina by cicadas.