Tree munching bugs out in force -- Gazette.Net


Now that leaves have returned to the trees, some insects are doing their best to eat them all.

There is a particularly heavy infestation of spring cankerworms in northern St. Mary’s, more than in the rest of Southern Maryland, said Mark Muir, forester with the Maryland Department of Natural Resources.

And the Maryland Department of Agriculture was scheduled to spray a localized section of southern St. Mary’s for gypsy moth caterpillars on May 3.

All this before an enormous, though harmless, brood of cicadas is due to arrive later this month after 17 years underground.

The little, dark-green cankerworms, commonly called inch worms, have been on a tear for the past week and a half or so, said Henry “Hank” Moulton of the Country Lakes neighborhood near Chaptico. Descending down on their strings of silk, there are little webs everywhere. “It looks like something out of a 1950s horror movie,” he said.

“We have a major infestation in our forest. They’re really going through the forest,” he said. Some new leaves have already been reduced to brown skeletons, he said.

But the worms are also crawling around on everything else — door frames, fence posts, dog houses, buckets and mailboxes in the neighborhood, he said.

Muir said the spring cankerworm is a native insect and not generally known for heavy defoliation, so there are no programs or plans to spray chemicals on them. For this year’s heavy population, “there’s really nothing you can do about it. You just got to let it run its course,” he said.

Healthy trees should be able to survive an early spring defoliation, but stressed trees may be killed, he said.

“While uncommon, it is not unheard of for populations of native insects to spike due to weather patterns or other environmental conditions,” he said in a statement. The mild winter may be the reason for the large number of cankerworms.

“Last year and this year was when we really noticed them,” Moulton said.

The juvenile cankerworms should be done eating by the end of May and will then go underground to pupate into moths later, Muir said.

Predators, parasites and diseases usually kill the non-native gypsy moth caterpillars, but when they don’t, the Maryland Department of Agriculture sprays for them by helicopter. In St. Mary’s County, about 68 acres around Route 235 and Bay Forest Road in the St. James area were scheduled to be sprayed on May 3.

The entire state is surveyed for high concentrations of gypsy moth caterpillars where they are prone to be destructive to trees, said Vanessa Orlando, public information officer for the Maryland Department of Agriculture. In southern St. Mary’s, “There were enough of them that they want to go in and get rid of them,” she said.

Gypsy moth caterpillars form nests in the forks of trees, protecting them from predators and extreme temperatures, as they defoliate trees.

The nests and caterpillars are similar in appearance to the eastern tent caterpillar, according to the U.S. Department of Agriculture. The insecticide for the gypsy moth caterpillars won’t kill the eastern tent caterpillars because they are too large right now, Orlando said.

Gypsy moth caterpillars prefer to eat all oak trees, apple, American beech, birch, sweet gum, linden, willow and Hawthorn trees, according to the Maryland Department of Agriculture.

The agency is preparing to treat more than 12,000 acres in the state, mainly in Garrett County in Western Maryland later this month.