Maryland is doubling its effort to kill gypsy moths, an invasive Eurasian pest that defoliated tens of thousands of acres of trees across the state last year.
Airplanes are spraying pesticides on about 100,000 acres of trees in Baltimore County, Western Maryland and elsewhere. It's a $4 million project that state officials hope will beat back an egg-laying spree last year by the leaf-munching menaces.
"There are a lot of gypsy moths out there, and we are trying to suppress them so people don't have to deal with them in their parks or homes," said Steve Tilley, an entomologist at the Maryland Department of Agriculture.
By contrast, last year the state sprayed 50,000 acres. Contractors target residential areas with lots of trees that were stripped by the moths last year, spraying commonly used pesticides called Bacillus thuringiensis and Dimilin.
A drought last spring created an explosion in moth larvae, which are hairy brown caterpillars. The larvae devoured the leaves of 68,460 acres of trees last year - the most in more than a decade.
One of those whose property was swarming with the caterpillars last year was Mike Richardson, 40, a bartender from Baltimore County. His Freeland home had fuzzy invaders crawling all over it. They hit the oaks, white pines and sugar maples in his yard.
"I totally agree with the spraying because they do so much damage," he said. "If the larvae were to defoliate the area again this year, a lot of trees would die."
Gypsy moths, native to Asia and Europe, were brought to the U.S. in 1868 by a Massachusetts scientist who was trying to cross-breed them with silk worms.
The larvae escaped from Leopold Trouvelot's lab and started eating his trees. Because their hairy bodies are unappetizing to local birds, they have no natural predators. By the 1970s, gypsy moths were denuding trees from upstate New York to Maryland.
For more than three decades, Maryland has been spraying pesticides on the larvae as they emerge just when leaves first unfold on trees.
The high point of spraying came in 1990, when the state treated 187,000 acres. But over the past decade, federal and state funding for the fight against gypsy moths was slashed - until the state's boost this year.
Weather plays an important role in moth multiplication. Lots of rain encourages the growth of a fungus called Entomophaga maimaiga that kills the moth larvae. Last spring was dry, so little fungus grew - giving a green light to the moths.
