Infestation of gypsy moths widespread | Maryland Gazette (HometownGlenBurnie.com)

According to the state Department of Agriculture, gypsy moths could be on track for one of the largest infestations in more than a decade. A survey last fall showed a high count of eggs for the gypsy moths, which ultimately can damage trees.

To prevent the eggs from turning into full-blown caterpillars and later moths, agriculture officials are spraying insecticides on nearly 100,000 acres, in spots stretching from Garrett County in the west to Talbot County on the Eastern Shore.

Eleven locations in Anne Arundel County were sprayed last week, including parts of Hanover, Jessup, Millersville, Severna Park, Crofton and the Hillsmere neighborhood near Annapolis.

The price tag for the spraying is $4.1 million and is being paid by local, state and federal governments.

The problem with gypsy moths is that they mercilessly gobble leaves, especially from oak trees.

"This thing is a leaf-eating machine," said Dr. Michael Raupp, a University of Maryland entomology professor. "It has evolved to consume entire trees through the gullets of these tiny caterpillars."

Just one larva can eat up to one square foot of leaves in one day, Dr. Raupp said. Since 1980, more than 1 million acres of trees have been defoliated by gypsy moths.

"The gypsy moth is by far the most destructive pest of forest and shade trees in Maryland," state Agriculture Secretary Roger L. Richardson said in a statement. "Through a combination of weather and an unpredicted rebound of gypsy moth populations, Maryland is seeing the highest levels of infestations since 1995."

The need for spraying has fluctuated in recent years.

In 2004, just 660 acres were treated and none were treated in 2005. Then in 2006, 25,454 acres were treated and last year about 50,000 acres were sprayed.

Dr. Raupp said it's not entirely clear why gypsy moth populations wax and wane. The moth population tends to move in cycles that range from five to 10 years, though the reasons are unknown.

One thing that is known, though, is that a fungal disease that harms gypsy moths, called Entomophaga maimaiga, helps keep populations in check. The fungus has been in decline in Maryland because of the prolonged drought.

Western Maryland has had a greater problem with gypsy moths than the rest of the state. The thick mountain forests have a high number of oak trees, and the western part of the state also started experiencing drought conditions before the rest of the state, Dr. Raupp said.

The Department of Agriculture claims a 98 percent effectiveness rate in killing gypsy moths with its spraying program.

Two sprays are used. One, called B.t., is made from a naturally occurring bacteria in soil. The other, Dimilin, is a manufactured chemical that prevents the moths from molting.

Meanwhile, a task force is scheduled to study the gypsy moth problem and offer recommendations to the governor and state lawmakers next year.

Information about the state's gypsy moth spraying program is posted at www.mda.state.md.us. Click on the gypsy moth link under "Hot Topics."