Gypsy Moths Less Hungry In '91

Smaller Numbers Mean Reduced Spraying

March 31, 1991|By Kerry O'Rourke | Kerry O'Rourke,Staff writer

Fewer gypsy moths are expected to chew on fewer Carroll tree leaves this year than last, a state pest expert said.

The state will spray about 1,400 fewer acres to suppress the insect in the county than it did last year, said Robert H. Tichenor Jr., chief of the Forest Pest Management Section of the Department of Agriculture.

Surveys done last fall found fewer egg masses were laid in the county than last year, meaning the potential for damage is less this year, he said.

The acreage sprayed will be in the southeast corner of the county, and about half the area will be in Patapsco State Park,said Betsie M. Handley, regional entomologist for the state in MountAiry.

About 80 households are in the area that will be sprayed, she said. Homeowners were sent letters informing them about the spraying in February, she said.

No one in Carroll objected to spraying on their property, Tichenor said. Spraying will begin in Maryland in early May, he said.

Planes will spray about 1,400 acres in Carroll;last year, the state

sprayed 2,866 acres here, he said.

The insects, while in their caterpillar stage, devour tree leaves. The oak,the most common tree in the state, is the pests' favorite food, Tichenor said.

The eggs, laid in July, probably will start hatching inthe county at the end of April, he said.

The population has declined in north-central Maryland and south-central Pennsylvania in recent years, but that doesn't mean the pests eventually will be eliminated, Tichenor said.

The gypsy moth is a hardy insect. It has survived in Europe for thousands, maybe even millions, of years, he said.

The moths migrated to the United States from Europe in the 1860s andhave been in Maryland only since 1971. State programs to suppress the insect began in 1982, Tichenor said.

The pest has done damage inMichigan, but generally has stayed east of Ohio, he said.

Centraland western Pennsylvania have been hit especially hard recently, Tichenor said. Last year, the pest damaged 4.4 million acres of trees inPennsylvania.

Five years ago in Carroll, the moths defoliated 4,393 acres. Last year, they damaged 200 acres, state numbers show.

The cycles -- the "ups and downs" -- are quick for gypsy moths, he said.

"Maryland still has lots of susceptible areas," Tichenor said.

The state has 2.7 million acres of forest. This year, about 160,000 acres of land will be sprayed, a decrease of about 15 percent from last year, he said.

Federal, state and county governments share the cost of the program. The total cost this year is $2.5 million.

The program escaped state budget cuts because it "apparently was considered a priority," Tichenor said.

Carroll will pay about 30 percent of the cost of the program, or $16,000. The payment covers the costof the survey done to determine areas where infestation could do damage and for spraying.

Two insecticides are used in Maryland to kill the caterpillars: B.t., or Bacillus thuringiensis, and Dimilin, or diflubenzuron.

Both chemicals are sprayed on tree leaves. Bt will be sprayed on all but 150 acres of the 1,400 planned for spraying; Dimilin will be sprayed on the rest, Tichenor said.

B.t. is a species of bacteria found naturally in many Maryland soils. Dimilin, which cannot be used near water, is a member of a group of pesticides called insect growth regulators.

Neither chemical has been found to have toxic side effects on humans, he said.

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