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Fighting Gypsy Moths

City plans to spray pesticides in Beverly Hills to combat “Lymantria dispar.”

In the scientific world, they are known as “Lymantria dispar.” But most people call them gypsy moths.

Originally introduced to North America in 1868, the microscopic pests create larvae that feed on several hundred different varieties of trees — defoliating them in the process. Healthy trees can usually withstand one or two consecutive defoliations of greater than 50 percent. But trees that have been weakened by previous defoliation, or been subjected to other stresses such as droughts, are frequently killed after a single defoliation of more than 50 percent.

“The larvae feed on trees in May or June,” said City Arborist John Noelle. “Their favorite species include oak, hickory, maple and beech.”

To fight the gypsy moths, the city government plans to spray a pesticide called Bacillus thuringiensis in the Beverly Hills neighborhood this spring. Known as B.t., it’s a naturally occurring bacterium common in soils throughout the world. During a December meeting of the City Council, Noelle told elected leaders that the city officials are planning an aerial application of the pesticide that would include 319 properties over 75 acres in the northeast neighborhood. He said that a 200-foot buffer zone would have to be created for any resident or property owner who objected to the insect-killing bacteria.

But too many objectors could destroy the program.

“If we have objectors at more than three locations, the program will become impractical and expensive,” said Noelle. “That’s the dilemma of the objectors.”

THE CITY HAS been using B.t. since 1988, when 1,200 acres were sprayed. The next year, officials used the pesticide on 1,800 acres. Since that time, the program has tapered off significantly: 400 acres in 1990; 200 acres in 1991; 100 acres in 1992; 96 acres in 1993; 57 acres in 1994; and 44 acres in 1995. In 1998, the last year the city used B.t., two trees were sprayed in a public right-of-way. For the past nine years, the city officials say that spaying has not been needed.

“The steady reduction of the gypsy moth population during the past several years has been attributed to the development of beneficial fungal and viral diseases, as well as insect parasites that were able to suppress the growth of the gypsy moth population,” wrote City Manger Jim Hartmann.

But the Northern Virginia region has experienced a growing problem with gypsy moths. Fairfax County is planning to spray 4,220 acres and Prince William County is set to use B.t. on 5,000 acres. Hartmann said that Alexandria’s suppression program was based on the results of an annual gypsy moth egg mass survey of 100 city sites that have historically experienced a problem with gypsy moth deforestation. Other than the problem created by the objectors, the only obstacle would be federal flight restrictions.

“The Transportation Security Administration will review the request and will approve or deny the request in spring 2007 at the time the state is scheduled to enter into a contract with a qualified aerial applicator company,” wrote Hartmann.

THE COST OF the program is set at $24,432 — $8,100 for an egg-mass survey; $3,366 for the aerial spray application; $1,000 for conferences and meetings; and $500 for mailings, notifications and supplies. Because the federal government is expected to kick in $11,466, the estimated cost to the city is $12,966. The section where the city wants to spray the pesticide is bounded by Chalfonte Drive on the north, Allison Street on the south, Old Dominion Boulevard on the east and Wellington Road on the west.

After several council members expressed a concern about potential effects of the pesticide during the December meeting, Parks and Recreation Director Kirk Kincannon conducted a study of B.t.’s effect on birds in the area of aerial application.

“Although their food resources may be reduced within the spray block temporarily, other food sources are available to the birds,” wrote Kincannon in a Jan. 11 memorandum to council members. “There is no evidence that any birds in this area are directly affected by the aerial application of the B.t. to control gypsy moths.”

Kincannon also warned that if the gypsy moth problem was untreated this year, the area that required pesticide would grow next year — increasing the number of bird habitats that would be disturbed by the program. The bigger problem, he noted, would be created by inaction.

“There is a real possibility that repeated tree defoliation by gypsy moths combined with the other environmental stresses such as drought could lead to a significant loss of trees, tree canopy, habitat for birds and other wildlife, and the loss of many other documented environmental, psychological and aesthetic benefits that trees provide the city,” Kincannon noted.

Neighbors will get a chance to express their opinions on the matter this weekend on Jan. 20, when the City Council will hold a public hearing on the spraying plan.