War against the gypsy moth begins this week

(Harrisburg) — In an effort to protect wildlife habitat, the Pennsylvania Game Commission will spray for gypsy moths on more than 23,907 acres of state game lands beginning this week. 

Spraying will occur on 14 different state game lands, in areas identified as having the greatest need for treatment to prevent defoliation and tree loss due to gypsy moth damage.

“Those participating in spring gobbler season might encounter helicopters or other aircraft spraying state game lands or other forested areas,” said Dave Gustafson, Game Commission Chief Forester.  “We want those hunters to rest assured that the spray – Bacillus thuringiensis (Bt) – is not harmful to humans, and it usually only takes a few hours to complete each spray block.”

The spraying follows a 2016 statewide inventory of gypsy-moth impacts that detected defoliation on more than 15,000 acres.

“This year, we are spraying additional acreage beyond what was actually defoliated last year,” Gustafson said. “Based on the egg mass counts in 2016, we anticipate some local gypsy-moth populations are growing again, and we want to be proactive to prevent a population build-up that would result in similar defoliation and loss.”

The game lands to be sprayed were selected based on the importance of oaks there; whether they included existing Important Bird Areas, Important Mammal Areas or critical/unique habitats; their past gypsy-moth impacts and resulting forest-habitat conditions; and the financial values of timber stands there.

This year’s spraying will occur in the following regions: Southcentral, 2,611 acres; Northeast, 8,706 acres; and Southeast, 12,590 acres.  The Northwest, Northcentral and Southwest regions, which suffered little to no gypsy-moth defoliation, are not slated for spraying at this time.

Gustafson noted that previous gypsy moth impacts enabled a rapid transition of forest habitat types on state game lands, from mixed-oak to stands dominated by birch and maple, which are not nearly as beneficial to wildlife as mast-producing oak stands.

“In the 1940s, after the chestnut blight nearly wiped out American chestnuts, which provided the best and most reliable wildlife foods, oaks filled the void for wildlife,” Gustafson said.  “Unfortunately, in some areas, we now are seeing birch and maple replace the oak stands lost to gypsy moth defoliation.

“Prior to gypsy moth impacts, oak trees in Huntingdon County reportedly were producing 173 pounds of acorns per acre.  After gypsy moths, the same areas were yielding only 67 pounds of acorns per acre.  Seven of the eight lowest acorn production years occurred after gypsy moths hit the area, and 43 percent of oak trees were lost.”

Peter Sussenbach, director of the Game Commission’s Bureau of Wildlife Habitat Management said that, based on how valuable oaks are for wildlife on game lands, the agency simply can’t afford not to invest in spraying this year.

“We know mixed-oak habitats are important for all wildlife,” Sussenbach said. “Squirrel populations fluctuate with acorn crops. If acorn production is low, bears will den earlier, weigh less, produce fewer and smaller cubs and get into more nuisance situations. Deer reproduction and their survival over winter suffer when acorns are sparse. Neotropical birds, such as cerulean warblers, occupy habitats dominated by oaks. Wild turkey and ruffed grouse populations also depend on acorns.”