The Indiana Department of Natural Resources on Wednesday finished its aerial spraying to slow the spread of the invasive gypsy moth, which can decimate trees and shrubs by feeding on their foliage.
Earlier this week, a yellow crop duster airplane distributed a spray containing the bacteria Bacillus thuringiensis var. kurstaki, or Btk, about 75 to 125 feet above the treetops of infested areas near Hobart in Lake County and in Union Township in Porter County. Btk works by killing gypsy moth caterpillars while they are feeding on the trees that are sprayed.
But further treatment will be launched in June as the DNR will spray mating disruption pheromones in parts of Gary, Portage, Valparaiso, and Chesterton, which have very low levels of gypsy moths. An area near Dune Acres was considered, but there wasn’t enough funding available.
The European gypsy moth was accidentally introduced to the U.S. in the 1860s, and since then, gypsy moths have spread throughout the Northeast and into parts of the upper Midwest and Great Lakes states including Indiana. The caterpillars feed on 500 different types of plants, but prefer oak trees. They can consume up to 11 square feet of oak foliage in their lifetimes. Trees can die within two to three years of an attack.
Indiana has been spraying for gypsy moths since 1982, but DNR State Entomologist Phil Marshall said the problem started getting significantly worse in 1992. Since 2000, DNR has participated in a national program — Slow The Spread — that analyzes gypsy moth catch data to decide the best way to treat an affected area. The program’s goal is to not let the gypsy moth spread more than six miles annually, which Marshall said Indiana has met and far exceeded for several years.
LaPorte County, for example, paced the state in gypsy moth catch data in 2014 — reporting 11,815 — so as a result spraying would have little effect on its gypsy moth problem. But the numbers in Porter and Lake counties — 822 and 92, respectively — are low enough to utilize a spraying program, Marshall said.
“If we find that a population is growing, we will treat it,” Marshall said.
Btk’s safety record with people and animals is said to be good, and it’s typically used by organic gardeners and occurs naturally in soil. For residents’ peace of mind, Marshall said, the planes don’t spray when school buses are in the area.
For more information, call 1-866 663-9684 or 1-888-398-4636. To determine if your property is in the treatment areas and for more information about gypsy moth, see gypsymoth.IN.gov. The DNR updates the public when it is spraying through the @INdnrinvasive Twitter account.