Aerial treatments conducted by DNR’s Division of Entomology & Plant Pathology and Division of Forestry to slow the spread of spongy moth, which used to be called gypsy moth, in selected areas of Marshall, Noble, and LaPorte counties could begin the week of May 16, weather permitting.

The DNR says the Spongy moth is one of North America’s most devastating invasive forest pests and has caused thousands of acres of defoliation across the eastern United States.

Treatment begins shortly after sunrise but could be delayed until later in the morning or the next day due to unfavorable weather conditions like morning fog or rain. Treatment should take about an hour.

A yellow airplane flying 75-125 feet above the treetops will conduct the treatment starting at sunrise and continuing throughout the day as weather and flight schedules permit. Treatments may be completed by late morning or early afternoon.

The airplane distributes a spray containing the bacteria Bacillus thuringiensis var. kurstaki, referred to as Btk, into the treetops of infested areas where spongy moth caterpillars feed on tree leaves. Btk kills spongy moth caterpillars by disrupting their digestive systems after they ingest it.

The DNR stated, “Btk has been used for decades by organic gardeners and does not adversely affect people or animals. People who live or work near the treatment areas might want to stay inside when the planes are flying and for about 30 minutes after treatments are completed. This gives the material time to settle out of the air and stick to treetops. For more information on Btk, call toll-free at 1-866-NO-EXOTIC (663-9684) or call your county extension office.”

The DNR says ff the weather cools and slows the emergence of the caterpillars, treatment application could be delayed until the next week. Updates will be posted on Twitter @INdnrinvasive. DNR will also issue news releases to update the status.

Once treatment begins, rain or high wind may interrupt it. If that happens, treatment would resume the next suitable day and continue until all sites have been treated.

To determine if your property is in the treatment areas, to view maps of all treatment locations, or for more information about spongy moth, see