DULUTH — The Minnesota Department of Agriculture is preparing to treat about 1,200 acres in Duluth to slow the spread of a gypsy moth infestation.

Depending on the weather, officials are set to conduct the treatment on Thursday.

Last year, the department’s gypsy moth monitoring program detected a localized infestation of the destructive tree pest. The treatment area is located in West Duluth.

Officials plan to conduct two aerial applications of a bacterium over the same area, spaced five to 10 days apart. The bacterium has a low risk for humans or animals other than caterpillars.

As gypsy moth caterpillars eat the leaves, the insect ingests the bacterium, which stops the caterpillars from doing any more damage.