 The planes will target the cities of Cambridge, North Branch, and Hinkley, along with a few other areas in rural Pine County. State officials say the treatments have no known effects on humans, animals, or other insects, but may leave a light residue on vehicles and other items outside. That residue can be removed with soapy water. Spongy moth caterpillars are a destructive pest that can defoliate large sections of oak, poplar, and birch forests. I'm Andrew Krieger.