Last year, arboretum staffers spotted eight caterpillars on a single tree but have not seen any sign of infestation this year, Danielson said. Still, the moths are coming. In 1998, gypsy moth traps, which exude female pheromones, caught 34 males. Last year, the traps snagged 220. Danielson said more traps have been set up around the arboretum this year and numbers will be counted in the fall.
Pesticides can help slow the spread of the moth as can natural enemies, including a European fungus.
Earlier this year, officials in Lake County said the fungus had killed off two populations of the moth, Cavanaugh said. Gypsy moths can be incredibly mobile, even as caterpillars. The moth larvae can spin a web of silk that allows them to be carried for miles by winds of 15 m.p.h. or stronger. The female moths also attach their egg masses to the wheels of cars, potentially enabling the insects to establish homesteads several states away, Cavanaugh said. But now we are at the point where the influx is so big it can't be handled.