Behind Dr. Jane Robertson’s home and chiropractic business off Route 3 in Belfast, leafless fruit trees dot the backyard, and the side of her house is splattered with the bodies of caterpillars that she kills with a spray made of vinegar and dish detergent. But Robertson is all too aware of the many, many browntail moth caterpillars that are still alive and writhing in her trees, spreading their toxic hairs far and wide. “It’s emotional.