Are they eastern tent caterpillars?
Contact with these insects is generally not harmful with a few exceptions. Some individuals may develop skin rashes or irritations from contact with gypsy moth hairs, including those on the outside of egg masses. Researchers have found that ingestion of eastern tent caterpillars only by pregnant horses can cause them to miscarry (mare reproductive loss syndrome). There is no evidence that ingestion of eastern tent caterpillars is harmful to humans or other animals.
