A Canadian caterpillar now found in Pennsylvania can cause a nasty rash.A number of cases have been recently reported in State College and elsewhere in central Pennsylvania.The white hickory tussock moth caterpillar is to blame.The caterpillar's fuzzy black spines contain venom used to ward off predators. But it can also irritate human skin.State College resident Bryant Martin said he and his 5-year-old son learned that the hard way. The boy was letting the caterpillar crawl on his hand on Sunday and developed a rash minutes later.Dr. Joseph Betz of MedExpress says the rash is only temporary. Betz recommends treating it locally with calamine lotion and ice.