The first time I saw these was in an old cooler full of water by my shed, there were 3 of them about 2 weeks ago. Now tonight I found one crawling up my door. Can anyone offer some insight? I have dogs and I'm horrified that it may be some kind of parasitic worm that they can contract.
This was observed in northwestern Pennsylvania, US. Rainy, cool fall weather currently, as it's the end of October. They're about 2 inches long. Very thin, blackish red in color and extra wiggly.