This was either in the new fern I'm repotting on my balcony or in the soil I'm using to pot it up. Is it a millipede? It's about 2.5 cm long when stretched out. Do I want to kill it or put it back on the soil? Presumably it has cohorts. Some previous postings on millipedes say they are ok, maybe even good; some have asked how to get rid of them and responses seem to indicate that would be reasonable; some are clear about not wanting them inside. What about on a balcony where the available food is limited? I have it under glass for the moment.
It seems to have two pairs of legs per body segment; so, that makes it a millipede. I encounter them pretty frequently in my garden, but not in large numbers. According to Wikipedia, some species will eat live plant matter; I would remove them from any plant containers.
Thanks very much. If it's still alive tomorrow, I'll take it outside. It's funny - I read one page that talked about how unappealing they are - emit poisonous or foul-smelling substances, with some releasing cyanide, can sting, discolour skin, What Is the Life Cycle of a Millipede? (the video is not directly related) and another that's all about how to raise them, how-life-cycle-millipede. They can live up to 10 years in captivity.
