Advertisement I don't sterilize my communal enclosure substrate for various reasons, and so I get interesting hitchhikers showing up occasionally. I watch the whole operation like a hawk and remove anything that makes me nervous (so far in 2018 a tiny centipede, and a couple ants). Something I've been unsure about have been local harvestman species. I like what they add to the experience of watching the tank, so I've left them alone and watch them closely. I see they eat dog food and veggies and rarely engage with other animals (or each other). They're opportunistic scavengers, but I know some species can have predatory behaviors. I may have to remove them as they grow (I worry about any baby millies I might get). After about 6 weeks there've been no problems, but I wanted to ask the brain trust here if there's been documentation of them causing trouble for millipedes. The millies are the stars of the enclosure, though it also includes hisser roaches and fruit beetles. I noticed one of the harvestmen giving attention to a few millipedes. I've seen them meet up at the supplemental feeding dish, and then the harvestman will start exploring part of the millipede exoskeleton. I can't always tell what it's doing, but at times its pedipalps are in contact with the exoskeleton. I know pedes can become stressed by persistent tactile stimulation, and once I saw a smaller Ivory recoil and retreat. But the harvestman didn't persist and the Ivory settled down quickly. Interactions with the larger millipedes can last several minutes. I have a couple hefty Orthoporus (5+ inches long, and thick) who have been explored by harvestmen and seem to not notice (they continue eating or basking, don't recoil or react in any way I can see). What fascinated me most is that yesterday I saw clearly that the harvestman grabbed a mite from the exoskeleton of the millipede! It then moved away after no more than 5 minutes of interaction. The purpose of the tank is to experiment with keeping inverts communally, and figure out good combinations of species and best practices for keeping them together in ways that allow individual animals to thrive. So when I notice something interesting like this, especially interactions between species, I want to ask for input in case others have encountered similar situations or have other knowledge to share. I don't have photos of the harvestmen doing their business yet, but will add some to this thread as I'm able. Thanks!