Also, what could of made them molt this long?As Ivories tend to be surface active and you have surpassed the normal time a molt would take, I don't think it would be unreasonable to go through the substate. However, as I am sure you are aware, this does pose some risk to health if they are molting. Therefore, its really your call as to whether or not to take the risk. Millipedes almost always do best left alone. If you do decide to go through the substrate, do so extremely gently.
Sorry, I know that's not a straightforward answer, but it really is about what risks you are or are not willing to take in order to ascertain the health of your colony.
Could it be the room is to cold or hot? We have had some crazy temps. We try to keep in 68 in the house.It is possible that as the top layer of substrate runs out of nutrients, they simply burrowed in search of more. Millipedes will also burrow to regulate temperature, so it isn't always about molting, and so it is unlikely they have been molting this whole time. If you do go through the substrate and disturb them, I would simply re bury and let them find their own way to the surface if that is where they want to be. There's not much more you can do than that, if you decide to go searching.
Thank you! If we start keeping it warm in there, do you think they will come up to the surface?For Florida Species above 70 is normally best, so that may well be why they are burrowing. They are fully capable of surviving temperatures below 70, but if you would like to see them on the surface more you might consider investing in a low wattage heat lamp or a heat pad on the side (NOT THE BOTTOM) of the enclosure. Please note however, that this will likely require increased misting.
It's hard to say why else they might have gone under without seeing pictures of the enclosure and a description of care. It could be something wasn't right. It could be they are just moulting. If they are moulting and you leave them alone, they'll simply appear on the surface again at some point. If they are moulting and you disturb them, it might kill them or it might not. I tend to hold off digging for as long as possible.What happens if we leave them alone will they eventually stop molting? What if we go through the substrate and disturb them? How will I know they are sick if I disturb them?
Well everyone will think this is crazy but we found one and she seems fine. The other two millipedes are gone. We went through the substrate inch by inch and we can't find them. We never smelled anything bad. They can't get out. One was good size. The smallest and medium one are gone. We bought all these from bugs in cyberspace. The one we found is alive. We did find a little piece of like an exoskeleton. We are just going to give up and not get anymore. It is obvious we can't care for Florida Ivories.It's hard to say why else they might have gone under without seeing pictures of the enclosure and a description of care. It could be something wasn't right. It could be they are just moulting. If they are moulting and you leave them alone, they'll simply appear on the surface again at some point. If they are moulting and you disturb them, it might kill them or it might not. I tend to hold off digging for as long as possible.
Millipedes close to moulting often go floppy and inactive, so it can be difficult to know if they're about to moult or are sick. My main advice here is don't pick them up, prod them or touch them in any way. Just get a picture and ask for more help. Only pick up a sick millipede if you know what is wrong and have a plan that requires touching them.
Thank you for the well detailed reply. We do have leaves and wood in there but I haven't added any in months. I don't have coco fiber in this substrate. I did have just coco fiber and we had one Florida Ivory die, so I thought maybe that was it. The remaining Florida Ivory we had when the first one died did live until I guess now and what is really bad is the other one that died we didn't have for very long. A couple weeks before it went under with the other two. Why would one live and the other 2 die? Is it stronger? The one that lived came with the one that we had a couple weeks. So we have lost 3 Florida Ivories since June. I just don't think we are cut out for this.You're unlikely to smell anything if a millipede dies under the surface and the piece of exoskeleton suggests at least one has for sure (they break up into segments when they rot down). As for why, I can offer some suggestions.
Temperature: Could be your home is a little on the cool side. In which case, you might want to consider bumblebee millipedes (Anadenobolus monilicornis). I've had much more success with bumblebees in my cooler room. Your remaining Florida ivory could live with them. Bumblebees have a shorter lifespan, so you want to get a bunch so they can start a colony. They go under the surface more, but once you have a number, you'll often see them come up for food.
Dead Leaves: The surface looks pretty clear and I can't see any dead leaves. They need some dead hardwood leaves. Things like oak, beech, and so on... trees that drop their leaves each year. Don't add conifer needles or evergreens. It looks like you found some leaves before and know how to bake them, but this is a constant thing. Keep a covering of leaves on the surface and mix some new ones (crunched up) into the substrate when it's looking a bit clear. The surface leaves also give them some surface hiding places.
Calcium: This links to the leaves, as these provide calcium, but you can also provide a little extra calcium just to be sure. The powder they sell for reptiles works and there are various invertebrate foods that are rich in calcium. You can sprinkle the powders on things like cucumber.
Pesticides: They're sensitive to pesticides, so ideally use organic vegetables and wash everything carefully. Don't use fly spray or the like in the house. Keep pets that have flea or worm treatments away from the tank. Always wash your hands carefully before doing anything in the tank.
Coco Fibre: I see previously you were told this was bad, but I've used it for almost all my animals and not seen that. What it does need is to be mixed with other stuff to make it nutritious. I usually do half coco fibre to half dead crushed leaves and a sprinkle of calcium powder. This will be cheaper than buying ready mixed substrate.
Tank: Looks fine to me, though if it's as large as it seems, you could probably add some more substrate without risking them being able to climb out. This is not essential, but if you decide to go the bumblebee route, more substrate means more space for them.