Advertisement My 4 year old daughter thinks bugs are the best, and after talking about it for months, we started a simple tank with Madagascar hissing cockroaches. It's really simple: cocosoft bedding, a heater that sticks to the outside bottom of the tank, multiple egg cartons to climb and hide under, mesh lid. We just had our fourth mysterious death today, and I need help! The first death was soon after we got our first cockroaches, and I attributed it to being dropped too often onto the kitchen floor, so we changed the rules about holding cockroaches (only on the carpet, only sitting down) and no one else has been dropped. The second death happened about a week after the first, and I didn't know what to make of it. The third death happened a week after that, and I removed the bark we had in the tank. My daughter had pulled thick, long strips of bark from a log the landlord left in our yard, maybe an oak tree, almost definitely some kind of hardwood. I thought that maybe, because the cockroaches didn't evolve around that kind of tree, they couldn't recognize it as poisonous even though it was really bad for them (although those trees are usually riddled with bugs around here, so it's not poisonous to all bugs). Then we didn't have any deaths for a week and a half after that, and I thought I'd solved the problem until just now, when we discovered one of the really big males, dead in his usual hiding spot. They don't show any signs of poisoning or illness. I just find them dead in the morning. They aren't wobbly or weak. The only thing that stands out behavior-wise is that I remember them being more active when I had a colony as a kid, but they run pretty fast when they are set down on the carpet, and climb around when they're not in their tank and at night. They are not dying of old age. The first three deaths were juveniles, each about 1 to 1.5 inches. They are eating "taste of the wild" dog food, and organic fruit and veg--grapes, tomatoes, spinach, carrots, apples, bananas and banana peels. They have plenty of water, and the tank is usually 70-80 degrees and 70-80% humidity. I'm going to relocate the survivors to a box and clean out the entire thing and start fresh tonight, soaking the interior walls with white vinegar to kill any mold or spores before I put them back in. Here are my ideas about what could be causing the deaths--I would so much welcome other suggestions, or advice from someone who has seen this before. - I got their 20-gallon tank from someone who used to keep fish in there. It looked clean, and the gravel that was in it was clean, so I dumped the gravel, wiped out the bit of dust that was in the gravel, and set it up for bugs. Could there be something left from the fishies that's making them sick? - Maybe something is wrong with the dog food (I mean, it's clearly fine for the dogs, but maybe hissers shouldn't eat it). When I had hissers when I was a kid, I remember feeding them only fruit and vegetables, but the care guides I looked at this time around all said they need a protein source and suggested dog or cat kibble. - We've had a full week of non-stop rain and 95-100 percent humidity, and now there's a little bit of stringy white mold growing in the cage. It only appeared today or yesterday, so I don't see how it could be related to the earlier deaths, but it made me wonder. Thoughts? What else can I do, besides rebooting the tank?