I know it is a bit of a dark topic, but it's something that we keepers run into quite often. As mantids get older they tend to start breaking down and it can be quite difficult to watch, so I figured we could share some euthanasia methods. I know that the squish, or freezer methods seem to be the two most popular on here, besides letting them pass on their own. A fairly quick method I've found involves filling a jar with 70% ethyl alcohol and popping that in the freezer. After a few hours the alcohol drops below the freezing temperature for water, but remains a liquid. Dropping that mantid into the jar quickly freezes the water in their body, allowing for a quick passing. It also helps in preserving the specimen if there are any plans for pinning later.