I can’t remember who pointed this out to me, but it made me laugh. I present: The photo of a “wasp nest” that is actually a mantis ootheca.
Ootheca is a fancy way of saying “egg case.” Both roaches and mantids create egg cases, which is one of the reasons they are sometimes grouped together.
Check out this fascinating video of a mantis creating an egg case. (Interestingly, mantid egg cases are used in Chinese traditional medicine to treat urinary system problems. I have no idea how that connection came about.)
A mantis ootheca is not in any way like a wasp nest. The maximum size is about 1 inch in length (2.5cm). Yellowjacket and hornet nests can get very big–this one was about 6ft by 5 foot.
That’s hardly average–the nests I tend to get on my house seem to be about a foot or so before I clue in they are there–but big enough that using this photo deserves a bit of mockery.