saw the bugger go into the bottle but snap too fast the mantis darted out. must try all over again.
a simple way is to use a glass bottle tie a string around its neck, put some bait in it and lie it horizontal on the sand bed. go do somthing for an hour and come back to check on it every now and then. when it is in the bottle, pull the string and make the bottle stand vertically, then it is quite hard for him to escape. and you can do whatever you want to it
chances are you will either catch him feasting on the bait of you will see the bait totally gone which means that it has already taken the food and left.