In the quoted line, I was thinking about trying to get photos of insects without a net, sitting on rocks, flowers, etc. like this observation, where the solution is following those steps.
I’m glad you raised the point about potentially injuring the insect with cooling. I included it in the steps because it’s effective and has been mentioned in topic: Tips/tricks taking pictures of bugs that move fast?
I’m not sure how relevant that paper is in this context since the idea with ice cooling in this context is to slow down the metabolism, not get anywhere near or below 0C, where ice crystalization can harm.
However, I take your point about whether it’s ethical to do that anyway, which is somewhat discussed in topic: Research and ethical questions in arthropod experience of “pain”