When insects find their way into my home, I usually trap them in a glass & chuck 'em outside, opposed to squishing the poor buggers. However I sometimes forget, & when I return several hours later, to my dismay, they have croaked it. I don't understand. Shouldn't there be enough oxygen in a 500ml glass to keep a mosquito alive (for example) for way beyond several hours? I have observed this so many times. Not all of them die after a couple of hours, but I would say the majority do after 12 hours. What is killing these things? The only other things I can think of are heat, or even shock. However I live in a relatively cool climate (England), and don't leave them in direct sunlight.