"At the current level of O2 in the air I don't believe that flying insects can grow as large as even a hummingbird" This got me curious. At a quick search, I f

"At the current level of O2 in the air I don't believe that flying insects can grow as large as even a hummingbird" This got me curious. At a quick search, I found out that there in fact is at least a species of flying insect larger than (the smallest) hummingbird: https://en.wikipedia.org/wiki/Gauromydas_heros https://en.wikipedia.org/wiki/Gauromydas_heros https://en.wikipedia.org/wiki/Bee_hummingbird https://en.wikipedia.org/wiki/Bee_hummingbird The insect grows up to 7 cm in length whereas the bird can stay less than 6 cm at adulthood. No information about the insect weight though (for a proper comparison).