What modern insects are not flying or descended from flying ancestors? (I read somewhere that 99% are, so of course I instantly became curious which aren't. xD ) EDIT: Sorry, I should have been ...
Why are insects so energy-efficient while flying? Is it because of their light weight and aerodynamics or due to very efficient biochemical transformations (food->energy)?
How do dragonflies manage to fly at such high speeds without their wings collapsing? Their wings are thinner than paper, but they do not even flutter. What gives them their strength?