" This simple fact explains an awful lot about the biology and conservation of bumblebees. They have to eat almost continually to keep warm; a bumblebee with a full stomach is only ever about forty minutes from starvation. If a bumblebee runs out of energy, she cannot fly, and if she cannot fly, she cannot get to flowers to get more food, so she is doomed "

― Dave Goulson , A Sting in the Tale: My Adventures with Bumblebees