An Arctic fruit fly relative called Chymomyza costata can survive being submerged in liquid nitrogen — that's -320 degrees F — and in previous research, Koštál et. al figured out they do this by accumulating an amino acid called L-proline in their bodies. In this new study, the Czech researchers fed fruit fly larvae a diet containing L-proline and glycerol, another cryoprotectant, and cooled them down. Treated larvae were able to survive after half their body water froze, which happened at 23˚ F (-5˚C). The flies were frozen for 75 minutes before being slowly warmed.