Do the nymph of the dragonfly moult?

Yes they do and they can kill u when they are adults.~

Only Dragonfly Nymphs turn into Dragonflies. It is only a silly story about them killing you, as they used to be known as Horse Stingers and people used to think that their bodies were giant stingers. They eat the Flies that are attracted to Horses, so that is why Dragonflies are sometimes near Horses.