Flower opens up to attract insect Insect climbs into flower insect eats sweet nectar at the bottom of flower Whilst it eats Pollen is rubbed on to it's body when it flies away and does it to another flower it pollinates.
There are several flowers which do this. The pitcher plant is a marsh plant which drowns then digests an insect. The most famous plant which is carnivorous is the Venus Fly Trap. It literally lures the insect then closes over it and digests it.