Kleptoparasitism (literally, parasitism by theft) is a form of feeding in which one animal takes prey or other food that was caught, collected, or otherwise prepared by another animal, including stored food. Examples of this last case include cuckoo bees, which lay their eggs on the pollen masses made by other bees, or the hosts of parasitic or parasitoid wasps. The term is also used to describe the stealing of nest material or other inanimate objects from one animal by another.

The kleptoparasite gains prey or objects not otherwise obtainable or which otherwise require time and effort. However, the kleptoparasite might be injured by the victim in cases in which the latter defends its prey. Kleptopredation is the practice of choosing prey that has recently fed.

More Info: en.wikipedia.org