Mosquito
Mosquitoes of the genus "Toxorhynchites" never drink blood. This genus includes the largest extant mosquitoes, the larvae of which prey on the larvae of other mosquitoes. These mosquito eaters have been used in the past as mosquito control agents, with varying success.
Wyeomyia smithii
Wyeomyia smithii, the pitcher plant mosquito, is an inquiline mosquito that completes its pre-adult life cycle in the phytotelma—that is, the water contained by the purple pitcher plant, "Sarracenia purpurea". In this microcommunity of bacteria, rotifers, protozoa, and midges, "W. smithii" is the top-level predator; its presence determines the bacterial species diversity within the pitcher. It is not in any way a pest mosquito, neither biting nor approaching humans or livestock, although there are some populations in the southern US, such as that in the Apalachicola National Forest, that have been observed to take blood meals after laying an initial egg batch. In fact, it is the only known mosquito to have both obligatory biting and non-biting populations in the same species.