Mosquitos, dragonflies, bed bugs, they all have fairly short lifespans, right?

How possible would it be to artificially select for a breed of carnivorous insect to release on a population as a bioweapon? I'm not just looking to hurt people, but to really scare them shitless.

A viral pandemic is admittedly pretty evil, but doesn't really have the theatrics of a softball-sized bedbugs sucking all the blood out of a man, or a large dragonfly swooping-down and flying off with an infant.

It sounds better on paper than the mutant sea bass, at least.