The mosquitoes individually were just C-ranked. But, combining their sheer numbers plus the buff received from the unknown creature that the duo came for, their threat level was enough to require the intervention of seasoned A-ranked adventurers.

Already anticipating this sort of situation, Myles immediately activated an artefact/device that would create a shield around him and Wilhelmina.

In any other circumstance, they could have used their swords to hack down this swarm. But that would be ...