From spring until the first frost, the wetlands of Canada swarm with blackflies. Some feed on nectar, others feed on blood. Most lay their eggs in water, some lay their eggs in flesh. Most of those that lay their eggs in flesh prefer dead flesh, but there is one species that prefers the flesh of the living.
The flies are small, so small that their ovipositors cannot pierce skin. They therefore lay there eggs in whatever soft tissue they can access: open wounds, open mouths, your sinuses, your lungs, your stomach. Throughout summer moose and deer wander the wilderness, snorting blood and larvae.