Most humans and elves dont have the mana capacity to fuel the growth of a tarnish wasp. The wasp will die to magical starvation, leaving behind an infected gemstone that can't be used as aethercite. Instead, it forms an entirely new class of magic destroying crystals known as Tarnicite. The site of the crystal cocoon often forms a permanent scar that reduces the person's ability to cast magic.
In experienced mages and in large magical creatures like a phoenix bird, the tarnished wasp will continue to grow, eventually killing its host. The eggs can grow very quickly overnight, and unsuspecting mages have been stung only to see a quickly growing ball of infected crystal the next morning where their arm used to be. If they are stung in the chest or head, they will die by the next day unless immediate action is taken.
When a tarnish wasp emerges as an adult, its only purpose is to find a male to mate with and then find a new crystal to lay its eggs in. The creatures wil occasionally pause their search to find food, which is almost always flower nectar or some kind of sugar so it can keep flying. Once the wasp finds a crystal, it will quickly dart in, inject a single egg, then fly away to find another.
The egg can hatch as quickly as a few hours, but sometimes it can take several weeks. At this point, the cycle starts over.
Shinny scary things, they are :D It's cool how there is a use for them, not despite the scary and the nasty but because of them.