Main Walkthrough

Location: Lostwing
Petitioner: Emile
Unlocked: Unlock Alliant Reports
Reward: 10 Sharp Fangs, 1 Black Blood

In order to reveal this side quest you must make your way through the first few tasks of Righting Wrongs, a mid-game, main story quest. You specifically need to speak to Otto, which will unlock the Alliant Reports feature in The Hideaway. Check in with Gaunte, right beside Otto, and you'll see Dying on the Vine listed.

Travel to Lostwing and go down the walkway to the right of the entrance to The Hanged Man. Inside a room on your left you'll find Emile, who is troubled by a pest issue. The vineyards of Lostwing are beset by wasps, and Emile wants Clive to get rid of them before they eat all of the grapes. Best help him out.

Head to Gaultand's Bales, the field area to the southwest of Lostwing. The Orabelle Downs Obelisk wil get you there in a jiffy. In the western field you'll find a small swarm of Vintner Wasps, and they will come at you from all angles. Deadly Embrace will pluck them out of the air so you can take them out on the ground. 

You'll receive Sharp Fangs and Bloody Hides for defeating the Vintner Wasps. Report back to Emile in Lostwing to resolve the matter and receive your reward.