Greedfall is the latest RPG from The Technomancer developer Spiders, and it's filled with all manner of exciting quests to take on - but some are more tricky or confusing than others. There's an NPC with some trouble by the name of Constantin, and he'll give you the Greedfall The Suffering of Constantin quest - with at least one awkward part.
Constantin is, of course, your character's cousin, the governor of the island, and you've had to bail him out a few times already. You'll get his quest from New Selene, where he'll ask you for help in relieving his pain. The trouble comes with the way you'll need to make him better. This won't be just a short trip to the pharmacy... get ready to kill some bugs.
How to find all Tenlan nests and complete Greedfall The Suffering of Constantin quest
To help ease your cousin's suffering you'll first have to head to the Wenshaveye camp in the Wenshaganaw location, and the healer will send you to San Matheus to talk to the better healer Cecilius. You'll then have to go back to Wenshaveye village and talk to the hunter here. If you have level 1 craftmanship you can repair his weapon, otherwise you'll be tasked with driving off the local missionaries. Go to them, and you'll discover the missionaries think they're doing their god's work in ridding the island of the Tenlan creatures. Returning to the hunter, you'll get a way to find the creatures' nests.
Now here's where the trouble begins - there are four Tenlan nests in the local area, but only three count for the quest. There's a nest in the cave with a white Tenlan, where villagers have disappeared, but that doesn't count towards the 3 Tenlan nests you need to destroy - it's a separate objective! Here are the three ordinary nests you need to find first - thanks to Ogami on the Steam forums:
After all the nests are destroyed, including the white Tenlan's, you can return to the missionaries and get rid of them, then go to the village and inform the relatives - and the hunter. With everything in the area sorted, you can go back to Catasach the village healer and get him to help your cousin. You'll immediately get a cutscene with the healer helping Constantin - and the mission is complete! Hope this helps!