One of the challenges that BURG.L can give you in Grounded is to find some Acid Glands. The Acid Gland will drop from Larva, and you will need it to build the Larva Blade.
Where to find Larva
You can find Larva to the northwest of Spade Gulch. Head to the area marked on the map, then look for a tunnel the burrows underneath the ground. Down in this deathtrap is where you will find the Larva.
How to fight the Larva
There is no such thing as fighting one Larva. When one of the aggros to you the rest of them will try to swarm you as well, so prepare for a battle. You definitely don’t want to fight them down in the tunnel, as they will just run you over and kill you. Make sure you have a bow and plenty of arrows, then slowly move down the tunnel and shoot he first Larva you see.
Back out of the tunnel, shooting the larva as you go, then prepare to do your best job of kiting the enemies. Find a twig or boulder to stand on, and continue to shoot them. If you need to fight them on the ground, make sure you use the spear, landing one or two shots, then allowing your stamina to recover so you always have enough energy to run if you need to.
When you have all the Larva killed, loot the bodies to get the Acid Gland that you need to make the Larva Blade, and for BURG.L’s challenges.