Grounded is filled with assorted bugs that can drop interesting and important resources. The Larva Spike 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 aggro to you, the rest will try to swarm you, 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, shoot the larva as you go, and 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 Larva Spikes that you need to make the Larva Blade.