ABOVE GROUND:
You have this idea, involving the grasshopper things you found. With a few changes, they could be realized into the caverns as a deadly swarm. After working on this idea for a little bit, you send several carriers out. However, it will be a while before they actually reach the caverns.
CENTRAL TUNNEL:
WOLFTOPUS GO!
Well, you can't say that you are at all surprised.
As such, the Primpsks have taken over the cavern, killing most of your drones, and cutting off the infected Primpsks. Luckily, the collectors you sent managed to get a bit of the firebug's DNA.
RIGHT TUNNEL:
Cut off from the hive-mind, the infected Primpsks can't drag a 'dead' combat drone into the city, so you just send a few by themselves, to figure out more of the language and to passively infect. The Primpsks guarding the entrance to the city barely look at the Primpsk drones twice. Since the Primpsks can climb along walls with ease, the city is very three dimensional.
The major economic production of the city appears to be all on one level, where carts and wagons can easily load and unload goods, and vendors can sell their wares. Every other part of the city is carved (The entire city is made of the bedrock surrounding it) around this level. Tunnels to upper or lower levels are everywhere, allowing for quick and easy access to everywhere else. The Primpsk drones spend most of their time on the main level, where there is more then enough to see. Your knowledge of the Primpsk language more than doubles (53%), along with the knowledge of Primpsk customs. Sadly, as far as you can see, the customs forbid any kind of contact that would allow you to passively infect, so you content yourself with infecting the creatures that the Primpsks live with, like this maggot:
Who labours as a draft animal, while the next creature is some sort of pest.
(If you want me to explain anything more about what you see, tell me. I don't think I've been all that clear.)
DRONES:
Advanced Scuttler: Stong, armoured, built to kill. Has incredibly fast, shrimp claws.
Scuttler: Armoured. Good all around. Shoots poison.
Gatherer: Make to collect and process DNA.
Light-bulb drone: Gives off light. Fast, but otherwise useless.
Scuttler Tank: Highly armoured. Not very fast.
Schoolbus: Carries crabs. Gives of light. Very large and heavily armoured.
Digger: Digs. Builds walls. Otherwise useless.
Primpsk drone: A Primpsk you control.
Primpsk Scout: Passively infects and scouts.
WOLFTOPUS: HALF WOLF, HALF OCTOPUS, ALL AWESOME.
Biter: Likes warmth. Hates cold. Adapted to bite onto things when it is cold.
Burrowing millipede: Digs. Biter dispenser.
EDIT: Added important things.