just an idea that came to my mind: if demolishers live literally traveling through lakes of lava, and their babies get born FROM lava... then they're resistant to fire... so it should be imposible to burn them normally.

maybe the correct way to KILL a larvae is to flash-freeze it (and then cut into tiny pieces so it can be converted into nutrients :D)
this would add a layer of danger to the mod, as players should be really careful when handling baby demolishers.

haven't unlock them yet, so i cannot relate if this behaviour is already in the mod.

EDIT: you could add it as a research after unlocking Aquilo, and by so, if players want to start farming demolishers very early, a possible hatch could become a new reason/incentive to go military science early on.

EDIT: aaaaand to prevent the very hate of some players for increasing the difficulty, add a migration in the code, so a disclaimer is shown the very first time the mod updates to the new version (or just hide this whole mechanic behind a start-up setting).