You could still have them scattered about like you do currently. Just make variants of them based on random cool species/types like Murder Hornets, Emerald Wasps etc. To ensure variety, make the the game do a check based on the boss being beaten inside their fortresses. Example, the player always encounters the current wasps in the game first. After the bosses is beaten the game sees it and will spawn only the next variant afterwards, rinse and repeat until all types are beaten then at that point each hive can be generated at random.
Be sure these variants are actually different from the starter one and not just renames/reskins. Different bodies, different attacks etc. Also a nice touch would be what was mentioned in Oney's video where if you're wearing the head of a previous boss the game recognizes it and adds some cool dialogue