I did like the whole reproduction system we had going with the wasps, and I'd like to incorporate that into the race the next time around. What we did was the queen spawned tame eggs every now and then. the eggs were considered animals so they could be penned/pastured, chained, whatever you wanted. When they 'hatched' (transformed) they turned into larvae, which had a single bite attack which, if not deflected or blocked, would kill them and give the subject a syndrome. After x time had passed, the host would be killed and the worker or warrior (or a 1 in 9000 chance of a queen) would be spawned. It was very dfhack intensive.
Another thing I liked about the insects was that it was very easy to fuck it all up in the endgame. Even your most powerful soldiers (barring creatures summoned from the depths) could and would be taken out by a competent dwarf with an axe. One thing the wasps could do was coat themselves in metals, be it adamantine, steel, copper, lead (if you wanted). I fondly remember sending my adamantine-coated soldiers against a squad of humans. Half of them died, two were injured (but recoverable thanks to the biomass tech) and three were unscathed. Ten humans lay dead.
Wasps are unique in that they are both over and under powered at the same time. One of their natural attacks, stinging, would paralyse the target for a good time. This meant that against early, unarmored enemies or animals, they were quite powerful. However, even copper armor would completely stop the sting of a worker-caste, and Iron would stop a uncoated soldiers stinger. Adamantine-coated wasps could puncture most things, however there was a brief window where the target could fight back. Due to the wasp's exoskeleton, they were extremely frail and one broken bone would KO them, an easy target for a human with a broadsword.
So growing your hive turned into an art form where you caught animals that were strong enough to survive the bleeding proc from the larvae bite, but not strong enough to kill all the larvae before they could bite. You could pit multiple larvae against the animal, but then the animal would bleed out twice as fast. It really was a task in and of itself, but profitable once you get your hands on it.
One last thing I did like was that if another queen showed up on the map, all wasps with line of sight of either queen loyalty cascaded. This turned a 1/9000 chance into an event. At the end of the loyalty cascade, you either had one dead queen and a lot of other wasps dead, or two dead queens and a lot of bugs dead and without leadership.
Hive-building was pretty cool. A wasp could turn a log into something like 8 blocks of paper cement. paper cement was ultra-light for use in construction, and strong enough to use for starting armor, although it didn't hold up against proper forged armor looted from invaders.
