Bug Repellent maybe? And more dangerous bugs.
I enjoy having the sabiroids in my worlds but the fact that they can spawn literally inside my base really gets to me. It would be great if we could build some sort of block that prevents them from spawning in a certain radius around it. This block could have a customizable radius like the gravity generators and use more power the greater the radius. At the same time it could act as a sore spot for the local wildlife and slowly fill an agitation counter (not visible to the players) which will eventually result in a large scale attack on the offending base by the sabiroids with the goal of knocking out the repellent block.
The attack will last a variable amount of time and then the sabiroid spawns will return to normal ambient levels. The spawns will also return to normal upon destruction of the repellent block but of course this will mean that the sabiroids can once again spawn inside the base perimeter.
Another nice touch would be new forms of sabiroid. The current form could essentially be a worker variant. Change nothing. New forms could include:
Warriors: Larger and more dangerous than workers. Might also be faster. Distinctive colours. Seldom spawns outside of a base attack situation.
Archers: About the size of a wolf with a flea-like jump ability to aid in gaining the high ground. Can spit corrosive acid at players over a sizable distance but can't damage large blocks at all. Seldom spawns outside of a base attack situation.
Bombardiers: Large, slow moving siege bugs. Capable of hurling explosive bio-bombs which can destroy base defenses and down aircraft which get to close. Seldom spawns outside of a base attack situation. Limited number will spawn during a base attack.
Of course I'd settle for just the bug repellent block at this point :P