This is for arena.
The Killer Bees are fairly simple.
Each time you reach step 7 you check to see if the requirement for more strikes is met.
ATTACK ACTION
1. Declare Attack
2. Pay Costs
3. Roll to Miss
4. Avoid Attack
5. Roll Dice
6. Damage & Effects
7. Additional Strikes
8. Damage Barrier
9. Counterstrike
10. Attack Ends
Because the additional strikes occur before damage barrier and counter strike step, a full health Killer Bee Swarm can do a total of 4 attacks with 1 dice each against the same target.
You run the steps from 3 - 7 a total of 4 times (unless the bees somehow loses health in the meantime (can theoretically happen)), and on the 4th time there is no more additional strikes allowed so you proceed to step 8-10.
The Ants are less obvious. I dare say that they are a mess.
As written: They run step 1-7 instead of 3-7 when they choose a new target. And they leave the original sequence hanging for a later resolution.
In order to keep things simple i think it should be ruled that when they choose a new target in step 7 it follows the rules for sweeping, and the first sequence has all steps fully executed before a new sequence is started.