From Dragon of Desire:

We also need more methods of taking out infestations. The bug bomb is nice, but it'd be awesome if you could add a Bug Missile that does the same over a wider area.

I was also thinking you could have some villager spawn eggs as quest rewards. Make the player have to protect them.

Also, if you do add HBM's nuclear mod, it has something called the Blue Rinse from Artemis fowl, that purges all organic mobs in the area. You could easily have that missile destroy infected blocks.