Which is partly why lame plans like these usually get scrapped. Aside from the fact that, while it's perfectly okay to blow up people, if you blow up an animal by using it as the delivery system the animal rights people have a hissy fit and lobby Congress to... **** if I know what they want. But it works.
FYI, the bat thing ran something like this: During WWII the Army planned a sabotage system that basically involved releasing a lot of exploding bats over Japan- creating one hell of a lot of chaos and confusion, and propogating the explosions much more effectively than the normal gravity-based type of bomb does. The Army took over a cave full of some ten thousand Mexican freetailed bats, tied bombs to most of them, and put them on ice so they wouldn't get antsy or lost. After a while, the military decided to do a test drop, but the recently thawed bats weren't entirely de-hibernated yet, so some flew around and hit their targets, some just dropped straight down and died, and some got disoriented and flew to the local Army base, igniting a Jeep and a hangar.