I agree with CedarR about seeking a solution from a professional type,if you aren't sure.If the solution to put it down is the answer,then I think you should consider doing it humanely.If you are serious about a bat,or are too cheap to pay a vet or an animal shelter to put an unfortunate end to your pet,you shouldn't own any animal.You might not feel quite as satisfied as you think when you see the animal face an agonizing bloody death at the hands of someone it loves for doing something for which it DID NOT understand the consequences of.Do it humanely!