I have noticed a large increase in the number of insects and other unwanted creatures in my house. Without thinking I automatically squash and kill them. I'm not sure if swatting a fly is the same as cruelly hunting a deer for sport, but there is a small concern that I am destroying one of God's creatures.
My questions are: What is the purpose of these insects and small creatures? Even though I do this painlessly, am I permitted to kill them?
The Aish Rabbi Replies:
The great 16th century Kabbalist the Arizal stated that it is spiritually insensitive to kill even an ant for no reason.
However, let me ask you a question: Suppose you are a doctor, lying in bed at 3 a.m. and a mosquito is dive-bombing you so you can't sleep. You have an important surgery the next day, trying to save the life of a little girl. If you don’t get a good night's sleep, the likelihood of your being successful in the surgery is reduced. Can you kill the mosquito?
Of course! God made this world and everything in it for the benefit of mankind – both to use, and to protect. That's why it is permitted for us to eat cows – yet at the same time we have to protect species from extinction.
The bottom line: You can kill an animal if it serves a human purpose.
Of course, if it is just as easy to remove the insect from your house without killing it, that would be preferable. But if it will take time away from more important activities, then it is not worth it.