Any natural bug-killing sprays?

I have two cats in a small apartment, and I don't want to spray something toxic that they may lick up when I'm trying to eliminate flying insects. Personally, I use Pam cooking spray to down flies and other large bugs. The canola oil sticks their wings together, and the other ingredient must be doing something because they all die in less than a minute. However, I'm left with an oily wall or ceiling.