Can't die from bug killers
"The more a pesticide is used, the greater the chance that the insects targeted will develop immunity to the chemical. Pesticide resistance is not only very common, but it also usually happens rather quickly. Sometimes all it takes is a single generation. Imagine that a group of insects survives the pesticide and is able to reproduce. More likely than not, the offspring will be resistant to the pesticide from birth. Those that are not immune will die, while the strongest will survive. Since many insects reproduce quickly, several generations can be born within months or even weeks. By the time a few generations have passed, all insects are likely to be resistant to the pesticide."
Bugs are not able to become pestcide resistant alone
"Bugs pick up pesticide resistance from pesticide-eating bacteria"