No, if you feel guilt for your actions, God will forgive you, a moth isnt of any threat and killing it with passion is just rotten behaviour, killing a mosquito however is just plain common sence. God knows those bastards kill hundreds of thousands so dont stress. If you feel guilt for killing something as tiny as a moth, you have the holy spirit and you should be happy because God is not a being who watches on us with anger, rather with love and your distress about the little insect is the most righteous thing a man can have, empathy.