What does Buddhism say about intentionally killing dangerous insects and beings?

Recently I got into a long debate with some people on Reddit about killing pestilent, poisonous insects. Feel free to read it . There are some interesting scientific findings. Whatever the word is for people who go over-board with their compassion/ahimsa trip... I think they are doing that, considering it was a poisonous spider (about to give birth to 100 more) I dispatched. **So what does Buddhism say about *intentionally* killing dangerous (poisonous) and/or pestilent insects?** Specifically dangerous insects in one's personal and community environment. Surely, the suttas, aimed towards forest-dwellers, must have some guidelines on harmful insects and animals.