system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do bug bites create these weird bumps?
gpt
The bug generally injects you with something - anticoagulant so that it can get the blood out, numbing agent so that you don't feel the bite and slap it - different things.  Those things contain foreign proteins which trigger a histamine reaction exactly like hives, and that floods the area with extra fluid, making a hard bump.