What if mosquitos suck out the bad blood?

Some mosquitos prefer to bite some people so I was wondering if they can actually smell if someone has more toxins in their body. I believe in Jesus and that everything He created was good but I really hate mosquitos so I’ve been thinking really hard why did he create mosquitos, I understand larvae because my pea puffers love eating them but mosquitos are so annoying and they especially love to suck my blood. I’m not the healthiest girl so maybe it’s helping me and I just don’t know it haha