It rained for 40 days and 40 nights. Apparently when Noah and his family were loading the ark, someone let two mosquitoes aboard. Giving Noah the benefit of the doubt, and knowing the perseverance of mosquitoes, those two jerks were probably stowaways.
Coincidentally, we have seen an influx of these miniature vampires just in time for the Halloween season. Unfortunately, garlic and crosses do not scare mosquitoes. I know. I tried.