What Happens Inside of a Mosquito Bite
A mosquito bite is much more sophisticated than a needle prick. The mouthparts that penetrate the skin are surrounded by the labium (lb), which folds and stays outside, the maxillae help make the puncture, the labrum is the tube that sucks up the blood, and the hypopharynx sends saliva down. Once inside the skin, the labrum bends and probes until it finds a capillary (which can take up to two minutes).
Once the capillary is pierced, the mosquito sucks hard—sometimes hard enough to rupture the capillary. The saliva contains anticoagulants, which keeps the blood flowing during the 4-minute-long feeding, and whatever parasites the mosquito was carrying. This video shows the biting process in all its gory details.
The ice cubes are skin cells, the bendable hook is the mosquito straw, the red lines are the capillaries (you can almost see red blood cells). The images were captured by Valerie Choumet and her colleagues at the Pasteur Institute in Paris by using a microscope to look through a flap of mouse skin. Check out the supplementary section for awesome pictures and videos.
I could talk about mosquito bites all day. Here are a couple of other awesome articles.