There are about 3,500 species of mosquitoes. Three of the genera that are primary vectors for deadly diseases are: Aedes genus mosquitoes that cause yellow fever, dengue fever, and filariasis; Anopheles genus mosquitoes that carry malaria; and mosquitoes in the Culex genus that are vectors for filariasis, avian malaria, West Nile Virus, Japanese encephalitis and St. Louis encephalitis. The diseases mosquitoes carry affect more than 700 million people a year.

These diseases are passed from victim to victim only by female mosquitoes. They have a special body part that juts out from their head. This proboscis is actually a sheath for two hollow tubes: one that injects saliva into the victim to keep its blood from coagulating and one that draws in the victim's blood. At the end of the tubes are two pairs of cutters that the mosquito uses to literally saw through the victim's skin.

The females need blood to nourish their eggs. They can lay 30-150 eggs every two to three days, so their need for blood is pretty exhaustive.

How Mosquitoes Work

Mosquitoes and Disease

After viewing these images, students will be able to visualize and describe the process of a mosquito biting a person.

• Function follows form As students experience this interactive, involve them in this discussion: Analyze the reasons that the Anopheles mosquito's proboscis is shaped the way it is. Look especially at width and depth. What other shapes might be useful in allowing her to take blood meals?
• Naming of the parts After students experience this interactive, involve them in this activity: Identify the location and purpose of the following parts of the mosquito body: antenna, maxillary palps, legs, wings, compound eyes, proboscis, abdomen, thorax, and head. You can access a diagram of the mosquito's anatomy here.
• Vectors After students experience this interactive, involve them in this activity: How is the disease delivery system of the Anopheles mosquito different from and the same as that of other vector insects, such as rat fleas, lice, and flies? (You can find a great background site on vector insects here.)