The deadliest animal on the planet is not a shark or a tiger. It is an insect whose name means little fly, and it kills over a million people every year. This episode takes apart the mosquito’s bite piece by piece. What looks like one needle is a bundle of six tools hidden in a flexible sheath: toothed blades that saw through skin with one thousandth of the force of a medical syringe, a probe that searches for a blood vessel, and a tiny syringe that pumps in saliva loaded with anticoagulants and compounds that quiet the immune system.

Finding you is just as sophisticated. Mosquitoes pick up exhaled carbon dioxide from over 30 feet away, then close in on body heat and the carboxylic acids produced by the bacteria on your skin, which is why some people get eaten alive while their neighbors go untouched. Only females bite, and only to gather protein and iron for eggs. The episode then asks the obvious question: if we could erase all 3,600 species tomorrow, should we?

• Mosquitoes have 72 types of odor receptors, and at least 27 are tuned to chemicals in human sweat. Garlic and sweet blood are myths.
• The malaria parasite changes its human host’s body odor, turning an infected person into a beacon for more mosquitoes.
• Both sexes live on nectar and pollinate plants, while their aquatic larvae feed fish, frogs, and dragonfly nymphs. In the Arctic a single caribou can lose up to 300 milliliters of blood a day to the swarms.
• Amber fossils show mosquitoes at work 99 million years ago, and possibly 125 million, well before the asteroid that ended the dinosaurs.
• CRISPR gene drives can now crash local populations within months, while engineers copy the mosquito’s cutting tools to design painless medical needles.