Why Do Mosquitoes Bite You? 6 Common Questions About Insects
Some questions about insects have crossed almost everyone's mind at some point, from the mosquito that only seems to bite you to the moth that endlessly circles a streetlight. We answer six of them based on what various scientific studies have found.
Why mosquitoes bite you and not someone else
The key is how your skin smells. Mosquitoes track their targets like a dog. From a distance, they follow the carbon dioxide you breathe out. Up close, they rely on heat and scent.
In 2022, Leslie Vosshall's lab at Rockefeller University in New York published the results of a study lasting about three years. Dengue mosquitoes were given a choice between nylon stockings that 64 volunteers had worn on their arms. The most attractive skin had higher levels of carboxylic acids. The favourite person drew roughly a hundred times more mosquitoes than the least popular one.
Those preferences held steady throughout the study. If you are the one mosquitoes go for, you will probably stay that way.
Do all mosquitoes bite?
No. Only females bite. Males feed on nectar, and their mouthparts are not designed to pierce skin.
Females also drink nectar, but they need the proteins in blood to produce eggs. Nectar gives them energy; blood provides the raw material for the next generation.
What's more, of the more than three thousand species described, only a small fraction seek out human blood. In the genus Toxorhynchites, not even the females bite. Their larvae eat the larvae of other mosquitoes.
Why it is so hard to swat a fly
There are two reasons. The first is their vision. The human eye blends about sixty images per second into continuous motion. The housefly's eye distinguishes around two hundred and fifty. To a fly, your swipe arrives in slow motion.
The second is how they take off. In 2008, Gwyneth Card and Michael Dickinson of the California Institute of Technology filmed flies with high-speed cameras. In a fraction of a second, the fly detects where the threat is coming from and repositions its legs to jump in the opposite direction.
Hence Dickinson's advice: don't aim at the fly, but slightly ahead of it, where it is going to take off.
Would cockroaches survive a nuclear bomb?
It depends on the distance. Close to the blast, the heat and shock wave would destroy them like any other animal. What is true is that they can tolerate far more radiation than humans.
In 2008, the show MythBusters put this to the test. At 1,000 rads, a lethal dose for a person, half of the cockroaches were still alive a month later. At 10,000, one in ten survived. At 100,000, none did. Some flour beetles even withstood the 100,000 rads.
The most widely accepted explanation lies in how their cells divide. Radiation mainly damages DNA that is in the process of being copied. Humans constantly renew their skin, gut and blood. Cockroaches divide their cells mostly when they moult.
Do bees die after stinging?
Only in one case: the honeybee worker. Its stinger is barbed, like a fish hook. In a mammal's elastic skin it gets caught, and as the bee flies off, it tears away the tip of its abdomen along with the venom sac. If it stings another insect, it can usually pull the stinger out and survive.
Bumblebees, solitary bees and the queen herself have smooth stingers or ones with tiny barbs. They can sting multiple times.
Nor is it true that a stinger must be scraped off and never pinched. A study published in The Lancet in 1996 found that the method makes little difference. What matters is speed, because the sac keeps pumping venom even without the bee.
Why moths circle around streetlights
For decades, the explanation was that moths navigate by the Moon and that a light bulb tricks them. In 2024, a team from Imperial College London and the University of Costa Rica made 3D recordings of moths and other insects near lamps. They found that the insects do not fly towards the light: they turn their backs to it.
For millions of years, the brightest thing around was in the sky. Keeping the light above their backs told them which way was up. With a bulb nearby, the moth tilts its back towards it, banks to one side and goes into orbit. If the light ends up below it, the moth flips upside down and plummets.
A moth circling a streetlight is not seeking the light. It is trying to work out where the ground is.
Frequently asked questions
Why do mosquitoes bite some people more than others?
Because of how their skin smells. A Rockefeller University study found that the most attractive skin had higher levels of carboxylic acids and that this preference remained consistent over time.
Do male mosquitoes bite?
No. Males feed on nectar and their mouthparts cannot pierce skin; only females bite, as they need blood to produce eggs.
How do you remove a bee stinger?
The method makes little difference, according to a study published in The Lancet in 1996. What matters is removing it quickly, because the sac keeps pumping venom.
Why are moths attracted to light?
They are not actually flying towards it: they try to keep it above their backs to tell which way is up. With a bulb nearby, they become disoriented and end up circling it.
Informative article written with the help of AI tools from the verified script of the video. The video is in Spanish.