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������CUriosity, experts across the CU �ֲ���ý campus answer questions about humans, our planet and the universe beyond.

Sammy Ramsey, your friendly neighborhood entomologist, explains why mosquitoes are irresistibly attracted to certain people.

Mosquitoes certainly have a type when it comes to choosing who to bite. But contrary to popular belief, it’s not sweet-tasting or Type O blood that attracts them.

“It's a weird situation involving your skin chemistry, how much you exhale and sometimes what you ate,” said Sammy Ramsey, an entomologist in the Department of Ecology and Evolutionary Biology and the BioFrontiers Institute.

To mosquitoes, every human is shrouded by an invisible chemical cloud made of a cocktail of skin oils, bacterial byproducts and other compounds. While humans typically can't smell the scents, certain chemical combinations make some people smell far more delicious than others to mosquitoes.��

Then, there’s the post-exercise banana and beer.��

Research shows people who exhale more carbon dioxide, like we do when we exercise, can attract mosquitoes from more than 30 feet away. And for reasons that are unclear, people who have recently consumed beer, bananas and cannabis are more attractive to these insects.��

found that beer drinkers at a music festival were 44% more attractive to mosquitoes than people who didn’t drink for at least 12 hours.��

Chemical camouflage

Getting bitten by mosquitoes is more than just an itchy nuisance. These insects are essentially flying hypodermic needles that can inject parasites and viruses into the human body, Ramsey said.��

“Out of all the organisms on the planet, mosquitoes have caused the greatest number of deaths, killing more than 600,000 people worldwide every year,” he added. “So protecting yourself by using effective repellents is very important.”��

Bug sprays containing DEET or picaridin, a chemical modeled after compounds found in black pepper, can act as a chemical camouflage, masking the body’s odors from mosquitoes. The key, Ramsey said, is to apply repellent evenly over exposed skin in a sweeping motion rather than spritzing it on like perfume.��

Catnip oil may also work as an alternative for those who are not a fan of DEET. The essential oil has been shown to be effective in preliminary tests in Uganda and caused no adverse reactions.��

“I guess the only concern with catnip oil is that cats would be obsessed with you and would get high from interacting with you, but I don't know if that's that big a deal,” Ramsey joked.��

Expanding territories

Here in Colorado, mosquitoes are generally less of an annoyance than in wetter parts of the country. The insects need standing bodies of water like puddles and ponds to reproduce.��

"But as rainfall and heat patterns change as a result of climate change, mosquitoes are becoming more numerous. We are seeing more of them in areas like Colorado,” he said.

This shifting pattern has led to an uptick in mosquito-borne illnesses in the United States. West Nile virus, typically a tropical disease, is spreading further north, for example. According to the Centers for Disease Control and Prevention, the United States has seen the reported at this point in the year since 2004, with cases popping up in states like Oregon. Another mosquito-borne illness, dengue, has surged by in the United States in recent years.

So whether you're the mosquito magnet in your friend group or the lucky one mosquitoes find stinky, it’s now the time to take them more seriously.

"As we shift the weather patterns of our world, we are going to see changes in the distribution of diseases," Ramsey said. "We have to make sure that we are doing everything we can to protect ourselves."