Mosquitoes might be the bane of a summer barbecue in Kendall or a stroll on Miami Beach, but researchers in Florida are now also looking at the insects’ more obscure targets—and how even a tiny, orange-flapped lizard could play a role in protecting our health.

While itchy bumps might make us feel like mosquitoes solely target humans, most of the world’s 3,600 mosquito species don’t specifically target humans, and the ones known in Florida bite humans, birds, amphibians, and reptiles like the brown anole, a pencil-sized lizard with a signature orange gullet.

Though these lizards are fast and feisty when they’re out hunting for insects, they rest on branches and leaves through the evenings and nights, making them an easy target for mosquitoes.

Brown anoles, said Melissa Miller, an invasion ecologist at the University of Florida, “may unwittingly be helping humans by absorbing the mosquito bites, and decreasing the transmission of serious pathogens to humans.”

The bad news for human health, Miller and her colleagues believe, is that the anole population is being squeezed out.

A couple of decades ago, reptile collectors inadvertently started a turf war by releasing Peter’s rock agamas they’d kept as pets into the wild.

No matter how much the male anoles spread their gullet, technically called a dewlap, to make themselves appear bigger and more
dangerous, the agamas—up to three times the size of the little anoles—were unimpressed. The agamas quickly spread, ate the anoles’ food and, sometimes, their little cousins themselves.

In many areas, the anole has disappeared, and the redheaded agama are now basking in the sun. While neither lizard is known to carry disease that mosquitoes can contract and then pass on to humans, the issue, Miller says, is the change in the mosquitoes’ diet.

Fewer lizards to feed on

In the early evening hours and throughout the night, mosquitoes can no longer feast on anoles, which typically sleep out in the open. Nor can they bite the agama, which hides in cracks and crevices as soon as the sun begins to set.

With less lizard blood on the menu, Miller and her colleagues theorized, mosquitoes could be biting birds more often. At least from a human-health point of view, that’s arguably the worst meal a mosquito could pick: Birds are some of the best hosts and multipliers of disease.

“And the more often they bite birds, the higher the chances that the mosquito picks up a pathogen” that they can then pass on to humans, Miller said.

To test their hypothesis, the UF team caught mosquitoes at three specific sites where the agama has taken over, then used DNA analysis to show which animals the insects had feasted on.

Next, Miller and her colleagues had to become experts at catching the agile reptiles with sticks, nets and even their bare hands. When the anoles returned to their original habitat, the team again caught mosquitoes. With the anoles back on the menu, the researchers believe that this second batch of mosquitoes would have drawn more blood from anoles, not from disease-riddled birds.

In theory, that would also mean that fewer mosquitoes carry viruses that could harm humans.

The researchers are still waiting for results, but in a few months, they’ll know exactly how the mosquito-bird-lizard-human transmission works. That, they hope, will add to our understanding of the unintended, often damaging consequences of human changes to the environment—like the introduction of non-native species like the agama, and the more notorious Burmese python, which has devastated the small mammal populations in the Everglades.

That the large-scale burning of fossil fuels has warmed the planet by 2 degrees Fahrenheit, on average, is another factor. Whether any of the mosquito-borne diseases become endemic in Florida isn’t just tied to the anoles, of course, but “will depend on global warming, and whether we start seeing more and more mosquitoes that stay year-round,” said Dr. Joyti Somani, an infectious disease specialist who used to treat malaria, dengue and other mosquito-transmitted diseases in Singapore before joining Miami-Dade’s Jackson Memorial Hospital last year.

At Miami-Dade’s Mosquito Control, division chief Dr. John-Paul Mutebi also said he worries that a warmer climate enables some mosquito species to spread to regions that were previously too cold, and that the season they’re most active is getting longer. Within the next 25 years, researchers project that the US mosquito season will last two months longer than today.

“That is really, really dangerous, because towards the end of the transmission period, that is when most of these mosquitoes are infected,” Dr. Mutebi told the Herald. “They keep on picking up the pathogens as the season goes,” he said.

Dengue, Chikungunya, Zika, and West Nile virus are among the diseases Dr. Mutebi lists as worrisome, as is eastern equine encephalitis. Also known as Triple E, the virus swells the brain and kills about one in three patients.

“If you don’t die from it, you’re going to end up with some long-lasting effects,” Dr. Mutebi said, including permanent blindness, loss of hearing, or other physical and mental impairments.

Right now, the odds of contracting Triple E are almost trivially low. In 2023, Florida reported only two cases in humans. But contracting any mosquito-transmitted disease is a numbers game.

The more mosquitoes there are, the longer they stay active, and which species they bite all matters. With Florida under attack by invasive species, from Burmese python to lionfish, the UF researchers hope that their results could help authorities direct resources to fighting the agama—and protecting the anoles.

“Brown anoles seem like such a small component of the ecosystem,” Miller said, “but even removing that can have impacts that are felt much higher up the food chain, all the way to humans.”