When’s the best time to kill mosquitoes?

While they’re making love—at sunset.

No kidding.

This is just one of many fascinating discoveries being made at a place called Mosquito City. Located in the swamplands of central Tanzania, the “city” is home to the world’s largest captive colony of mosquitoes used for researching ways to combat malaria and other mosquito-borne diseases. Day and night scientists work to better understand mosquito behavior (like when and where they enjoy having sex) as well as cutting-edge approaches to trap, repel, and most importantly, kill them.

I first learned about Mosquito City during a trip to Africa several years ago when I met scientists from Ifakara Health Institute, a Tanzanian health research organization which runs the site. While I haven’t had the opportunity to visit, Fredros Okumu, Ifakara’s chief scientist, offered a behind-the-scenes look at some of the research underway there in this video. If you’re wondering how they get enough blood to feed all the mosquitoes, watch for the moment when Fredros puts his arm in a cage containing more than 500 very hungry mosquitoes for a feed! (For larger mosquito colonies, too big for one human to feed, a cow is on the mosquitoes’ dinner menu.)

Mosquito City is located in a region of Tanzania that’s hot, humid, and swampy. In other words—perfect conditions for its primary residents. Malaria has been so widespread in this part of the country—once infecting 80 percent of the population—that one meaning of the name of the local town, Ifakara, is, “the place people go to die.”

Fortunately, malaria deaths are on the decline in recent years. One reason is the use of insecticide-treated bed nets, which remain one of the most effective means to control the disease. (New bed net distribution efforts like the one that just launched in Benin are helping to ensure every person at risk of malaria is protected by one.)

Still, much more needs to be done to fight the disease, especially as mosquitoes become resistant to some of the pesticides used to control them. That’s why scientists at Mosquito City are working to better understand mosquito behaviors and find ways to outsmart them.

“It's kind of a love- hate relationship. If you can't beat them, you join them for now, but then you can kill them from the inside. And that's what we try to do here at the Mosquito City,” Fredros says.

Fredros and his team are studying one of the deadliest mosquito species, Anopheles funestus. In southeastern Tanzania, it is responsible for nearly 9 out of every 10 cases of malaria even though other species of mosquito are far more common. And yet, it is one of the least understood species of mosquitoes because it is difficult to raise in a lab environment. Our foundation is supporting the Ifakara Health Institute’s research into its behavior so they can mount a targeted campaign against them.

One promising approach may be killing them while they are mating. Ifakara scientists learned that mosquitoes, including Anopheles funestus, have favorite locations—like rice fields, trash heaps, and banana trees—to mate. The male mosquitoes appear at their favorite mating spots at sunset to begin a ritualistic flight dance, drawing in the females. Because these mating events occur at predictable times and locations, researchers are experimenting with regularly targeting these swarms with pesticides, dramatically reducing the mosquito populations and malaria transmission.

As the researchers dig deeper into the unique characteristics of different mosquito species, it’s become more important to be able to quickly identify them. Once they understand which species is posing the greatest threat, they can choose the best methods to eliminate them. But identifying mosquito species and other indicators, like age, can be a laborious process. At Mosquito City, scientists are working on some alternative identification approaches that would accelerate their research. One is to use their buzzing sound to identify them. Another option uses infrared spectroscopy. Mosquitoes have a unique electromagnetic signal. By crushing the abdomens of mosquitoes and analyzing them under a spectrometer, researchers can identify the species and age of the mosquito.

Many of the innovations coming out of Mosquito City are designed to meet the immediate needs of the local community, who work in small farming villages and spend most of their day outdoors. Researchers have developed a variety of mosquito traps, some mimicking the odor of sweaty feet, a smell that mosquitoes find irresistible. They’ve created a range of mosquito repellents too, including furniture treated with repellent that allows people to sit outside in the evening and stay protected. They’ve even developed a line of sandals which will keep mosquitoes at bay from the sweatiest feet, protecting their owner from bites.

What will the team at Mosquito City think of next? I can’t wait to find out.