The surprising beauty of mosquitos | Felix Hol

Felix Hol says mosquitoes are beautiful under magnification: their eyes have intricate facets, and their mouthparts are covered in scales and hairs. For him, close attention to their appearance is also a way to understand how they work. Of roughly 3,500 mosquito species, around 90 feed on humans, so the familiar human-biting mosquito is only a small part of the group.

Mosquitoes locate people through a sequence of cues. They can detect exhaled carbon dioxide from tens of meters away, then rely more on body odors, heat and visual signals as they get closer. After landing, receptors on their feet let them taste the skin. Some can take a blood meal in just 20 to 30 seconds, making their rapid feeding part of the challenge of preventing bites.

Mosquito-borne diseases kill about 500,000 people a year, a toll that has risen in recent years. Bed nets have helped reduce malaria cases over recent decades, but mosquitoes appear to be shifting their biting toward earlier evenings or later mornings. Hol says it remains unclear how that shift occurs and what else is driving it, so the change should not be treated as having a single established cause.

Mosquitoes can also adapt around control measures, including by developing insecticide resistance. Preliminary data suggest that some mosquitoes surviving insecticide exposure become hyperactive, but Hol says researchers do not yet know whether that means they bite more people. His broader point is that control should combine approaches: relying heavily on insecticides risks losing effectiveness as mosquitoes adapt.

Hol’s lab studies biting with a “bitoscope,” which uses artificial skin and an artificial blood meal to record bites at high resolution, and BuzzWatch, which measures mosquito activity over a 24-hour cycle. The team shares open-source code and builds affordable tools for other researchers. Its fieldwork in Uganda and Kenya complements laboratory studies of standardized, lab-raised mosquitoes, helping test how observations hold up under local conditions.

In Uganda, the team found that two malaria-transmitting species responded differently to daytime conditions: one stayed inactive while the other remained responsive. Hol says the responsive species could become more important for malaria transmission as bed-net use increases. Research into when mosquitoes bite, and the genetic mechanisms behind those patterns, could therefore help guide vector-control choices, though the findings do not establish that one species will necessarily drive future transmission.

Climate change and human movement, including shipping, can help mosquitoes reach new places. Warming or increased rainfall may make some areas suitable for species that could not previously thrive there, but the effects differ by region and the pace of mosquito adaptation is unknown. Local conditions and strained healthcare systems also shape disease transmission. Hol’s account points to the need for research and collaboration, as well as control tools that can reach the people most affected.