The insecticides used since the 1970s to control mosquitoes have become less effective. Researchers in India examined resistance mechanisms to α‑cypermethrin, a widely used insecticide. “Mosquitoes that survived exposure to the insecticide showed an increase in detoxifying enzyme activity,” Kumar said in a message exchange. “Mosquitoes have short life cycles and large populations, which allows beneficial traits to spread rapidly when the same insecticides are used repeatedly,” Kumar said. Its closest relatives, the common mosquitoes or Culex pipiens, overwinter in cold weather and prefer bird blood to human blood.