Genetically modified "gene drive" mosquitoes feed on warm cow's blood. Scientists hope these mosquitoes could help eradicate malaria.

Tony Nolan (left) of the Liverpool School of Tropical Medicine and Andrew Hammond of Imperial College London helped create the modified mosquitoes.

A technician begins the experiment by placing dishes containing dozens of modified mosquitoes in the pupal stage of development into large cages containing hundreds of their unmodified counterparts.