Can you tell which of these mosquitoes is Aedes aegypti and which is Aedes albopictus? Even for professional entomologists, visually identifying wild-caught mosquitoes to species requires rearing them to either fourth instar larvae or adults. A new set of improvements to a DNA-testing method developed by the CDC, however, will enable faster identification of either (or both) species’ presence in a collected sample of first instar larvae. And, to answer the question, that’s Ae. albopictus on the left and Ae. aegypti on the right. (Photo credits: James Gathany, CDC Public Health Image Library)