Tiny paper cups filled with water and floating mosquito larvae occupied space in Aseel Rawashdeh’s bedroom for months as she monitored the juvenile insects for changes in their behavior and structure. The 17-year-old high school senior from Texas was running an experiment: Would her inexpensive, eco-friendly concoction of baker’s yeast and essential oils kill the wiggling larvae?

By targeting mosquito larvae before they grow into pupae and then into flying adults, Rawashdeh wanted to prevent the transmission of mosquito-borne diseases at the root source.