Nobody wants to do mosquitoes any favors. There are an estimated 110 trillion of the often-lethal pests worldwide, many of them spreading diseases including malaria, dengue, West Nile virus, chikungunya, yellow fever, and Zika. But according to a new study in the Journal of Experimental Biology , we may actually be training mosquitoes to bite us, thanks to a come-hither scent we’re emitting when we spray on DEET —an ostensible mosquito repellant that, in some cases, could actually be having the opposite effect. It was in 1946 that a U.S. Department of Agriculture chemist invented DEET— short for N,N-diethyl-meta-toluamide—an anti-mosquito formulation that was soon adopted by the military for use in jungle and other tropical settings. The chemical is believed to work in a number of ways— jamming smell detectors so that mosquitoes cannot recognize a human or animal target, conferring a bitter taste that mosquitoes detect on their feet, or mimicking the smell of natural mosquito-repelling plants.…