Researchers from The London School of Hygiene and Tropical Medicine, UK wanted to know how effective DEET really is against mosquitoes. Most bugs are strongly repelled by DEET, and DEET remains a consumer favorite for outdoor summertime fun free of bugs. However, it is believed that DEET does not work quite as well on mosquitoes due to the mosquitoes unique olfactory system, which does not respond negatively to DEET. Therefore, a mosquito's immunity to DEET was explained by a mosquito's different genes. However, a recent study demonstrated that a mosquito's response to DEET has more to do with short-term changes and not permanent genetic differences. This recent article, published in PLOS ONE, reveals that mosquitoes become even less sensitive to the toxins in DEET after being exposed to the chemicals in DEET, similar to developing a tolerance to a drug. Three hours after exposure to DEET most of the mosquitoes pressed on looking for hosts. The researchers believe that mosquitoes have a unique ability to habituate to the smell of DEET, much like humans. Despite the resistance many mosquitoes have against DEET, the study's author insists that DEET is still an effective bug spray, and it can kill mosquitoes, but it may not work as well with mosquitoes as it does with every other bug. Have you ever sprayed a mosquito with DEET only to watch it fly away unharmed?   .