In what they call surprise findings, Johns Hopkins Medicine scientists report that -- unlike fruit flies -- mosquitoes' odor sensing nerve cells shut down when those cells are forced to produce odor-related proteins, or receptors, on the surface of the cell. This "expression" process apparently makes the bugs able to ignore common insect repellents.

In contrast, when odor sensors in fruit flies are forced to express odor receptors, it prompts flight from some smelly situations.

— Read more in Surprise findings suggest mosquito odor sensors are sensitive to molecular regulation to avoid insect repellents at Science Daily.