Mosquito TRPA1 is a candidate thermo-sensing protein for host-seeking behavior. (A-L) AsTRPA1 (+) cells (green) are present along the whole proboscis and in association with sensory neurons (magenta: HRP-positive neuron, D and J). Note that some sensilla contain AsTRPA1 (+) signals (A, F, and H). All bars: 5 μm. (M-O) TRPA1-activating agent (AITC) disturbs the selected host-seeking behavior. Female mosquitoes were exposed to 1% (v/v) AITC at ZT16-19. Note that volatile AITC reduces the selected host-seeking behavior compared to controls (**p < 0.01, t-test; mean ± SD, n = 5).