Mosquitoes are important vectors that claim about a million lives every year worldwide by transmitting a range of diseases. As larvae, they occupy diverse habitats and are influenced by a suite of ecological factors that impact their adult life. Interestingly, the magnitude of these effects differs between males and females. Female mosquitoes show great plasticity of body size in response to environmental variability. Also, body size in females strongly correlates with their adult behavior and reproductive traits. Here, we varied levels of intraspecific competition to quantify how larval conditions impacted olfactory responses of adult females seeking hosts for blood. The preliminary results suggest that host-seeking preferences are strongly linked to variability in female body size. Analysis of the head transcriptome of large and small-sized females reveals differences in genes linked to the onset of host-seeking and olfactory sensitivity. Using these results, we are pursuing electrophysiological investigations to understand the neural bases of the observed size-dependent variability in mosquito host-seeking behavior. These results will be discussed in the context of mosquito population dynamics and the ensuing disease consequences.