The role of light exposure on the final stages of development of Anopheles stephensi larvae to pupae and adult mosquitoes was explored. We demonstrated a significant reduction in the development of adult mosquitoes when larvae were bred in the absence of light compared with the control group bred in alternating 12 h of light and 12 h of dark. To correlate these findings at the molecular level, RNA levels of the visual arrestin gene were examined. Arrestins are an important gene family that play a role in the vectorial capacity of Anopheles and mediate neurotransmission as well as olfactory and visual sensory reception in insects. Semiquantitative polymerase chain reaction showed a reduction in the expression of the visual arrestin gene in pupae that developed from larvae in the absence of light compared with larvae bred under normal conditions.