Feeding processes and reproductive capacities of salivating and nonsalivating yellow fever mosquitoes, Aedes aegypti (L.), were compared. Salivation was shown to facilitate blood imbibement and possibly, but less clearly, skin penetration. The assumed presence of an anesthetic component in the saliva could not be substantiated. Egg production and egg hatching rates were not affected by the absence of salivation. Normal blood meal utilization appeared therefore to be present. It was conducted that the primary function of salivation lies in promoting the feeding process in this mosquito. Salivation thereby constitutes a definite survival value.