Salivary glands are the ultimate site of development in the insect of mosquito born pathogens such as Plasmodium. Mosquito salivary glands also secrete components involved in anti-haemostatic activities and allergic reactions. We investigated the feasibility of RNAi as a tool for functional analysis of genes expressed in Anopheles gambiae salivary glands. We show that specific gene silencing in salivary glands requires the use of large amounts of dsRNA, condition that differs from those for efficient RNAi in other mosquito tissues. Using this protocol, we demonstrated the role of AgApy, which encodes an apyrase, in the probing behaviour of An. gambiae.