Anopheles stephensi mosquito pupa. The pupa is the stage where a mosquito is developing between the larval and adult forms. The adult A. stephensi female is a vector for the disease malaria. Female mosquitoes feed on the blood of mammals, including humans, obtaining a blood meal to fuel egg production. Malaria is caused by the Plasmodium falciparum parasite, which is transmitted into the bloodstream by mosquito bites. Malaria is a disease presenting as severe cyclic fevers and can kill. Malaria affects millions of people in tropical and subtropical regions of the world.