Mosquito pupa. Light micrograph of a pupa of the culex mosquito.The head bears two breathing tubes, used when the mosquito periodically comes to the water's surface to breathe. The abdomen, which has seven segments, ends in swimming paddles. The mosquito does not feed while in pupa form, because its mouthparts are changing from the larval to the adult form. After a few days an adult mosquito emerges from the pupal case. Culex mosquitoes inhabit urban or rural areas and usually bite in the evening or at night. They can transmit the diseases encephalitis and filariasis. Magnification: x10 when printed at 10 centimetres wide.