- "It seems a harmless insect when you see it. But I have done some research. Mosquitoes transmit bacteria, viruses, and parasites. They carry the diseases encephalitis, yellow fever, and malaria. Malaria alone kills two million humans each year. Mosquitoes are the greatest mass murderers on planet Earth."
Mosquitoes are small, midge-like flies that constitute the family Culicidae, known as the deadliest animal family in the world due to their ability to transmit extremely harmful infections and arboviruses.
The mosquito morph was used in The Decision. After deciding to acquire and morph Hewlett Aldershot III, the second-in-command of the United States Secret Service, the Animorphs realize that they cannot acquire him in their true forms since Aldershot's hospital room is heavily guarded by human-Controllers. Cassie theorizes that they should be able to acquire his DNA in mosquito morph, since mosquitoes can suck blood. However, since only females suck blood and Cassie cannot tell the difference, all six Animorphs acquire the mosquitoes, on the chance that one of them ends up with a female morph. Their usage of the mosquito morph is what causes them to end up on an Andalite ship heading to Leera. After snapping back to Earth, Ax manages to awaken Aldershot from his coma while biting him in mosquito morph. Ax later uses the mosquito morph to sneak into a Yeerk base in The Pretender.
- The Forgotten (mentioned)
- The Decision (acquired and morphed by Jake, Rachel, Tobias, Cassie, Marco and Ax)
- The Threat (wild mosquito; eaten by Jake in dragonfly morph)
- The Pretender (morphed by Ax)
- The Reunion (mentioned)
- The Conspiracy (mentioned)
- The Journey (mentioned)
- The Unexpected (mentioned)
- The Return (mentioned)
- The Absolute