January 13, 2009 By C. CLAIBORNE RAY
Q. When you wake up with several mosquito bites and find one very bloated mosquito in the room, why has it bitten you so many times in a short period? A. A female mosquito takes a blood meal when it is carrying fertilized eggs, seeking a blood protein that allows the eggs to develop. Several reasons have been suggested for the multiple bites that many people (and animals) may experience from a single mosquito.
The simplest explanation is that the victim tossed and turned, interrupting the feeding before the mosquito had its fill. The mosquito has a sensory nerve that signals the brain when the midgut is full; otherwise feeding would continue until the bursting point. It is also possible that some blood types are not as easily thinned by the anticoagulant in the mosquito’s saliva, so the mosquito has to make more tries to get a satisfying meal. Another factor may be the mosquito’s search for an accessible vein near the skin surface, much like that of a nurse trying multiple sites to take a blood sample. Some studies suggest that multiple feeding attempts occur more often when the mosquito is either acquiring or transmitting a disease organism, like the malaria parasite, because of a chemical feedback system between mosquito and prey. It has even been suggested that some mosquitoes can transmit chemicals that make the host less sensitive to inflammation after a series of bites, so that more blood can be taken. Readers are invited to submit questions by mail to Question, Science Times, The New York Times, 620 Eighth Avenue, New York, N.Y. 10018-1405