Different species of mosquito have different ranges. To get a sense of
the "ballpark figures," the American Mosquito Control Association's
website gives some examples:
A type of mosquito described as a "weak flier" is said to be "known to
fly up to 2 miles" from their breeding source.
A different type of mosquito called a "strong flier" is said to be
"known to fly many miles from their breeding sources."
And a good summary of the situation is given as:
"Most mosquitoes stay within a mile or two of their source. However,
some have been recorded as far as 75 miles from their breeding
Information given on the "Joint Statement on Mosquito Control in the
United States" page at the Environmental Protection Agency's site
supports this general range, and also says:
"The underlying philosophy of mosquito control is based on the fact
that the greatest control impact on mosquito populations will occur
when they are concentrated, immobile and accessible. This emphasis
focuses on habitat management and controlling the immature stages
before the mosquitoes emerge as adults. This policy reduces the need
for widespread pesticide application in urban areas."
Meaning that the preferred method is to hit the breeding grounds
rather than try to deal with the adult mosquitoes. However,
"Both agencies" [EPA and CDC] "recognize a legitimate and compelling
need for the prudent use of space sprays, under certain circumstances,
to control adult mosquitoes. This is especially true during periods of
mosquito-borne disease transmission or when source reduction and
larval control have failed or are not feasible."
So they also concede that there are circumstances for spraying a more
general area in an attempt to control the adult mosquitoes.
Google searches used:
mosquito life cycle
mosquito miles breeding source
American Mosquito Control Association
EPA Joint Statement on Mosquito Control