Sorry to break you alls bubble, but Martins really don't eat much in the way of mosquitos. The favorite food source are dragon flies, but other insects as well.
In fact, they eat few mosquitos.
Article here
"Purple martins have an insectivorous diet, eating primarily flying insects such as moths, gnats, flies, and mosquitoes. They catch most of their prey in midair and they even drink in midair, flying over a pond, lake, or stream and scooping water into their bills while on the move.
Purple martins do most of their feeding between 160-500 feet high (50-150 meters). Because of this height, mosquitoes make up only a small portion of their diet, despite rumors that the birds can eat up to 2,000 mosquitoes per day. They could consume that many, but mosquitoes are not generally found at a purple martin's feeding height in such large numbers."