"Purple Martins are aerial insectivores that do
most of their feeding at 100–200 feet above the ground. Their diet is almost 100
percent flying insects, and they opportunistically feed on flying ants, beetles,
butterflies, cicadas, damselflies, dragonflies, (drone) bees, flies, grasshoppers,
hoverflies, katydids, mayflies, midges, mosquitoes, moths, stinkbugs and wasps. Many
martin "landlords" mistakenly believe that Purple Martins devour large quantities of
mosquitoes. Actually, no scientific study has ever shown mosquitoes to comprise more
than 3 percent of the Purple Martin’s diet. Most mosquito species are simply not
available for Purple Martin consumption due to their nocturnal and low-flying
habits.
Though Purple Martins may be most numerous
around water, a nearby water source is not a prerequisite for having them. However,
Purple Martins will travel several miles to a water source to drink and bathe on the
wing. Water bodies are also used as feeding areas, because they generally have
higher densities and a greater diversity of flying insects than do most upland
habitats."
Purple Martin & Its Management in Texas, page 7
