We have two choices here, but one that is more likely, and that is termites. Back to them in a moment. The other possibility is ants, as most ants have "swarming" flights of winged males and females. These are fertile ants that leave their colonies for the mating flight, and following this event the males all die and the female ants lose their wings and begin new colonies.
However, far more dramatic will be the swarming flights of termites, and all kinds do this - drywoods, dampwoods, and subterranean. Where dampwood termites exist these are often amazing events, as they swarm shortly after the sun goes down and many or all of the colonies in an area will swarm at the same time. Hundreds of these large termites come out of every colony and take flight, and they are not strong fliers, so it is more of the appearance of hundreds of thousands of fluttering insects all around you. Subterranean termites do this as well, usually in late morning to early afternoon and often triggered by some rain event followed by sunshine. This combination of the proper temperature, water, and light intensity tell the termites that things are appropriate for their mating swarms to be successful and for the newly mated females to be able to find a new place to establish a colony.
Sometime shortly after they swarm from their parent colony all of these termites will lose all 4 wings, which quickly snap off at a weakened line near their thorax. They may even reach back and use their mandibles to remove a wing that seems to be stubborn, but once they are again safely within a cavity in the soil there would be no use for their wings and these long appendages would just be in the way. Again, here, the dramatic ones are the dampwood termites. Since they swarm when it is getting darker they often come to exterior lights around homes, and when many hundreds of them gather like this in one location the result may be a layer of thousands of their wings on the patio or deck or front porch.
The time of day when the swarming takes place can be indicative of the kind of termite - dampwoods and Formosans swarm in the evenings and come to lights. Other subterranean termites and drywoods swarm mid day. If the wings are found on the ground or patio outside then it does not necessarily indicate an infestation of the structure. But, if they are found on the inside, perhaps in window sills, there is a good chance they emerged from points inside the structure and the termites are infesting structural wood. A close look at the wings and the patterns of veins on them will easily distinguish termite wings from ants. And, another careful examination will distinguish the specific kind of termite based on the color, pattern of veins, and presence of hairs along the margin of the wing.
Mr. Pest Control
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