Based on environmental conditions, flying insects could be one of several insects:

• Swarming ants or termites - both have mating swarms where numerous reproductive insects leave the original nest to mate and then find a new nest.
• House fly, fruit fly or fungus gnats. For flies, it is very important to find the source of infestation. Until you get rid of the breeding site, the adult flies you see in your home will continue to be a problem.