Witnessing massive fly swarms is not necessarily unusual in the northeast region of the United States. Flies like black flies, greenheads, and fruit flies can be a nuisance to both urban and rural dwellers, but coastal areas tend to see the largest and most frequent biting fly swarms. In fact, dreaded fly swarms are so frequent on Cape Cod and Martha’s Vineyard that the price of luxurious homes on the island have decreased, as potential buyers sometimes get cold feet upon learning about the swarms that occur in the area. Homes often become infested with flies during swarming periods, and they can be surprisingly hard to eradicate. For example, during the winter of 2016, a long-running fly infestation took form in a Boston high school. Also, large-scale trapping systems have been established to control biting greenhead flies on the state’s coast, but with minimal success.

Chelsea High School in Boston closed for a few days so that officials could eradicate the massive fly infestation and conduct the proper repairs that may prevent future infestations of this magnitude. School officials also thoroughly cleaned the school with the hopes that the invading flies would move onto more suitably unsanitary conditions elsewhere. After using hidden cameras to surveil the invading flies within the school, officials came to the conclusion that numerous drain flies were accessing the school through pipes and drains. In order to repair the damaged pipes, workers had to lift a large concrete slab, which kept children out of school for days. In all, there were four faulty pipes, two of which were cracked, and the other two were broken. Flies could be seen congregating in large groups in just about every area of the school, including windowsills, bathrooms, hallways and everywhere in the cafeteria, even on the student’s food. The invading flies were fruit flies, drain flies, and probably several more species. Greenhead flies, which inflict painful bites, have been a source of misery for Massachusetts residents since the Colonial era, but residents of the state will likely never get used to them.

Have you ever sustained a bite from a fly?