You may spend more time than you’d prefer shooing away house flies in your kitchen, which like to make their appearance apparent over most of the summer months, but there is another fly that you may notice making an appearance in early fall, the cluster fly.
The cluster Fly, which hails from the blow fly family (but has much better sanitary skills), is a little larger than a house fly (about 3/8 of an inch). Cluster flies are a dull gray and have golden hairs on the thorax, which gives them a sparkly sheen. When at rest, the cluster fly’s wings will overlap, whereas a house fly’s wings remain separate. Upon watching their habits, you’ll notice that they are much more sluggish than the typical house fly. Cluster flies are often called attic or window flies, as you can find them in those locations rather than flying around your kitchen.
FACT: Adult cluster flies are not attracted to garbage, feces or dead animals, but instead feed on flowers.
The process of life for the cluster fly is unique and has much to do with earthworms. Adults will leave their overwintering sites in the spring and will lay eggs in the soil where there are earthworms. The hatching larvae enter earthworms and finish the maturing process. With the onset of autumn, Cluster flies will seek secure overwintering sites. Preferred sites are secluded areas of homes and buildings, such as attics and wall voids.
During the autumn you’ll find cluster flies congregating on the sunny side of buildings and “clustering” in windows. They use scent to attract other flies; this sickly, sweet scent can even be smelled by humans. Cluster flies will not damage your home, but they can leave small stains on walls and curtains, especially when crushed. They do not hover and land on your food like the average house fly, and are not known to carry or transfer any diseases.
The best method to rid your home of cluster flies is to start with early prevention techniques.
Seal and caulk cracks and crevices around the foundation, windows and doors.
Make sure all screens around the home are secure and free of openings.
Contact a pest management professional if the problem warrants it.