Although they are often connected with inadequate hygiene in a certainly area, cluster flies tend not to carry around diseases and thus do not symbolize a risk to humans especially since they will not lay their eggs within the food of people.

Instead they much like to turn their attention earth worms instead and look to put their eggs near to the burrows of earth worms. They will either make this happen in soil or on leaves that have been aging.

Any time their eggs have finally hatched the cluster flies larvae will look to locate earthworms and often will expect to feed on them acquiring their nutrients through the body of the earth worm. This may cause significant amounts of injury to the earthworm and definately will ultimately kill them.

Once the Cluster flies larvae have evolved to a fully developed adult, they will likely abandon the earth worm as they are now fully capable of supporting themselves.

Nonetheless while they will likely not trigger any real inconvenience to humans they are able to nevertheless be a great pain to us should they are actually in our environment.

Cluster flies are usually outdoor flies however when the weather becomes cooler, in late autumn and winter for instance, they will often decide to move inside, sometimes in their thousands, and will be discovered hibernating in buildings or attics, thus the reason they are usually called "attic flies". They prefer inaccessible places such as within the walls, inside cracks and cavities close to the ceiling or around windows, or in basements, lofts as well as other rooms that are not used very often. Once the weather warms a bit, they may start flying around and those who have ever suffered an attack of cluster flies can help you understand isn't a pleasant experience.

Properties and buildings which might be in the country could be more at risk of bringing in cluster flies due to the actuality that you have fewer places for the adult flies to discover shelter. You are also very likely to find cluster flies in structures which are situated near to where earthworms can be found, for instance areas of turf or grass, gardens.

Cluster flies look much like the normal housefly although they are a bit bigger in dimensions and will be identified by bodily markings including the yellowy golden coloured hairs on the thorax and by the different tones of grey throughout the abdomen. Additionally they move more lethargically than the common housefly.