[9] It is only when there is a sudden drop in temperature[9] that the cluster fly shifts to the interior of structures, holes in trees, loose bark, or other crevices and cavities.
[10][13][14] The change of genus to Pollenia (suggested by the pollen of flowers) occurred for Muscids having, among other features, the thorax covered with "down-like clothing".
[7][13] This species gained particular attention in the United States when Dr. W. H. Dall, of the Smithsonian Institution, published an article in the Proceedings of the U.S. National Museum for 1882.
[7][13] P. rudis may have been introduced to the United States upon slow sailing vessels in the cooler months of the year that traveled from Europe.
The species also could have been transported to North America in the ballast of ships containing soil and the cluster fly host, earthworms.
[21] In Europe, it takes 10–12 months for an egg to fully develop into an adult, resulting in one generation per year.
[21] P. rudis adults of European origin copulate in the autumn , leaving their first instar larvae in a dormant state in the bodies of earthworms over the winter.
[2] In North America, P. rudis eggs generally require 27–39 days to fully develop into an adult.
Cluster flies in North America overwinter in their adult stage, and copulation takes place in the spring.
[2] Female cluster flies preferentially oviposit eggs in humid areas with dense surface vegetation and high soil moisture.
Once the larvae hatch, they burrow into the soil by following natural pore spaces, such as holes near plant stems or paths that earthworms have already created.
[2] Adult cluster flies in North America are slow-flying insects that are active during warmer months.
[2] Cluster flies tend to enter homes and buildings in large masses in late summer or early autumn to seek shelter for the winter months.
Once cluster flies enter a home, they usually hibernate in inaccessible areas between walls and in ceilings until spring when they emerge and seek access to the outdoors.
[8] Piles of dead flies left in the walls can sometimes lead to secondary infestations of carpet or larder beetles and rodents.
In order to prevent cluster flies from entering a house, all exterior cracks and openings should be caulked or sealed.
[5] Once spring arrives the flies will try to leave on their own in order to lay eggs, but many times they enter other living areas of the home instead.
[23] Vacuum cleaners and aerosol insecticides may be used to control visible, sluggish flies, but professional extermination is the most reliable method for eliminating an infestation.
[12] Unlike the majority of blow flies in the family Calliphoridae, Pollenia rudis does not play a large role in the medico-criminal subfield of forensic entomology.
While most blow flies are attracted to rotting or decomposing matter, P. rudis is solely parasitic on earthworms and is unable to complete larval development on carrion.
However, the urban subfield of forensic entomology has been closely monitoring P. rudis because of its tendency to infest buildings and its status as a potential disease vector.
Urban entomology, which deals with the insects that affect humans and their immediate environment,[25] is responsible for investigating economic issues and civil proceedings involving arthropods.
[2] Due to cases like these, scientists have investigated the association of Pollenia rudis and its disease vector capability.
In 1973, a massive infestation of cluster flies in a German hospital triggered an investigation of the relationship between P. rudis and bacteria pathogen transmission.
[26] Careful examination of the flies revealed P. rudis is only capable of transmitting bacteria that causes opportunistic infections.
These results indicate that “mass infestations of cluster flies occurring in sensitive areas, especially in hospitals, may cause a low, but not neglectable health threat due to mechanical transmission of bacterial pathogens.”[26]