Illustration acquired from the Public Health Image Library depicting a common housefly, Musca domestica. It is found all over the world.

Written by Daniel Pham

Houseflies were a health menace in the late 19th-century and early 20th-century for London’s urban population, but they were not considered scientifically as a potential vector for diseases until the turn of the 20th-century (Atkins 2012, 25). Prior to this discovery, there was a widely-held assumption that flies were not that impactful on human health because of their minuscule size. This post will introduce background information regarding how a swarm of these houseflies, “apparently harmless yet insidious insects,” became one of the predominant public health topics in London and other urban areas of the late 19th-century and early 20th-century, a time of rapid industrialization and urbanization (Wimbledon 1908). The sub-topics introduced on this page such as the environment that flies thrived in, flies’ relationship to livestock in the cities, and the public health response to flies can be found in other parts of the website, and they will provide a more thorough discussion respectively on those sub-topics.

A characteristic of late 19th-century urban areas was the enormous presence of manure and feces from both animals and humans, providing a breeding ground for houseflies (Atkins 2012, 42-43). In a time of rapid urbanization as a result of the Industrial Revolution, cities did not necessarily have the capacity or infrastructure to handle the changes that accompanied the influx of both animals and humans (Biehlar 2010, 70). Sewage treatment systems and clean water were often inadequately and ineffectively provided for the growing and dense population. As a result, many dwellers of condensed urban areas often had to rely on other methods to get rid of their wastes, with a majority of the residents dumping their feces onto the street (Paddington 1872). In addition, many cities were also home to numerous animals such as horses, cows, and pigs. These animals originally came with the people that migrated from rural areas to their new urban homes. It became apparent that the unsanitary conditions that the city dwellers had to live in attracted flies to breed in as well as an increase in the rate of infection (Bermondsey 1914). However, it wasn’t clear to the Medical Officers of Health what caused the disease, whether it was the living conditions or the houseflies (City of London 1892).

There was suspicion in the late 19th century that flies were vectors for some diseases, and that these diseases disproportionately affected children and infants (Morgan 2002, 101). However, it was unclear at the time why there was a particular correlation between diseases, houseflies, and minors. Some of the reports from the Medical Officers of Health suggest that because houseflies can affect the food supplies such as milk from cows, a popular item for children during this time period, children and infants were, therefore, more exposed to the flies than their parents (Deptford 1911). Another suggested that children had a weaker immune system compared to the parents whose immune system had strengthened over the years simply because they had lived longer and been more exposed to a wide variety of potential disease-causing vectors (Wimbledon 1913).

Houseflies thrived in particular environments and conditions. They preferred warmer conditions over colder ones, especially for laying eggs (Paddington 1908). One report mentioned that the most serious nuisance of hot weather was “the polluted air attracting the large numbers of blue-bottle flies.” Outside of the streets where horse manure predominated, certain buildings or portions of the cities were more problematic than others when dealing with the swarm. Flies had a major presence at pig deales. These sites were often dirty and unsanitary. In addition, the drainage of the liquids was inadequate and the scent was contaminated by “very large tanks of foul-smelling pig food.” These sites were often infected with swarms of flies, and these pests were largely not dealt with by the owners. Thus, the problem was largely ignored and worsened until there was external intervention by the Medical Officers of Health.

Eventually, in the 20th-century, efforts were made by the Medical Officers of Health to combat the diseases associated with the houseflies (Wimbledon 1904). A popular initiative was to eliminate or extinguish breeding grounds for houseflies to eliminate or reduce its population size. Proper sanitation and maintaining cleanliness of the “garden, yard, and area” were highly recommended by the Medical Officers of Health as a way to combat the spread of both the disease that the flies were supposedly spreading and the flies themselves (Willesden 1920). As a last resort, it was typical for the Medical Officers of Health to intervene and deal with the problem themselves (Wimbledon 1925).

Arguably, the nuisance and annoyance that people felt when dealing with these pests has not changed in the past century. However, people today do not have to necessarily worry about the potential diseases that houseflies may bring into their living spaces, and it is rare to see a sizable amount of the government’s resources be utilized to combat this insect. Regardless of the time period, however, there is one description that remains the same: its size certainly does not match its impact on society.

Medical Office of Health Reports

Secondary sources

Atkins, P. J. Animal cities: beastly urban histories. Farnham Surrey: Ashgate, 2012.

Biehlar, D.D. Flies, manure, and window screens: medical entomology and environmental reform in early twentieth-century US cities. Journal of Historical Geography 36 (2010): 68-78.

Morgan, N. Infant mortality, flies, and horses in later-nineteenth-century towns: a case study of Preston. Continuity and Change 17 (2002): 97-132.

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