Environment of Flies

Written by Diana Camacho and Elyse Buller

The common fly was spotted in numerous environments throughout the late 1800s and early 1900s. Individuals living in London encountered a great number of flies in everyday places. In 1862, The Metropolis Management Amendment Act offered a system for the removal of flies. However, only wealthy districts were helped by this act. The poorer areas of London did not benefit from this act. As time went on, the city of London became more proactive about removal of anything, including flies, that was believed to spread diseases (Velten, 43). In 1920, the Medical Officer of Health for Willesden summed up the fly problem as follows:

Flies breed in manure, ashbin refuse and decaying matter. A single fly lays about 500 eggs, which in hot weather will develop into full grown flies in two to three weeks. A great increase in the number of flies is noticeable in July, with a maximum in August and September. Flies carry filth from manure heaps and human excrement to foodstuffs, especially fish, meat and milk, in the pantry and shops. The contamination of food is a common cause of Summer Diarrhoea, a very fatal disease amongst young children. (Willesden 1920).

In what follows, we explore the environments this MOH identified as sites for fly proliferation and breeding: manure and garbage that included decaying foodstuffs. Both of these sites became even more congenial to flies in the heat of the summer.


George Shillibeer’s first London omnibus, 1829. Wikimedia Commons.

The number of flies began to increase as the numbers of horses on the streets of London increased. The streets were covered with piles of horse manure, which attracted flies. Ultimately, manure heaps became a tremendous public health issue. The individuals strolling through the streets of London quickly became alarmed by the number of flies seen around horses and their excrement. In 1911, the MOH for Deptford noted that, “As flies may be a source of dangerous contamination, owing to their frequenting places where filth exists, particular attention has been paid to stable refuse and manure heaps. ” In 1924, individuals residing in Hornsey experienced a cold and wet summer. The breeding of flies was evidently present due to it being their choice environment. This caused the Public Health Department to supervise areas where flies were most likely to breed, which included manure heaps and stables. (Hornsey 1924)

Several MOH reports cite manure heaps as major breeding grounds for flies. The MOH for Deptford pointed out that a single fly on a pile of manure had the ability to lay approximately 500 eggs. Usually, these eggs had the potential to develop into fully grown flies within three weeks if they were exposed to hot weather (Deptford 1911). The Bermondsey MOH claimed that flies lay eggs on manure heaps, or anywhere with a collection of moist refuse, and lay about 120 eggs per sitting and can result in several sittings over a small period of time. These eggs then turn into maggots that feed on the filth it lives in, in the presence of heat and moisture the maggot will turn into a fly in about 5 days to 9 days (Bermondsey 1914). Even before flies are developed, they are maggots, and could not exist but in the presence of filth (Hampstead 1914). Flies begin breeding in the months of June and July and continue breeding until October. The months of greatest activity are August and September, which is greatly influenced by the heat of those months. In breeding flies, the higher the temperature, the faster the development (Deptford 1913-67). In order to prevent the breeding of the flies, street and house refuse, as well as manure heaps, had to be removed once to twice a week at the least (Deptford 1913).

Garbage and food

Flies lived not just on manure in the streets and stables of London, but also in houses. Flies were lured closer to houses when there was manure, rubbish and decayed matter in and around backyards. If manure was left alone long enough, there was a chance for the flies to have a full life cycle outside of a house. However, when garbage and dust is tracked into houses from outside, this is an easy trail for flies to follow into a house and cause contamination to food and milk (Hampstead 1914). People were instructed to take precautions in regards to their home that consisted of cleanliness and protection of food supplies. The greatest attraction to flies was food; an important point in taking precautions was to cover all food when not being used (Deptford 1913). Flies inside houses were a common problem during summers.

L0076666 A baby sleeping with a fly on the teat of its milk bottle
A baby sleeping with a fly on the teat of its milk bottle; a man setting up an Aeroxon trap to catch flies. Colour lithograph, German, early 20th century. Wellcome Images.

As public health officials became more aware of the harm that flies were causing, they increasingly looked for prevention methods. Individuals became desperate for the elimination of flies; consequently, they quickly began to prevent a cozy environment by burning leftover food or placing it in a covered trash can. The waste of food was quickly becoming an issue due to the flies getting into any food source, but that was the only way to prevent flies from creating an unnecessary disease. This allowed a decrease in dirt; therefore, flies were beginning to decrease in number in certain areas of London, but this would not last long (Bermondsey 1914).

Flies invaded food in all types of environments. Because warm weather increases the growth of bacteria at a faster rate, it was understood that flies had more of an opportunity to contaminate milk before it even arrived to its destination (Deptford 1911). As a result, mothers began purchasing milk twice a day to prevent flies from entering and triggering lethal diarrhea (Fulham 1911). Breastfeeding also became a matter of importance when raising a child to ensure the child would be free of possible contamination in milk from flies, and gave the child a higher chance of growing to be healthy (Deptford 1911).

Thousands of flies also swarmed meat shops and slaughterhouses. Typically, the flies laid their eggs on the meat and instantly caused contamination (Lambeth 1925). There was such difficulty in preventing meat contamination because of the process in which meat was prepared for selling. There was free access for flies in the processes of trimming, boning, pressing and cooling the meat because these operations had to take place in a yard. In learning these breeding places and the proper precautionary actions, prevention became a community effort. Breeding spots of large volume were kept under observation with systematic and regular cleansing. All cleaning needed to be scrupulous.

Moreover, other small business owners did not escape the plagues of flies. Even manufacturers and builders were under scrutiny by public health officials so their efforts included clean sweeping the premises of any collections of waste material of an organic character at least once a week (Hackney 1912). All backyards should be properly paved and regularly swept, all manure should be removed daily, and cleanliness where food is prepared, eaten, or stored was the most important (Bermondsey 1914). Flies were an easy target of blame for disease outbreaks because of their ability to carry contamination and disease-causing pathogens from place to place. Flies were believed to be at fault for summer diarrhea, cholera, and typhoid, so these precautions quickly turned into essential disease prevention (Fasanella 1).

Eliminating flies

Complaints to and by the MOH regarding flies were common throughout the 20th century. Static water sites, derelict baths and tanks, ponds, and ditches were swarmed with flies and mosquitoes. People could not walk by anything without an encounter with a fly. Consequently, the Anti-Fly and Anti-Mosquito Campaign was initiated. The environments affected with the swarms of flies were inspected regularly and received treatment. A decrease in flies was accomplished by using a small quantity of Gammexane powder.

According to the MOH from Greenwich in 1961:

The treatment of house refuse in the dustbins was carried out by arrangement with the Borough Engineer, a small quantity of  ‘Gammexane’ powder being sprinkled into the dustbins at each weekly collection. Dust chutes in the numerous blocks of flats received regular treatment with ‘Gammexane’ powder by anti-fly personnel, as soon as possible after dust collection and 3.878 treatments were so carried out. (Greenwich 1961).

Flies and heat

Public health officials noted that tropical conditions were a great environment for flies to thrive in. For instance, barrack rooms were known for having flies multiply rapidly. Military men were often crowded into small barrack rooms, the majority of which were not ventilated, which caused an increase of fly reproduction. The sanitary conditions in barracks were strongly associated with disease and death. Evidently, a cooler barrack room meant that less flies would be available for further growth and breeding, but that was not always the case. However, a moist and unsanitary barrack room was always seen as a destination for a diverse of flies and illnesses (London County Council 1907).

Exposure to colder climates can slow down the breeding of flies. This particular climate has the ability to affect the rate at which they mature. These flies take refuge indoors throughout the winter time to avoid dying in harsh climates (Reis, 2). In 1907, Shoreditch experienced an extremely low mortality rate due to the absence of hot weather and low number of flies. The average death rate was relatively low since 1895. The environment they were living in only caused a mortality rate of 15.3 per 1,000 births in 1895, 40.3 for 1906, and 30.6 for 1905. Thereafter, mortality rates increased dramatically. (Shoreditch 1907)


There was a study done by Hafiz Azhar Ali Khan that discussed the relationship between temperature and the toxicity of the bacteria that the flies would carry. A fly’s body temperature changes with its surroundings, so the temperature can influence the toxicity of insecticides. Khan said that, “an insecticide with a positive coefficient becomes more toxic with an increase in temperature, whereas, those with a negative temperature coefficient become more toxic at lower temperatures” (Khan 2). Knowing this information can now help public health officials choosing insecticides depending on the season or month of the year (Khan 2). Respectively, Cristina Ferro analyzed diseases that are dominant in different habitats. Tropical rainforests are regions where flies can breed in large numbers due to the great amount of humidity. Females were observed with a great number of eggs while similar species were producing the same amount (Ferro, 2).

Primary Sources:

Deptford 1911

Willesden 1920

London County Council 1907

Bermondsey 1914

Fulham 1911

Lambeth 1925

Hampstead 1914

Shoreditch 1907

Hornsey 1924

Deptford 1913

Bermondsey 1914

Hackney 1912

Lambeth 1925

Secondary Sources:

Hafiz Azhar Ali Khan

Khan, Hafiz Azhar Ali, and Waseem Akram. 2014. “The Effect of Temperature on the Toxicity of Insecticides against Musca domestica L.: Implications for the Effective Management of Diarrhea.” Plos ONE 9, no. 4: 1-6. Academic Search Elite, EBSCOhost (accessed April 7, 2017).

Antonio Fasanella

Fasanella, Antonio, Silvia Scasciamacchia, Giuliano Garofolo, Annunziata Giangaspero, Elvira Tarsitano, and Rosanna Adone. 2010. “Evaluation of the House Fly Musca domestica as a Mechanical Vector for an Anthrax.” Plos ONE 5, no. 8: 1-5. Academic Search Elite, EBSCOhost(accessed April 7, 2017).

Ferro, Cristina, et al. “Spatial Distribution of Sand Fly Vectors and Eco-Epidemiology of Cutaneous Leishmaniasis Transmission in Colombia.” Plos ONE 10, no. 10 (October 2, 2015): 1-16.

Reis, Micael, et al. “Drosophila americana Diapausing Females Show Features Typical of Young Flies.” Plos ONE 10, no. 9 (September 23, 2015): 1-18. A

Velten, Hannah. Beastly London: A History of Animals in the City. Reaktion Books, 2013.