The poet Karl Shapiro began his poem “The Fly” with the line: “Oh hideous little bat, the size of snot.” It is not necessary to read further in the poem to get the idea that Shapiro is not a fan of flies. Shapiro, like most people, considers the fly to be a despicable organism.

Shapiro’s poem is about the house fly, an insect that has been a companion of unwilling humans from at least the beginning of recorded time and probably even longer. Even the scientific name of the housefly, Musca domestica, suggests a close association of the insect with humans.

To be sure, there are flies other than the house fly. Flies are classified in the scientific order Diptera, a word that literally means two wings, a characteristic of the order. There are over 15,000 named species of Diptera found in North America, so there are a lot of flies in the world. The most widely dispersed and the best known of all of these flies is the house fly.

Even though the house fly lives in close association with humans, it certainly has not been domesticated as its scientific name might suggest. Indeed, as Emerson suggested: “A fly is as untamable as a hyena.”

The house fly neither bites nor stings, so what is it about this insect that elicits such disdain among humans? The predominant reason would seem to be that the house fly can be called a filth fly. That term has been used to describe fly species that are associated with waste material, such as sewage and garbage, or with rotting plant material, animal manure and dead animals.

House flies hang around decaying stuff in order to deposit eggs on material that will be good food for their maggots. That in itself is not a bad thing. After all, fly maggots are part of nature’s recycling crew. However, house flies travel some distance from their breeding sites and that often results in conflict with humans.

Humans, you see, are not happy about sharing their abode with an insect that has been walking around on a dead animal or on raw sewage. Walking around on stuff is something that a house fly does almost as well as it flies. The reason for all of this walking around is that the house fly tastes with its feet. So when the fly stomps over our mashed potatoes and gravy it is searching for a meal.

Of course, most people have come to recognize that flies are not at all selective about the type of material on which they walk. That means that the house fly is capable of picking up disease organisms on its feet and transmitting them from one area to another. Consequently, the house fly has been shown to be able to carry germs that cause a number of human diseases, including typhoid, cholera, dysentery, tuberculosis, anthrax and infantile diarrhea.

As if being a vector of disease organisms is not bad enough, the house fly adds insult to injury by being a nuisance pest. It makes a nuisance of itself by flying around and crawling on people and things. But to most people, the most disgusting thing that the fly does is vomit on its food. The house fly has sponging mouthparts and has to predigest solid food before it can ingest it. So the insect spits digestive juices on potential food before sopping it up.
Having a fly spit in our food is insult enough but to be reminded that the insect might have been walking around on something like garbage, sewage or a dead animal before taking a hike on our food sort of seals the deal of why we hate house flies.
Consequently, we try to avoid contact with them.

Back in the Middle Ages, humans took note of the fact that some animals such as horses had built-in fly swatters. So we took hair from the tail of a horse, or used some suitable substitute material, attached it to a stick and called the device a fly whisk. We used fly whisks to keep flies from landing on our food. We developed swatters to inflict lethal physical damage to flies that would dare come within reach.

Readers with questions or comments for Tom Turpin may write to him in care of this publication.