Green bottle flies are common insects found globally. These flies belong to the Calliphoridae family, also known as blow flies. While often seen as nuisances, their association with decaying organic matter raises questions about their potential risks to human and animal health. This article explores these concerns and how to mitigate associated dangers.
Identifying Green Bottle Flies
Green bottle flies are recognizable by their brilliant, metallic green or blue-green body. Some species may also display shades of copper, gold, or black. They typically measure 10 to 14 millimeters, slightly larger than a common house fly. Their wings are clear with light brown veins, and they have black legs and antennae.
Adult green bottle flies are active and produce a noticeable buzzing sound, especially indoors. They are often observed around decaying organic materials like carrion, feces, or garbage, where females lay eggs. Their presence in large numbers indoors can indicate a hidden source of decaying matter, such as a dead animal within walls or attics.
Health Concerns for Humans
Green bottle flies pose health concerns to humans primarily as vectors for disease transmission. As “filth feeders,” they frequent unsanitary environments like dead animals, feces, and garbage, picking up pathogenic bacteria. When these flies land on human food or kitchen surfaces, they can transfer these microorganisms. This can lead to food contamination with bacteria such as Salmonella and E. coli, potentially causing food poisoning, diarrhea, and gastrointestinal issues.
Green bottle flies can also cause myiasis in humans, an infestation of living animal tissue by fly larvae. This occurs when flies lay eggs in open wounds or on exposed flesh, especially in individuals with poor hygiene or pre-existing conditions. The larvae, or maggots, feed on the tissue, leading to discomfort, tissue damage, and secondary infections. While severe, myiasis is treatable with prompt diagnosis and removal of the larvae.
Risks to Animals and Livestock
Green bottle flies present a significant threat to animals, particularly livestock and pets, primarily through flystrike or myiasis. This painful, potentially fatal infestation occurs when flies lay eggs on an animal, and the hatching maggots feed on the host’s flesh. Sheep are especially susceptible, with larvae migrating through their wool to feed directly on the skin, causing massive lesions and secondary bacterial infections.
Flystrike can affect various animals, including rabbits, poultry, cats, and dogs, particularly those with open wounds, matted or soiled fur, or those unable to clean themselves. Symptoms include the animal stamping its feet, nibbling at its body, exhibiting lethargy, or having a strong, foul odor. If left untreated, flystrike can rapidly lead to toxic shock, severe infections, and death. Beyond direct infestation, green bottle flies can also carry pathogens affecting animal health.
Minimizing Exposure and Risk
Effective management of green bottle flies involves eliminating breeding sites and preventing access to vulnerable areas. Proper waste management is important, including keeping garbage cans tightly sealed and frequently emptying them. Prompt disposal of dead animals, which are preferred breeding grounds, can significantly reduce fly populations.
Maintaining cleanliness, especially around food preparation areas and pet spaces, helps deter flies. For homes, ensuring windows and doors have intact screens prevents flies from entering. For pets and livestock, regular health checks are important, with attention to cleaning dirty areas and promptly treating wounds. Shearing or crutching sheep to remove wool and dags also reduces their susceptibility to flystrike.