Green flies are common insects recognized by their distinct, shimmering coloration and characteristic buzzing sound. Often seen around homes, gardens, and outdoor spaces, their presence can prompt curiosity about their identity and habits. Understanding these insects involves exploring their physical traits, different types, life cycles, and ecological roles.
General Characteristics of Green Flies
Green flies typically exhibit a striking iridescent, metallic green coloration, which can sometimes appear with blue or copper tones. This vibrant hue results from structural coloration, where the physical structure of their exoskeleton reflects light in a specific way. They are generally similar in size to house flies, ranging from approximately 1/4 to 1/2 inch in length.
These insects possess transparent wings with light brown veins, black legs and antennae, and large, reddish compound eyes. As members of the order Diptera, or true flies, they are characterized by having only two functional wings, with the hind wings modified into small, club-shaped halteres that aid in balance during flight.
Common Types of Green Flies
The general term “green flies” often refers to a few specific types of insects, primarily certain blowflies and some hoverflies. Differentiating them helps understand their roles and behaviors.
Green Bottle Flies
Green Bottle Flies, often from the genus Lucilia, are the most commonly recognized green flies. The common green bottle fly, Lucilia sericata, is globally distributed and known for its metallic blue-green or golden coloration. These flies are somewhat larger than typical house flies, measuring about 10-14 mm. They are frequently found near decaying organic matter like carrion, garbage, or animal feces, where they lay their eggs. Their attraction to these materials is a key aspect of their ecological function as decomposers.
Hoverflies
Some Hoverflies, belonging to the family Syrphidae, can also display metallic green bodies. These flies are often mistaken for wasps or bees due to their mimicry, but they are harmless and do not sting. Unlike green bottle flies, hoverflies are seen hovering around flowers, feeding on nectar and pollen. Their presence is beneficial, as their larvae prey on garden pests like aphids, and adults contribute to pollination.
Other Green Insects
Other insects sometimes called “green flies” include certain aphids (Aphidoidea), which are small, pale green plant pests. Some horseflies, like Tabanus nigrovittatus (greenhead horsefly), also have green coloration. These are less commonly referred to as “green flies” and are distinctly different from the larger, metallic flies often observed buzzing around.
Life Cycle and Habits
Green flies, like the green bottle fly, undergo complete metamorphosis, a four-stage life cycle: egg, larval (maggot), pupal, and adult. The entire process can be relatively short, often completed within a few weeks, depending on temperature and food availability.
Female green bottle flies lay eggs in clusters, typically on decaying organic matter such as dead animals, garbage, or exposed meat. A single female can lay hundreds of eggs, sometimes up to 200. These small, white, oval-shaped eggs hatch into larvae, commonly known as maggots, within a day or two.
Maggots are pale, legless, and worm-like, immediately feeding on the decaying material. This feeding stage, important for their growth, lasts from a few days to a couple of weeks. Once fed, larvae move away to pupate, often burrowing into soil.
During the pupal stage, the maggot transforms into an adult fly inside a hardened, protective casing. After several days to two weeks, the adult fly emerges, ready to mate. Adults are attracted to moist environments and strong odors, guiding them to breeding and feeding sites.
Ecological Contributions and Concerns
Green flies, especially green bottle flies, play a dual role in ecosystems and human environments, offering benefits while also posing concerns.
Ecological Contributions
Their primary ecological contribution is as decomposers. These flies are among the first insects to arrive at carrion and other decaying organic matter, where their larvae consume tissues. This process helps break down organic waste, recycling nutrients back into the environment, which is an important part of the natural clean-up process.
The predictable life cycle of green bottle flies on decaying matter also makes them useful in forensic entomology. By analyzing maggot developmental stages on a deceased body, forensic scientists can estimate the post-mortem interval. Additionally, sterile maggots of Lucilia sericata are sometimes used in maggot debridement therapy to clean chronic wounds by consuming necrotic tissue.
Concerns
Despite their beneficial roles, green flies can be a source of concern. Their attraction to and breeding in decaying materials means they can become nuisance pests around homes, particularly near garbage bins or compost piles. They can enter homes through openings and contaminate surfaces and food. Because they frequent unsanitary environments, green flies can mechanically transmit pathogens to human food or surfaces. Proper waste management and sealing entry points are important for prevention.