Flies: “Shoo fly, don’t bother me!” There are over 16,000 species of flies in North America alone, and this insect plagues every part of the world (except polar ice caps). Besides being a nuisance pest, flies have been linked to the spread of over 100 pathogens, including: typhoid, cholera, dysentery, salmonella, anthrax and tuberculosis. Each time a fly lands, it is capable of spreading thousands of bacteria. The U.S. Department of Agriculture has also reported that flies are responsible for the contamination or destruction of over $10 billion of agricultural products annually. Below are the most common regional flies, their defining characteristics, as well as control strategies.
House Flies are typically gray in color, with four black stripes on their thorax, and range in size from 4mm-7.5 mm. This species consumes a wide variety of food, ranging from human food to animal carcasses to excrement. House flies are prolific breeders– one pair of flies can produce more than one million offspring through their offspring’s offspring in a matter of weeks. Their life span ranges from 15-30 days on average. House flies are covered with tiny hairs that serve as their taste organs, and their compound eyes (which encompass thousands of individual lenses) affords these flies a wide field of vision. House flies are the most common of all domestic flies, and their infestations account for approximately 91% of all flies in human habitations.
Fruit Flies are easily distinguishable from house flies in that they are significantly smaller (3-4mm), and are commonly found circling overripe or rotting fruits and vegetables. Fruit flies have characteristically red eyes, with bodies ranging in color from tan to dark brown. While fruit flies can be a problem year-round, they are more common in late summer and early fall due to the presence of organic substances. A fruit fly’s life span, from laying of egg to death, is between 40-50 days under ideal circumstances. The best way to avoid problems with fruit flies is to eliminate their source of attraction.
Phorid Flies, also known as “humpbacked flies,” are extraordinarily small (measuring only 0.5-5.5mm). While most are black or dull brown in color, there are some varieties that have a yellowish hue. Phorid flies have a short and erratic flight pattern, and a peculiar habit of running across TV screens and windows. These flies are found all over the world, but prefer warm, tropical regions. Phorid flies favor decaying, moist, organic material as a source of food and primary site for laying eggs. Their entire life span is approximately 45 days.
Fungus Gnats are small (approximately 3mm), delicate, mosquito-like insects that develop in the soil of houseplants. Larvae of fungus gnats are typically located in the first 2-3 inches of medium, and feed on algae and plant roots; adult fungus gnats don’t feed. Though their lifespan is extremely short (7-10 days), female fungus gnats may lay up to 200 eggs. In general, this pest can be controlled by allowing soil/growing medium to dry between watering. While fungus gnats are non-biting insects, they are certainly a nuisance pest. Geraniums, African violets, and carnations are especially prone to fungus gnat infestations, with signs of such including: yellowing, wilting, and poor growth.
Ensuring that your home or business is clean is the first and most important step in fly control. Taking out garbage regularly, disposing of organic items that have been sitting out for an extended time frame, and cleaning with a disinfectant are all strategies that can greatly assist in these efforts. Eliminating moisture (such as leaky drains and liquid trash residue) and food sources are also highly effective in eradicating flies. Chemical strategies may include, but are not limited to the application/use of instant aerosol insecticide, residual spray, and enzymatic cleaner.