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Filth Flies Management

Overview

True flies belong to the order Diptera that is characterized by having one pair of forewings. The hind wings are reduced to small, club-shaped structures called halters, which are used as balance organs. There have been about 120,000 known species of flies thorough the world. Interestingly, there are more than 16,000 species of flies found in North America. In this article, we intended to discuss a few species of flies commonly encountered in and around buildings, structures or yards. We called them filth flies because of their habits of breeding in filthy matter such as dropping, manure, garbage, cadavers, etc. Filth flies are considered pests not only because they are nuisance insects and can contaminate food, but also because they are disease vectors. They are capable of carrying and spreading a variety of health related pathogens to humans from filthy sources. Due to their high reproductive rate and short lifespan, filth flies can easily develop resistance to some commonly used pesticides. However, to adequately manage these tough pests, good sanitation practices, removal of the larval breeding sources, adult's habitats alternation, and exclusion/ pest proofing methods should be properly implemented along with the cautious use of pesticides. Pesticide applications should be used only as the last resort depending on the situation and as instructed in the product label.

Facts

  • House flies have a maximum flying speed of 5 miles per hour and can beat their wings 200 times per second.
  • House flies walk upside down using glue-oozing claw pads covered with hairs that exude a sticky fluid. That explains why they are able to walk up a smooth, polished windowpane or stroll around on a ceiling.
  • The name blow fly comes from an older English term for meat that had eggs laid on it, which was said to be fly blown.
  • Most flesh flies breed in carrion, dung, or decaying material, but a few species lay their eggs in the open wounds of mammals; hence their common name.

Identification

House fly

  • About 1/4'' in length
  • Dull gray in color
  • Four dark strips on the Thorax
  • Abdomen pale and fourth wing vein is angled
  • Has sponging mouthparts

Stable Fly

  • About 1/4 inch long
  • Look like house flies in size and color, except that they have a "checkerboard" appearance at the top of the abdomen and the stiletto-like proboscis, which are absent in adult house flies
  • Unlike other species of biting insects, both male and female stable flies can bite. They have piercing sucking mouthparts and feed on blood of warm-blooded animals, including humans

Flesh Fly

  • They are larger than house flies (about 3/8'' to 9/16'' in length)
  • Dull grayish- black in color
  • Have three dark stripes on the thorax
  • They have a checkerboard pattern at the top of their abdomen

Blow Fly

  • Adults are shiny with metallic coloring, often with blue, green, or black bodies.
  • Common blow fly species are:
    • The blue bottle fly- the head and thorax are dull gray and the abdomen is bright metallic blue with black markings. About 1/2'' in length
    • The green bottle fly - they have brilliant, metallic, blue-green or golden coloration with black markings. About 1/2'' in length
    • Bronze bottle fly- medium sized fly, 3⁄16-3⁄8 inches long, metallic green body with a bronze sheen and the forehead is silver, with a paired row of black spiracles
    • The black blow fly- they have a dark, olive-green body, black legs, and orange pubescence around the mesothoracic (The middle of the three divisions of the thorax of an insect) spiracles
  • They are scavengers. Females lay eggs on decaying meat, fish, garbage, fecal matter and dead animals

Black Dump Flies

  • About 1/4" long
  • They are black in color
  • Have a shiny thorax and abdomen
  • Larva feeds primarily on chicken and swine manure, dead animals, and rotting meat. They also feed on house fly larvae (a predator of house fly larvae)

Little/Leaser House Fly

  • Adults are approximately one-half to two-thirds the size of the house fly (about 3⁄16 inches long)
  • They are slender, and the median vein in the wing is straight
  • They have a brown-gray thorax with three black longitudinal stripes in the males. These stripes are not recognizable in the females
  • They have a mottled yellow abdomen
  • When the fly is at rest, wings overlap over the back of the body
  • Adults fly slowly in circles and tend to hover
  • Adults feed on a variety of liquids, while larvae breed and feed on decaying organic matter and excrement, especially chicken manure

Biology

Filth flies go through four developmental stages (complete metamorphose): eggs, larvae (maggots), pupa and adults. Mated females lay several batches of eggs (100 -150 eggs per batch) in decaying moist materials, garbage or animal manure. Eggs hatch in 24 hours.  Larvae feed and develop into a puparium (a rigid outer shell formed from the larval skin where the pupa develops). Adults emerge from the puparium in four to five days under favorite conditions (50- 60% RH and temperatures of 80-90°F). Newly emerged males and females mate, and the gravid females seek oviposition sites to repeat the life cycle again. The life cycle of filth flies depends on the fly species and environmental conditions such as moisture and temperature. Under optimal conditions, flies may develop from egg to adult as little as seven days, but in average, the developmental period usually takes between 21-25 days.

Habits

Depending on the species, the breeding habits of filth flies may include dead animal carcasses, decomposing meat and fish, garbage, or fecal materials (i.e., animal excrement). When food is available, 55-96% of adult house flies remain within one mile and 77-100% migrate within 2 miles of their larval breeding area. However, if food is scarce, house fly adults can travel up to 20 miles. During the daytime, house flies normally rest on the floor or less than 5 feet above the ground on the wall; while they change this behavior during the night, as they rest more than 5 feet in height. Though, they stay with a height of 5-15 feet when they rest.

Management

Non- chemical Management Methods

  • Keep indoor and outdoor areas clean
  • Eliminate outdoor adult's attraction areas such as, neglected or discarded materials, tall grass and piles of dead leaves, animal manure, and standing water
  • Regularly remove fallen fruits and filth build-up, especially in wet neglected areas.
  • Remove dead animals as soon as possible
  • Immediately clean any spilled food or liquid
  • Frequently pick up animal droppings
  • Store food in sealed containers
  • Install a proper ventilation system to keep the area dry and unattractive to files
  • Tightly screen windows, doors and openings of buildings
  • Keep trashcans and dumpsters clean, dry and tightly closed all the time
  • Keep dumpsters outside the building at least 75 feet away from outside doors, windows or other entrances
  • If there is so much trash that the lid cannot close, replace with a bigger container or schedule more frequent pickups
  • Install inverted cone traps OUTDOORS at some distance from building because of the smell.
  • Install sticky paper, tube or strip traps INDOORS in relatively SMALL areas
  • Mount Insect Light Traps (ILTs) INDOORS to monitor the fly population. This also will help in reducing the number of fly adults. Install the ILTs within the insect-flying pathway. Do not place ILTs too close to the doorways where the flying insect may not recognize them. It is known that ILTs are most effective when they are placed within 15 to 20 feet of every exterior door and not more than 5 feet above the floor. However, ILTs should NOT be within10 feet of any food preparation surfaces. ILTs should not be viewed from outside nor be placed too close to the windows where they compete with natural UV light.

Chemical Management Methods

Before treatment, a thorough inspection by the pest management professional (PMP) needs to be performed to determine the fly breeding, feeding and resting habits. In order to successfully manage filth fly problems, pesticide applications with approved EPA pesticides should be employed in conjunction with non-chemical fly management methods mentioned above. Chemical treatments for fly management include using ultra low volume (ULV)/ space treatments and residual pesticide applications along with baits.

ULV application of non-residual pesticides approved for fly treatment can be used as a space treatment ("fogging") to provide a quick knockdown of adult flies. Since no residual effects are associated with this type of treatment, ULV applications can only provide a temporary solution and cannot be used alone to eliminate the fly problem. Though, especially in rural areas where a heavy infestation of flies is abundant, ULV applications with special equipment can provide a provisional relief and reduce the fly pressure in indoor and outdoor areas. ULV applications should target fly resting places in barns, walls, bushes, trees, low vegetation, etc.

Although, residual pesticide applications can provide a longer pesticidal effect than non-residual pesticides, they are usually ineffective against larvae UNLESS they can penetrate the larval breeding habitat and contact the larvae. When using residual pesticides, pay particular attention to surfaces where filth fly commonly congregate or rest such as garages, dumpsters, refuse dumps, carports and storage sheds, building foundation, ornamental plants next to foundations, porches, the lower portions of trees, screens, window frames and sills, eaves, patios, doors, service line entrances, vents, roof overhangs, and other potential entry and resting areas. If necessary, indoor treatment should be carefully directed to fly resting areas, such as walls, ceilings, window screens areas, crack and crevices.

Fly baits are also available for outdoor and indoor fly management. Depending of the formulation, baits can be applied along the walls, windowsills or other places where flies generally congregate, breed and feed, including garbage collection areas.

Follow up applications of pesticides may be necessary in certain situations due to a number of reasons. For example, continuous infestations of flies from outdoor resources, environmental conditions that promote fly survival and reproduction, as well as, the sanitary conditions in the treated location. However, precautionary measures need to be taken before, during and after treatment. Remove pets, birds and food, pots, pans, and dishes; also cover fish aquariums before treatment. During the treatment, no people, food, or pets should be present in the area to be treated. If liquid pesticides are used, do not enter the treated area before the pesticide has dried completely. This may take between two to four hours depending of the pesticide being used, treated surfaces and environmental conditions. Adam's PMP will make sure to describe the precautionary measures to the customers and answer all related questions.

Frequently Asked Questions

Q: How to control flies in my house and yard?

A: A fly management starts before they become a problem. Implement a regular indoor and outdoor sanitation program, remove standing water, tall grass, fallen fruits, animal droppings, keep the garbage area clean, keep garbage can lids sealed tight and take the trash out regularly, apply proper building exclusion measures to prevent adult flies from gaining access to the building, use fly traps to capture and remove adults. When fly numbers are not tolerable, call Adam's for fly management. If you are experiencing a fly problem every year, it is advisable to have a fly management plan. This will provide you with a consistent fly management result and reduce the cost of repeated treatments and callbacks. Call Adam's Pest Control, Inc at 1.800.227.2214 for more details.

Q: What do flies eat?

A: Flies are scavengers; they eat what we eat and what we usually do not eat. Depending on species, sex and the life stage of a fly, they may feed on nectar, plant sap, garbage, blood, decaying organic matter, other insects, dead animal tissues, etc. However, regardless of their nuisance and health related problems, some fly species can be beneficial as pollinators, recyclers, parasitoids develop on or within insect pests.

Q: Where do fly go in winter?

A: Flies are short-living insects. An average life span of flies ranges from 1-3 weeks. Under optimal conditions (during summer), two or more generations may be produced per month. But however, before the onset of cold/harsh weather, a specific life stage of the last generation of flies hibernates; while, the rest of the life stages die in winter. Most flies usually hibernate or overwinter, in the pupa stage when the temperature drops below 47°F allowing them to make it through the winter. However, certain fly species, such as, cluster flies, face flies, blow flies, especially black blow flies, overwinter as adults in protected places such as homes, stables, etc.


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