Fly Infestations

This article contains comprehensive instructions for getting rid of a pesky fly infestation in your house.

Here an outline of the topics covered:

Why Are Flies in My House?

The flies want food. Each type of fly tends to have distinct feeding habit and favorite sources of sustenance.

The common house fly is known to feed on human food, garbage, and excrement, whereas fruit flies and drain flies typically feed on fermenting liquids and bacteria found throughout homes. Finally, blowflies and cluster flies mostly eat carrion.

Some of the most common fly food sources include fruit juice, soda, and beer. The pests are also capable of turning solid foods into liquid with the enzymes found in their saliva.

Since they defecate where they eat, flies regularly contaminate the food they consume. Additionally, they tend to lay their eggs in established food sources, which allows larvae to eat as soon as they hatch. Also called maggots, larvae will feed on detritus, dead animals, fungi, plants, and decaying produce.

How Did Flies Get Inside My House?

Points of Entry

Flies are generally associated with filth and can enter homes in a number of ways such as through torn screens and gaps in windows and doors. They are typically drawn to private properties by the promise of consistent food.

Since fecal matter is a main food source, flies are drawn to homes with pets. Moist, damp foods found decomposing in the trash are also major attractants. House flies prefer dark, damp areas for reproduction, so basements and bathrooms with leaky pipes draw the pests inside.

Fruit flies are attracted to overripe fruits, alcohol, and sugary drinks Some species of flies lay their eggs in produce that is starting to ferment, so homeowners might bring flies into the home unknowingly after a trip to the grocery store. Finally, other species enter residencies through drain and sewer pipes.

Growing Populations

Once inside, flies multiply quickly. In some species, one generation can produce up to 30,000 flies at a single breeding space. The pests like to breed in garbage receptacles, produce, on raw meats, and around sink and bath drains. Given their prolific breeding habits, getting rid of flies once they’re inside the home is a monumental task.

What Problems Can They Cause?

Fly infestations often cause illness, as the pests carry over 350 types of bacteria at any given time. In addition to mild stomach cramps, these pathogens can cause some serious diseases, including:

  • Salmonellosis – Symptoms include fever, diarrhea, and vomiting.
  • E. coli Infection – May lead to kidney failure in severe cases.
  • Shigellosis – Infection that can result in gastric distress and fever.

4 Steps to Get Rid of Fly Infestations

Step 1: Sanitize

The first step to getting rid of flies is to identify where the larval breeding is taking place.  The breeding sites must be eliminated or sanitized depending on the spot.

The number one indoor fly deterrent for all species is sanitation. Keeping a home clean, free of garbage, and in good repair goes a long way toward creating a habitat that is unfit for flies.

Start by following this sanitation checklist

  1. Check all windows and screens for gaps, tears or holes
  2. Check drains or garbage disposals for leaks or the accumulation of food waste beneath sinks or within floors.  Leaking drains can be a magnet for various fly species. Be sure to eliminate any food residue that has gathered beneath sinks, on floors, or in crawl spaces etc.
  3. Use an industrial drain cleaner to unclog or clean drains
  4. Separate food waste from other garbage as much as possible. Drain liquid from any food waste containers and keep them dry as possible.  Seal food waste before disposing.
  5. Seal containers (milk, yogurt etc) in bags before disposal
  6. Recycling – make sure all empty cans, bottles, plastic etc before disposing
  7. Try placing external garbage cans down wind of windows and doors if possible
  8. Check for any animal waste or dead animals around the home
  9. Make sure all garbage cans have lids, both inside and outside
  10. Make sure all garbage is disposed in plastic bags, not directly in the can

Step 2: Traps

You can capture adult flies using attractant fly traps or adhesive fly tape. Traps serve as visual tools for monitoring the success of your efforts.  They also offer decent control in small spaces with low fly populations. Check the traps regularly and replace when damaged. When using sticky traps, be sure to place them in locations where people are unlikely to accidentally touch them.

Fly traps are available in many different styles. Here are some effective traps, with good reviews on Amazon.

BugMD Window Fly Trap
156 Reviews
BugMD Window Fly Trap

  • Discrete trap fits in window corner
  • Sticky glue captures bugs
  • Unique design

UV Light Trap

  • Flying bugs attracted to the light
  • Sticky glue captures flies
  • Just plug it in

Trappify Fly Sticks
4,215 Reviews
Trappify Fly Sticks

  • Hang it anywhere
  • Works inside or outside
  • Kills anything that flies

Sale
DynaTrap

  • Plug it in
  • UV light lures flies
  • Built in fan sucks them in

DIY Traps

There is nothing wrong with trying some of the well known DIY solutions out there, but understand that they may have some limitations.

Vinegar Traps
A vinegar trap has a simple design consisting of a container filled with an attractive bait and hole-punched plastic wrap that covers the opening. The trap works by drawing flies in with the bait and allowing them to climb inside through the holes in the plastic. Once inside, the flies cannot escape, as they are not skilled enough fliers to exit through the small holes.

Vinegar, as the name of the trap may indicate, is often the bait used because it is cheap and can effectively attract fruit flies. Individuals may also use baits like slices of fruit, balsamic vinegar, or wine, which have similar attracting powers on fruit flies. Many hardware stores and online retailers sell manufactured versions of this trap, as well.

Overall, each version of the vinegar trap has the same effect on controlling a fly population, which is a rather minimal one. Though capable of catching a few flies, a vinegar trap cannot eliminate a fruit fly infestation.

At best, a trap can be used to monitor the severity of a fruit fly problem. Vinegar traps are also unsightly. Seeing a container filled with dead flies in the kitchen is enough to make anyone lose their appetite.

Fly Strips
A long strip that is sticky on both sides, a fly strip can be made at home or purchased. Meant to hang down from a high point in the kitchen, a fly strip catches any flies that land on it.

Most fly strips do not have a bait to draw fruit flies in and simply catch flies that happen to fly onto the trap. Like the vinegar trap, this method cannot take care of a fly population and will only indicate the presence of flies in the home. Also like vinegar traps, fly strips look unappealing, and guests that see them may assume the home is unsanitary.

Rue
Rue is an herb that some individuals believe can naturally repel fruit flies. The repelling effect of rue remains disputed, as no evidence currently supports the claim.

Even if fruit flies dislike the plant, no repellant has the power to drive flies out of an area that supports breeding. Furthermore, the plant does nothing to eliminate fruit flies that are already breeding in the home.

Step 3: Sprays or Chemicals

Essential Oils
Most of these products are derived from plant based chemicals so they are safe for kids and pets. Spot treatments applied to areas of high fly activity are most efficient.

For example, flies that tend to rest in dark corners can be controlled by applications to these areas. For cluster flies, treat upper stories of building exteriors immediately before the flies move indoors for overwintering.

Non Toxic Raid

  • Geraniol & Lemongrass Oil
  • Unscented
  • Raid is a well known brand

Dr Killigans

  • Uses peppermint & clove oil
  • Non toxic
  • Works for up to 30 days

Sale
Stem Essential Oils

  • Lemongrass, geraniol, peppermint & rosemary
  • Safe for kids, pets etc
  • Spray directly on flies

Insectides

Pesticides are not typically recommended for fly infestations.  However, it cant help to add another level of protection with a spray or solution designed for household use. 

Permethrin is currently the most common insecticide used for fly control and is widely available. Using an insecticide in replacement, or in addition to an all natural product is the ultimate level of fly elimination.

Below are some insecticides, with good reviews on Amazon.

Permethrin
672 Reviews
Permethrin

  • Water based spray
  • Kills flies, mosquitoes, fleas etc
  • Works quickly

Dinotefuran

  • Manufactured by BASF
  • 16 oz spray
  • Combine it with other traps

Step 4: Prevention

The most common way to reduce the possibility of attracting fly infestations is practicing proper sanitation.  This will eliminate the factors that attract them.

To keep these pests out of the house, homeowners can do the following.

  • Cover all garbage with tight-fitting lids and empty trash frequently to cut down on potential fly breeding grounds.
  • Store food in sealed containers and refrigerate or freeze appropriately
  • Avoid leaving food or dirty dishes out for long periods of time.
  • Clean up litter boxes and pet droppings at regular intervals.
  • Prevent water from pooling in sinks or under appliances.
  • Seal window screen tears and shut doors when not in use.
  • Consistent cleaning of all soap scum and eliminating areas of moisture build up can be effective, as well.

Most Common Flies That Cause Infestations

Fruit Fly

fruit fly magnified
fruit fly
Image credit: MSU.edu

Belonging to the order Diptera, fruit flies, are tiny, flying insects that feed on the nectars and skins of fruits and other plant matter. Ripened plants are especially attractive to fruit flies, who lay eggs just beneath the membranes of fruits and vegetables as they begin to decay. The ripened plants become readily accessible food sources for newly hatched larvae. Degradation of ripe fruits and vegetables caused by fruit fly larvae represent one of the main reasons scientists, homeowners, and business owners often classify the insect as a pest.

The most visible sign of fruit fly infestations consists of the presence of the insect alone. Usually seen swarming around fruits and vegetables left out on kitchen or commercial countertops or in and around refuse bins and other receptacles in which foods are disposed, fruit flies congregate en masse and feed on the decaying plants until food sources shore up. Fruit flies typically remain in areas with viable food sources. Diners, cafes, and restaurants often need to take special precautions to limit fruit fly infestations. Consuming raw fruits and vegetables in a timely manner often reduces the likelihood of infestation. Stowing raw, whole foods in refrigerated or vacuum-sealed units also helps protect against possible swarms of the flying pest.

Traps Specifically Designed for Fruit Flies

Dr Killigans Liquid Bait Trap

  • Designed for fruit flies
  • Non toxic, reusable, looks nice
  • Place it in the kitchen

Sale
Terro Liquid Bait Trap

  • Designed for fruit flies
  • Uses sticky liquid bait
  • Lasts about 45 days

House Fly

house flies
house fly

The entire house fly lifespan revolves around breeding near and feeding on dead and decomposing matter. House fly infestations begin as flies inhabit, mate, and lay eggs in and around feeding grounds. Large numbers of clustering or swarming flies typically indicates an infestation, which can only be eradicated by removing feeding and breeding grounds.

After hatching, house fly larvae feed on their immediate environment, which typically consists of moist feces, rotting animal corpses, or decaying organic materials. Residents routinely find that flies invade their dumpsters, garbage cans, and compost piles.

Female flies reproduce as soon as two weeks after hatching, which means house fly infestations can quickly get out of control. A single fly will lay up to 500 eggs during its 40 to 50 day lifespan.

Flies mature to adulthood within nine to 12 days after quickly moving through the larval and pupal stages. Due to the many eggs female flies lay at once, large populations of flies seem to develop overnight, especially when decaying matter goes unnoticed by humans for weeks at a time.

Phorid Fly

sideview
phorid fly

The most common sign of an infestation remains sighting the insects firsthand. Called scuttle flies due to the propensity of adults to walk or run across flat surfaces instead of instantly flying away, phorid flies may be observed scurrying across counters or buzzing erratically around the room. The appearance of the phorid fly usually coincides with some sort of decaying or festering organic substance in the home. The possibility remains for broken sewage or water pipes under the floors, dirty garbage containers, contaminated soils, and any spoiling produce to invite the insect to settle in and start laying eggs.

In order to keep phorid flies from continuing to pop up in the home, perhaps the most successful way to eliminate the insects remains proper and diligent sanitation. Cleaning any moist areas where organic material may gather over time, such as drains, under kitchen appliances, and any crack or leaks in plumbing lines, will effectively eliminate potential breeding grounds.

In extreme cases, homeowners may turn to chemical insecticides labeled for fly control, which will in turn kill most adults. In cases where home remedies and store-bought chemical solutions fail, contacting a licensed pest control specialist may serve as the best option for a long-term solution.

Drain Flies

Drain Fly
drain fly
Image credit: Matt Bertone, NC State

Drain flies feed on sewage, algae, fungi, and other organic materials

Drain flies mature from eggs to larvae to pupae and then adults. Females lay between 10 and 200 eggs directly in the organic muck that collects in drains. Once these eggs hatch, maggots begin feeding until they form a hard shell in which to pupate. After enough time passes, adults emerge. Summer and spring weather is best suited to drain fly development, and the entire process takes between one and three weeks. Adults live an average of two weeks.

The most apparent indication of an infestation is sighting adult moth flies in the bathroom, kitchen, basement, or wherever else drains are present. Since they are poor fliers, drain flies do not travel far during their two weeks of life. Outdoor drainage sites should also be monitored for collections of the small flies.

Though it is commonly offered as a solution to moth fly infestations, pouring bleach or boiling water down affected drains is not enough to eliminate the problem as the gelatinous buildup will remain and continue to attract the insects. To kill off existing flies and remove the possibility of future infestations, industrial drain cleaner and a hard bristle brush are necessary.

Window screens and other standard preventative measures do not effectively combat the tiny flies. The best way to avoid infestations of drain flies is to regularly sanitize all drain pipes in the home.

Traps Specifically Designed for Drain Flies

InVade Bio Drain Gel

  • Uses probiotics & citrus oils
  • Gel that you pour down the drain
  • Pour it in overnight

Sale
Green Gobbler Drain Cleaner

  • Use in kitchen, showers & bathrooms
  • Contains citronella oil
  • Non caustic