Cluster flies closely resemble house flies and are easy to mistake one for the other. Their behavior is quite different, however, and this difference is usually enough to determine which you have.
CLUSTER FLY BIOLOGY
Cluster flies are parasites of earthworms. Adult females lay their eggs in the soil. When the larva hatch, they seek earthworms as their food. The larva burrow into the worm and feed on it for up to a month. Once it gets its fill, it leaves the worm to pupate. It does so in about two weeks and then emerges as an adult which feeds on shrubs and flowers. It is prevalent throughout the entire United States and will be able to complete up to 8 generations in any season.
CLUSTER FLY LIFE CYCLE
Cluster flies are a nuisance because they live a long time. In fact, most other flies live less than three months. Cluster flies, however, can live for two years or more. To endure the harsh winter, they will hibernate. This is what causes conflict with man.
Cluster flies grow in the ground. Female flies lay eggs in the soil which hatch larvae that seek earthworms. Using the worm as a host, the larvae will feed inside the worm. This will not affect the worm. After it gets its fill, the larvae leave the worm and pupate in the soil to emerge as the adult fly. Over the course of the summer, this pattern will play out. Females mating, laying eggs in the soil, feeding on worms as larvae, pupating in the ground to adults and then leaving to seek a mate.
In the fall, Cluster flies will migrate into the siding of homes and other buildings. There they stay until warm weather and spring. Homes which attract cluster flies seem to attract more each year. This happens because once a home is “marked” as a good location on which to hibernate, pheromones will be left on the home signaling to other flies to come and nest here too. The first few years of having the flies stay all winter go undetected but at some point their population will start to find their way inside and once that happens, it can be an ongoing problem for many years if left untreated.
Cluster flies will migrate inside seeking heat. And in the spring, it can happen more by mistake. It is not uncommon for some of them to mistake a warm winter day as spring. Once they awake they will move to where it is warm. This may turn out to be inside your home. They crawl out around molding and vents, warm up and become an instant pest. Most people are at a loss when trying to understand where they came from and will spend a lot of time and effort trying to control them. Once identified, there is a way to get control.
HOW TO TREAT A CLUSTER FLY PROBLEM
Cluster flies can be hard to control but there are options. You will need to do several things to break their cycle and stop them from living in your home.
BEST CLUSTER FLY SPRAY FOR THE HOUSE
On the outside of the home, spray with MAXXTHOR EC. This fast working concentrate will keep them off the structure by repelling them immediately.
Spray from the gutters down to where the ground meets the foundation using our GREEN HOSE END SPRAYER.
The following “short video” (less than 60 seconds long) shows how to use it in our sprayer:
Next, spray around the home. Since cluster flies come from the ground, its important to eliminate your grass, mulch and pine straw as places for them to be reproducing.
If using a pump sprayer, mix 1 oz per gallon of water in a standard PUMP SPRAYER to treat the home. Use 1 gallon of mixed product per 500-750 sq/ft and renew as needed; once a month will usually be enough to keep them off the home. But for most people, the hose end sprayer will be better as it will allow you to apply a lot more product faster and this is usually needed for this fly.
This PUMP SPRAYER will reach up 15 feet and can be adequate for most homes.
But if you need to reach higher, our HOSE END SPRAYER will use the power of your garden hose and reach as high as the hose will spray.
This video show why this particular sprayer is well suited for the task of applying up high:
Add 2.5 oz of Maxxthor to the sprayer, fill it with water to the 5 gallon line and then hook it to your hose to treat. Use the entire amount to treat up to 5,000 sq/ft of home or turf.
BEST TIME TO TREAT CLUSTER FLIES
We get this question quite a bit and the quick answer is from spring through fall. Here’s why.
First, in early spring, cluster flies living under your homes siding or in the attic/wall voids will exit your home to go off and live their life outside for the summer and fall. So if the homes exterior has been dusted and sprayed prior to them leaving in early spring? Many will die so the amount returning the following fall will be greatly reduced.
Second, any that are using the ground around your home to lay eggs will be returning all spring and summer. Even though you don’t see them on your home, they will be in the turf. But spraying it will Maxxthor will both kill them AND keep their eggs from thriving.
Remember, cluster flies live several years AND their offspring is “pre-wired” to target the home where they were first created. By killing off any regenerating in your yard will in turn reduce the amount coming back in the fall to use your home for hibernation.
Lastly, in the fall, renewing the exterior spraying is vital to both kill and repel any survivors who will be per-disposed to target your home.
So in summary, spray the homes exterior siding in the spring and during the summer, spray your turf every 4-6 weeks (this will also prevent ants, roaches and other pests). And be sure to spray the homes exterior siding in the fall to prevent the natural migration they make into homes they’re using for over wintering.
DUST WALL VOIDS AND EXTERIOR SIDING FOR THE LONGEST LASTING PROTECTION
On the homes siding, in the attic and deep in the wall voids where cluster flies like to nest should be dusted with DEMISE DUST. Using a CRUSADER, you can puff small amounts up under the exterior siding, into any cracks or crevice common to log homes and into all crevices they might choose to use for hibernating.
The following “short video” (less than 60 seconds long) shows how to treat your homes siding which for Vinyl, Aluminum, Wood Shakes or Stucco will be required.
Demise is long lasting meaning it can provide 6-12 months of protection. More important is that Demise will effectively absorb and remove the long lasting pheromone smell which is the reason they keep coming back. Demise is highly repellent to any insect so where applied, nothing can live or nest.
Demise goes a long way. 6oz will cover 1000+ sq/ft of wall space or under exterior siding. Renew once a year to ensure long term control.
3.5 OZ or 6 OZ
Use this duster to apply the Demise. It only takes 2-3 squirts every 3-4 feet and as you treat, watch how far the dust floats to ensure you’re getting adequate coverage.
If you don’t feel like climbing a ladder to apply the dust, use our DUSTICK.
It features 4 foot extensions so you can reach up 30 feet or more to get every row of siding properly treated.
The following “short video” shows how the Dustick is used:
The Dustick is an investment but will pay back by both keeping you safely on the ground and saving time.
In attics, use a DUSTIN MIZER to blow the dust out.
Cluster Flies love attics but dusting it good with Demise will keep them from using it for many years.
The following video shows how the Dustin Mizer works for attics or crawl spaces:
Again, use 1 lb for every 1500-2000 sq/ft. In protected areas like attics, treatments can last at least 12 months.
HOW TO TREAT CLUSTER FLIES ON WINDOWS
During the winter, cluster flies can become a real problem as they migrate into living spaces. If a house is “scented” and luring cluster flies inside, they tend to accumulate around windows.
To help manage the problem, you have two options.
PAINT WINDOW FRAMES WITH ALPINE
The most “effective” approach is to “paint” on some ALPINE WSG. Alpine is a unique product in that its non repelling and won’t spook or scatter insects. When painted onto window frames and the surfaces around the window, flies going there will get exposed and in 1-2 days die.
Alpine is odorless and we suggest “painting” it so your treatment is precise and won’t make a mess.
Add one packet to 1/2 gallon of water and use up the mixture in 3 days.
Plan on treating twice week until the fly activity ends. Also expect to be vacuuming up a lot of dead flies!
FOR DEEP PENETRATION FS MP AEROSOL IS BEST
Now for deep penetration, you’ll need our FS MP AEROSOL. Its both quick killing and highly repellent so it will kill all stages nesting and reproducing in the walls and around the window. But more importantly, it will repel the new ones coming to your home which often times use the window as a main route of entry.
Since windows are so important when treating for cluster flies, we did a whole video which shows nothing but how to properly treat a window. This worth the watch if you have cluster flies nesting around window frames:
Spraying these cracks and crevices with FS MP AEROSOL. will offer a quick kill and repellency since they don’t like FS MP and avoid the area. Use it once a week when flies are active.
Another option is to install AEROSOL MACHINES equipped with CLEAR ZONE REFILLS. These machines run on batteries and can cover up to 400 sq/ft per machine. Once powered on and filled with a can of Clear Zone, they’ll work around the clock by releasing a small 1/2 second blast of pyrethrin based spray strong enough to control any flying pests like mosquitoes, gnats, flies, moths and more.
The following “short video” (less than 60 seconds) shows how easy these machines are to use and why they’re so effective for any flying pest:
Set up machines close to any window where cluster flies are active and they’ll quickly die.
Fit each machine with a can of CLEAR ZONE. This spray is safe enough to be deployed in any room including kitchens and bedrooms. Cans will generally last 30 days when set to release every 15 minutes.
Lаѕtlу, thе SPARROW HAWK FLY TRAP саn bе dерlоуеd іn аnу rооm whеrе аdult cluster flies аrе ѕееn. It’ѕ amazingly well adapted for catching flying insects like mosquites, noseeums, drain flies and more. It has a large glue board that catches them once they enter the holes on the outside band. Keep one installed in kitchens bathrooms or bedrooms where pests have been seen.
Here is the kit that features the Sparrow Hawk with our Aerosol Dispenser and a can of Clear Zone.
Give us a call if you need further help. Our toll free is 1-800-877-7290 and we’re open Monday through Friday, 9:00 AM to 6:00 PM. (Eastern Standard Time).
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