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🗎 Midge Fly Complete Product Sheet
🗎 Lar-V-Zyme SDS


Midge Flies in Wastewater

(12 customer reviews)
  • US EPA-registered biological larvicide that is safe and easy to use
  • Improves penetration into the protective cocoon
  • Contains a diverse array of larval toxins to ensure long lasting effectiveness

5 Gallon Case



Eliminate Nuisance Bugs


Red worms thrive in sludge that builds up below aerators.


Masses of red worms congregating at the bottom of a drained aeration basin.


The coating on this clarifier rake are typical red worm cocoons. When scraped, masses of red worms will emerge.


Disc filter media is one of many spots midge flies can burrow in and multiply.

Product Info

AQUABACxt is a highly effective, US EPA-registered biological larvicide. It contains a species of bacteria called bacillus thuringiensis (BT), an approved larvicide for controlling red worms and midge flies in wastewater treatment plants.

Red worms find wastewater plants to be a perfect home. They survive by eating your MLSS, then hatch into midge flies and the cycle repeats. The active ingredient in AQUABACxt kills the red worms and breaks this cycle.

AQUABACxt stands out in the market as it contains 6 complex biological larvicide compounds (called endotoxins) that are highly effective against red worms but safe for fish, birds, mammals, and other lifeforms. With 6 endotoxins, it is difficult for red worms to build a resistance, giving it an advantage over single endotoxin larvicides like Strike™.

Common symptoms of red worm infestations include: disappearing MLSS (the red worms are eating it), stringy or clumpy return activated sludge, and nuisance flies that attract pests. AQUABACxt is safe to use and will only kill a very narrow set of target species; larvae of the mosquito, midge flies, and black flies. It will not cause effluent toxicity issues.

Midge Fly Impact on Wastewater
Midge flies, or chironomids (Chironomidae), commonly occur in wastewater treatment plants and pond systems. The red worm that forms the midge loves the nutrient-rich conditions in a wastewater treatment plant and feeds off bacteria and sludge. The worms will eat mixed liquor and once transformed into adults, clog filters and buildings entrances. Some operators have told us they couldn’t see past their hand in some buildings.

Red worms, also called blood worms, are found in mixed liquor. Over a period of ten days the eggs hatch into red worms and then pass through the pupa stage to become adult midge flies. With no aquatic life to feed on the midges, their life cycle runs uninterrupted, and they multiply fast. If left alone midge flies will cause poor settling, high TSS, and disrupt the bacterial environment. Mixed liquor infested by red worms can see reduced solids, stringy or clumpy sludge, and poor nutrient removal. Not to mention the midge flies are a nuisance that attracts birds and spiders.

*There is no LC50 for aquatic organisms except for mosquito larvae. All other organisms except nuisance flies and midges Psychoda, Chironomus, and Chironomine are not affected by the product. Minnows, fish, Daphnia, and even other aquatic insects can’t be killed by the active ingredient in the formulation. AQUABACxt is specific to mosquito, blackfly, and midge larvae and again is not toxic to anything in the application sites except the larvae of these targets. The LC50 against susceptible mosquito larvae averages 0.15 micrograms per milliliter

Not registered for use in the state of New York.

Dose Rates

Wastewater Plant Dosing
Wastewater Plant Dosing
Wastewater Plant Dosing
Flow Rate (Gallons per day)
Initial Dose (Twice a week for 4 weeks)
Maintenance Dose (Once per week)
100,000 GPD
0.5 gal AQUABACxt + 0.5 gal Larva-Zyme
1 pt AQUABACxt + 1 pt Larva-Zyme
500,000 GPD
2.5 gal AQUABACxt + 2.5 gal Larva-Zyme
5 pt AQUABACxt + 5 pt Larva-Zyme
1,000,000 GPD
5 gal AQUABACxt + 5 gal Larva-Zyme
10 pt AQUABACxt + 10 pt Larva-Zyme
Wastewater Lagoon Dosing
Wastewater Lagoon Dosing
Wastewater Lagoon Dosing
Lagoon Size
Initial Dose (Once a week for 4 weeks)
Maintenance Dose (Once a week for 2 months)
1 Acres
2.5 gal AQUABACxt + 2.5 gal Larva-Zyme
1 gal AQUABACxt + 1 gal Larva-Zyme
4 Acres
10 gal AQUABACxt + 10 gal Larva-Zyme
4 gal AQUABACxt + 4 gal Larva-Zyme
8 Acres
20 gal AQUABACxt + 20 gal Larva-Zyme
8 gal AQUABACxt + 8 gal Larva-Zyme

Product Pairings

AQUABACxt is a highly effective, US EPA-registered biological larvicide, but to work it must be able to reach the red worms. This is where Lar-V-Zyme comes in to aid the larvicide. Red worms will use BOD to build protective cocoons around themselves, which AQUABACxt cannot penetrate. Lar-V-Zyme is a biocatalyst that specializes in dissolving tough forms of undigested BOD. Larva-Zyme is able to easily degrade the red worm cocoons so that the AQUABACxt can fully reach the red worms.

Applications and Benefits

  • Wastewater plants
  • Pond systems
  • Drain lines
  • Kills red worms and resulting midge flies
  • Stops red worms from eating MLSS
  • Bacterial based

Case Studies

Case Study – UV Disinfection Room



A 6.5 MGD wastewater treatment plant in Wisconsin was dealing with a UV disinfection room that was always covered in midge flies. The operators were constantly cleaning the room and had installed bug zappers to try and control them. Unfortunately killing the flies did no good as new ones were constantly developing in the clarifiers.


They began using our AQUABACxt to rid their system of red worms at the source without harming the good bacteria and Larva-Zyme to degrade the protective cocoons.


This combination was very effective and now they have a UV building that’s not a nightmare to spend time in.

AQUABACxt – Midge Flies



A 3MGD wastewater treatment plant in Wisconsin had an issue with blood worms and the resulting midge flies in their Hydrotech disc filters. The filters were filled with worms and it got worse every day.


They added a large amount of our AQUABACxt for Midge Flies before the filters and at the clarifiers.


This took them out with one shot, and they now add a little every year to keep the midges flies out.


12 reviews for AQUABACxt

  1. Ronald Bruce (TX)

    The only bloodworm eradication program that has exceeded my expectations. We will continue using AQUABACxt from now on.

  2. Ashley Lynch (GA)

    I discovered Aquafix several years back when searching for a product to get rid of our midge fly larvae infestation. We were so happy with the products price and quality that we haven’t looked elsewhere since. I highly suggest giving Aquafix products a go, as you won’t be disappointed!

  3. William H. (LA)

    This product works wonders in our Wastewater plant. We can always depend on it to work towards protecting the integrity of our wastewater. It prohibits harmful bacteria from being able to do anything to your water.

  4. Steven C. (PA)

    I have been using Aquabacxt in my plant for 5 years. When i took over managing the operations, there was a tremendous amount of Midge flies and larvae in the aeration process. It was an operational nightmare. I started dosing it and within three months, there were no signs of midge flies or the larvae. I just do small weekly maintenance doses now and have not seen a midge fly larvae in years. Definitely an added bonus to your arsenal.

  5. Jason B. (NY)

    Works great!

  6. Susan H. (MD)

    We had a abundance of red worms in our SBRs. They were eating up the sludge blanket creating issues with the nutrient removal at the plant. The AQUABACxt and BUG JUICE took care of the problem and the plant is back In compliance.

  7. Josh B. (PA)

    Have always had great results with AquaFix products

  8. Ben F. (IA)

    Very helpful and product works

  9. Holly R. (GA)

    Works great for red worms

  10. Jeramey W. (IL)

    Very happy with this it does its job knocking down the midge flies

  11. Jeff

    Works slick, they got so thick in our sand filter building we could hardly breathe. AQUAFIX told us about the AQUABACxt and it works.

  12. Larry

    We had bad red worms in our sand filters. AQUABACxt knocked them out.

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