AQUABACxt – Midge Flies in Wastewater

(14 customer reviews)


AQUABACxt is a professional grade, US EPA-registered biological larvicide for use against midge flies and the myriad of issues they cause within a plant, detailed below.

It contains a species of bacteria called bacillus thuringiensis, an approved larvicide for controlling red worms and midge flies in wastewater treatment plants and waterways.  AQUABACxt can either be poured into the aeration basin, or secondary clarifiers, depending on where the redworm problem is.  It also works extremely well in UV disinfection chambers. AQUABACxt has also been proven effective against bristle worms (aeolosoma) and water fleas in the field.

The AQUABACxt Advantage

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™.

*Looking to increase larvicide treatment potency? Learn more about AQUABACxt Companion Products.

*Ask your technical rep for pricing on pallet or tote quantities*

5 Gallon Case

AQUABACxt and Larva-Zyme

Larva-Zyme is a catalyst that degrades cocoons, exposing more of the worms to the Aquabac XT treatment. When used alone, we typically see Aquabac XT kill 70 to 90 percent of the redworm population, and dramatically decrease midge fly activity. By adding Bug Juice to the treatment, we can typically improve the kill to 100 percent, or very near 100 percent.


  • Wastewater Plants
  • Pond Systems
  • Drain Lines


  • Kills Red Worms and resulting Midge Flies
  • Stops Red Worms from eating MLSS
  • Bacterial Based

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. I 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 attract 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, 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.

Companion Products

AQUABACxt + Larva-Zyme: while AQUABACxt alone can kill midge flies, powerful lasting results come when using it in conjunction with Larva-Zyme.

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 BugJuice comes in to aid the larvicide. Red worms will use BOD to build protective cocoons around themselves, which AQUABACxt cannot penetrate. Larva-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.


Midge Flies & Red Worms: What You’ll See


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.

Case Study – UV Disinfection Room

UV-disinfection-room-cleanChallenge: 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.

Solution: They began using our AQUABACxt to rid their system of red worms at the source without harming the good bacteria and BugJuice to degrade the protective cocoons.
Results: This combination was very effective and now they have a UV building that’s not a nightmare to spend time in.

Case Study – AQUABACxt – Midge Flies

Challenge: 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.

Solution: They added a large amount of our AQUABACxt for Midge Flies before the filters and at the clarifiers.
Results: This took them out with one shot, and they now add a little every year to keep the midges flies out.

14 reviews for AQUABACxt – Midge Flies in Wastewater

  1. Larry

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

  2. 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.

  3. Jeramey W. (IL)

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

  4. Holly R. (GA)

    Works great for red worms

  5. Ben F. (IA)

    Very helpful and product works

  6. Josh B. (PA)

    Have always had great results with AquaFix products

  7. 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.

  8. Jason B. (NY)

    Works great!

  9. 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.

  10. Joshua B. (PA)

    Always preforming to eliminate red worms

  11. Billy J. (LA)

    I use your products at my plant a lot. If there is a time period that I go without using the products, you can tell a major difference in the water quality. The chemicals work so well that it overall makes the job easier and makes me stress less on the quality of our wastewater. Thank you guys for providing such great products. I look forward to my next shipment!

  12. Jim H.

    We had large amounts of red worms in our oxidation ditch and clarifier. within a couple months of adding AquabacXT and BugJuice, the problem cleared. Now the plant is looking much clearer and running much better and the results prove that! Thanks for your help and your product, it helped tremendously!

  13. Joseph W. (PA)

    Excellent product and service throughout our experience dealing with your company.

  14. Edward S. (RI)

    1.5 mgd SBR plant. Usually add 2 1/2 gallons twice a year for midge fly control. Great product

Add a review

Your email address will not be published.


Subscribe To Our Water Solutions Newsletter

Join our mailing list to receive the latest news and updates about water treatment solutions. We'll never spam you and your private email information is safe with us.

You have Successfully Subscribed!