Gentrol Insect Growth Regulator for Drain Flies

Gentrol Insect Growth Regulator (IGR) effectively breaks the insect life cycle and prevents future infestation. It is commonly used for drain fly, cockroach and bed bug control. Gentrol IGR is also approved for use in food handling establishments and provides 120 days of pest control.

What Is Gentrol?

Gentrol was developed by Zoëcon® products. Its main purpose is to controls insects by interfering with normal development. It also disrupts the life cycle, killing insects during the pupal stage.

This mode of action provides IGR control to prevent the growth and/or maturation of labeled pests. In our case, this includes drain flies. The primary ingredient in Gentrol is hydroprene, which has a very low toxicity classification from the EPA.

When Do You Need Gentrol IGR?

If you have a heavy drain fly infestation, Gentrol IGR can help improve treatment success rate by preventing adults from continuing to lay more eggs. This is important considering that drain flies will lay up to 100 eggs at a time which can hatch in two days time.

There are many talked about solutions on the web. Some include all-natural compounds and solutions, while other take a more drastic approach. However, few cover the use of Gentrol in the treatment and prevention program.

Applying Gentrol Aerosol

bathroom drain

One of the easiest application methods for Gentrol is their ready-to-use pressurized spray. You can simply spray down into a drain along the side walls to get a good coat. Generally, this method is part of a treatment program that also includes a drain gel and some manual pipe cleaning.

By combining all of these elements, you will kill and prevent adult flies from producing more offspring. Otherwise, you run the risk of seeing very short-lived success and continuing infestation in the long term. This is where a DIY drain fly kit can be helpful for small to medium infestations.

Apply as a general surface spray, spot, or crack and crevice application. The supplied extension tube makes treatment of crack and crevice applications easy. Hold can ten to twelve inches from the surface to be treated. Gentrol applies as light foam that dissipates over time, so it is easy to ensure you don’t miss areas.

For drains, spray Gentrol into and around the downspout and catch basin area. Fly larva develop in the scum buildup on the sides of drain pipes. Coat the sides of the drain thoroughly. Repeat applications at 2 to 4 week intervals.

Does Insect Growth Regulator Work?

This is a tricky question because Gentrol IGR will not eliminate drain fly issues by itself. Most individuals combine the spray with other treatments methods. If the breeding ground is not eliminated, you are only solving half of the issue. Additionally, you need a good sanitation program to prevent future buildup in drains and areas with standing water.

Key Information

Active IngredientsActive Ingredients: 0.36% (S)-Hydroprene
ApplicationDissipating foam action to target insects in hard-to-reach areas
YieldTreats up to 1,200 square feet
Sale Restrictions NY (Commercial Applicators Only) residents may purchase Gentrol Concentrate.
Made byZoecon
EPA Registration Number2724-484
UseGentrol® IGR prevents rebound infestations

See PDF of label

Questions and Answers

Can this product be used on pets or humans?

No. Gentrol is not meant to be used directly on humans of pets. However, it is safe to use in living environment when following directions. See the label for further reading.

Does Gentrol Aerosol Kill Adult Flies?

No. Gentrol IGR is meant to disrupt the breeding cycle and prevent future flies. It will not kill insects on contact. If you are looking for a contact killing spray, such a raid or a more professional higher grade pyrethrin product.

Can I mix this spray with DF5000 drain gel?

Yes. We recommend using Gentrol aerosol with DF5000 drain fly gel which will help remove organic matter buildup inside drain pipes. (Which is where larva live and flies breed.)

Reviews from Around the Web


We had an infestation of drain flies after a busted pipe was repaired under our kitchen slab. The plumbing company sprayed our drains and cleaned them by flushing them with hot water. They charged us $165. However, three weeks later, we still had them in the hundreds.

I ordered Gentrol from DoMyOwnPestControl, and am very happy with the results. We are only seeing one or two on occasion and with another application or two we should be rid of them entirely. This company has excellent products and service. The shipping was fast and the product well packaged. Love the free shipping. I will definitely purchase from them again.

Not a Cure…

I have purchased this product as well as others from this site to eliminate sewer flies. None of them worked. The truth is that sewer flies are caused by a break in a sewer or waste line and these products may seem to work at first, BUT they will not eliminate the need for fixing a pipe or dealing with a plumbing problem. 

Do yourself a favor — I spent over $100 on products from this company including Gentrol. They do NOT eliminate sewer flies.

Important Note

It is unlikely any single product will cure drain fly issues. You need to build a complete program that includes cleaning pipes, using drain gel and developing good habits to prevent future buildup. There are times when flies breed under a slab in the seepage from a broken sewer line. In this case, you will need professional help to ensure that is the issue, and then to fix the sewer line.

Good Product

It took a few months but we finally got rid of a drain flies infestation which we have had for about a year. We believe it was the Gentrol that did it, although we’ve used a variety of products in our jacuzzi tub where the largest number of flies were present.

Drain Fly Killer

This product seems to be working good. We had a terrible problem in our bathrooms and we have been using it every 2 weeks. It seems to be controlling the infestation.