TERRO® Drain Insect Killer is a powerful solution that targets insects in your drain, including drain flies, fruit flies, house flies, and roaches. It works by using three Insect Growth Regulators to break the insect lifecycle, stopping the infestation in its tracks. The dry foam formulation reduces the chances of missed areas and provides complete drain coverage for effective insect control.
Targets Drain Insects
TERRO® Drain Insect Killer contains three Insect Growth Regulators (IGRs), which disrupt the normal development of immature drain flies, fruit flies, and roaches. Additionally, it disrupts the normal life cycle of drain flies and fruit flies, effectively eliminating them during their pupal stage, thereby breaking the cycle of infestation.
Dry Foam Formulation
TERRO® Drain Insect Killer features a unique, dry foam formulation that expands to provide full-contact, 360-degree drain coverage. This allows you to reach areas that liquid drain products can’t, making it highly effective in tackling and preventing insect infestations. The visible foam also ensures that no areas are missed during application.
Easy to Use
Apply TERRO® Drain Insect Killer into and around the downspout and catch basin. It's important to thoroughly coat these areas, as fly larvae develop in the scum buildup on the sides of drainpipes. When treating a double-basin sink, apply it in both drains. The fold-up extension tube allows for precise application into the pipes. Reapply every 2 to 4 weeks depending on the severity of the infestation.
TERRO® Drain Insect Killer Details
Do you want to know more helpful details about the TERRO® Drain Insect Killer? Take a closer look at the in-depth specifications for this product.
TERRO® Drain Insect Killer
Model #
T590
Active Ingredients
(S)-Hydroprene, Novaluron, Pyriproxyfen
Eliminates
Drain flies, fruit flies, house flies, and roaches
Drain flies were a daily issue until I found TERRO Drain Insect Killer. Used properly the foam blocks drains and truly eliminates the pesky problem. For several days I used daily & then was able to taper use to twice weekly. TERRO is the only product I found to solve the problem. Also they have a most responsive and helpful customer service department. They back their products. Thx to Walter with a dispensing issue.
Drain flies will drive you crazy but TERRO works!
Additional tip: cover drains at night.
Not only was I forced to use a magnifying glass to read the label, but it also does not tell you when you can start using the sink drain after applying the product. Used roughly 1/2 can and the remaining amount was wasted. Initially bought 2 cans but will return the unused one.
Thank you for your feedback. We're sorry to hear about your experience and understand your frustration with both the label readability and the product instructions.
We appreciate your comments regarding the size of the text on the label. Clear and accessible instructions are important, and we will share your feedback with our product team for review.
To clarify, the foam should be left in the drain for at least 15 minutes to allow it to work effectively. After that time, the drain can be used again. We understand that this information may not have been as clear as it should have been.
We're also sorry to hear that you felt a portion of the product was wasted and that it did not meet your expectations. We value your feedback and will use it to help improve both our packaging and product information moving forward. Thank you for taking the time to share your experience.
AB
I don't recommend this product
Product etched the finish around ...
1
May 23, 2026
Product etched the finish around my gold/rose colored sink drain and stopper after leaving about 30 min! Very upset about this., as the sink is new. Instructions super difficult to read on bottle, so looked it up online but did not read a warning about possible damage to finish.
We’re sorry to hear about your experience with TERRO® Drain Insect Killer and the damage to your sink finish. This product is intended for use in drains and may not be suitable for all decorative or specialty metal finishes. We understand how frustrating this must be, especially with a new sink. We appreciate your feedback regarding the label readability and warnings, and we will share your comments with our product team for review.
Pegge
I am not rating this ...
1
Apr 17, 2026
I am not rating this product because I can't read the tiny instructions on the can. Therefore, I will not be using it, and I will return it to the store.
We’re sorry to hear the instructions on the can were difficult to read. We understand how important clear directions are for proper use.
For your convenience, all instructions and product information for TERRO® Drain Insect Killer are also available on our website in a larger, easy-to-read format.
Doug
I don't recommend this product
Can must be turned to at least 90 degrees causing only air to exit the can after about half is used. So about a quarter of the product is wasted.
2
Apr 1, 2026
The product seems to kill drain flies effectively. However, my frustration is that when spraying the foam into the drain, the can has to be turned to at least a ninety degree angle.. After about half of the can is used, only air to come out of the straw and leaves about a quarter of the product unusable. It would be extremely helpful if you included a longer flexible tube as well like similar products have.
Thank you for sharing your feedback. We’re glad to hear the product is helping control drain flies, but we’re sorry for the frustration with the application and can performance. Your comments about the spray angle and tubing are appreciated, as they help us improve our products.
Jimbo
I recommend this product
We were infested with drain ...
5
Aug 23, 2025
We were infested with drain flies with one application of terro they were eliminated. I am so satisfied with the product I had to give a 5 star review
How long should you let this sit after applying it, before you run water in the sink?
Question by: Angela on Jul 24, 2025, 7:18 PM
Wait 15 minutes before running water after applying TERRO® Drain Insect Killer.
Answer by: Brandon (Admin) on Jul 25, 2025, 10:23 AM
Aerosol cans need to be upright to use all the contents. The nozzle is too short to hold the can upright and still reach into drains Is a nozzle extender available?
Question by: Joanne on Nov 22, 2025, 11:58 AM
Yes — the can comes with a fold-up extension tube which acts as a built-in nozzle extender so you can apply the foam deep into the drain pipe.
Answer by: Walter Sandoval (Admin) on Nov 24, 2025, 9:07 AM
Hi, Do you offer a trial size?
Question by: Gwen on May 6, 2026, 12:11 AM
At this time, the TERRO® Drain Insect Killer is only available in the standard 8 oz size and we do not offer a trial size.
Answer by: Walter Sandoval (Admin) on May 6, 2026, 10:55 AM
There is a drain fly infestation in a home shower. The drain flies are coming from behind cracks in tiles, wall voids, and faulty caulking. Can I spray this in those areas, let it do its thing, use fans to dry it thoroughly before eventually sealing it up without ever needing to (or being able to) remove the product from behind the tile and wall?
Question by: James on Jul 20, 2026, 1:44 PM
Hi, thank you for reaching out. Thank you for your question.
This product was designed specifically for use in drains, where it can be applied according to the label directions. We have not tested the product for use inside walls, behind tiles, or in wall voids, so we cannot recommend applying it in those areas.
For areas such as cracks, wall voids, or damaged caulking, we recommend addressing the source of the infestation and repairing any openings where flies may be entering or breeding.
Thank you, and we hope this information helps.
Answer by: Guillermo (Admin) on Jul 20, 2026, 2:41 PM
I used product yesterday and saw decrease of drain gnats.How soon can I use it again if I feel it necessary ?
Question by: Pat on Dec 2, 2025, 11:24 AM
Hi, thank you for reaching us. Depending on the severity of the infestation, it's recommended to repeat the application every 2 to 4 weeks.
Answer by: Guillermo (Admin) on Dec 2, 2025, 3:13 PM
