Ortho Orthene Fire Ant Killer (Works for Roaches Too!)

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Updated on April 13, 2023

If you’re looking for an effective and easy-to-use solution to your fire ant problem, Ortho Orthene Fire Ant Killer is a popular choice. This product not only kills the queen and destroys the mound, but it also requires no watering-in to be effective.

Best of all, it’s easy to apply and starts killing fire ants, red harvester ants, and other ants in just 60 minutes, so you can get back to enjoying your yard fast.

Surprisingly, Ortho Orthene Fire Ant Killer works great for eliminating roaches as well! Here’s everything you need to know about Orth Orthene including how it works, how to use it, and other frequently asked questions.

What is Ortho Orthene?

Ortho Orthene is a form of insecticide that is designed to kill fire ants, other types of ants, and even various roaches. It comes in a 12-ounce container of granules.

Ortho Orthene works by interfering with the ant’s ability to digest food. This causes the colony to starve and eventually die. Ortho Orthene can also damage the ant’s nests, making it harder for them to reproduce. While the granules may smell like rotting cabbage to humans, they work very well at their intended purpose.

Ortho Orthene Fire Ant Killer
  • Starts to kill in hours
  • No watering-in required
  • Reduced odor formula

How It Works

Ortho Orthene works by disrupting the nervous system of pests and causing paralysis and death. The active ingredient is acephate, a type of pesticide known as an organophosphate.

This pesticide works by inhibiting an enzyme in the nervous system of the pest, causing paralysis and death. The product is most effective when applied directly to the pest or an area where the pest is likely to be found.

When to Apply

The best time to apply insecticide is during the daytime although any time you spot an infestation is a good time to use it.

Ortho Orthene for roachesHow to Use Ortho Orthene Fire Ant Killer

On Fire Ants

  1. Locate the fire ant mound. Fire ant mounds are usually found in sunny spots in yards, gardens, and parks.
  2. Carefully apply Ortho Orthene. Shake the product well before use and be sure to follow the directions on the product label.
  3. Apply the product directly to the fire ant mound. The product should be applied in a band or circle around the mound, extending six to twelve inches beyond the mound’s edge.
  4. Wait. Allow the product to work according to the product label instructions.
  5. Repeat. If necessary, reapply the product according to the instructions on the product label.

See Also: How to Get Rid of a Fire Ant Infestation

On Roaches

  1. Clean up the area of infestation.
  2. Sprinkle some Ortho Orthene granules in areas around where roaches are found. Ensure that pets or children cannot access the areas where the granules are found.
  3. Roaches should be fully eliminated within 2-3 weeks of application.
  4. If any roaches are still seen after that time, repeat the application process.

Does Ortho Orthene Fire Ant Killer Work On Roaches?

While it was originally made for fire ants and could kill them with remarkable efficiency, Ortho Orthene has shown remarkable effect against cockroaches.

This is due to the fact that it has Acephate as the active ingredient. Acephate is an organic insecticide that controls insects like aphids, ants, and also roaches.

Another reason it’s effective against roaches is that it has residual activity of about 10 – 15 days. This moderate period ensures that you’ll be able to get rid of them effectively.

What Does Orthene Get Rid Of?

Orthene is able to kill a vast majority of pests like ants, roaches, aphids, armyworms, bagworms, flower thrips, mites, mealybugs and a few more insects.

Is Orthene Toxic?

Yes, it’s toxic to some extent. Organophosphate exposure can cause respiratory paralysis and death in children and adults. Children may experience the following symptoms – seizures, lethargy, coma, muscle weakness, miosis, and excessive salivation.

Is Orthene Safe for Pets?

It’s not lethal to mammals in small doses, but if exposed to too much of it, results can be fatal. The smell is foul, but I think the idea behind it is just to keep pets away while your house settles.

Can Orthene Be indoors?

The active ingredient in Orthene is Acephate and it can be applied as a high-grade insecticide to control cockroaches and ants. It controls insects outside and inside your home, while being safe to use around people.

How Long Does It Take Orthene to Work?

For fire ants and other small insects, it can take as little as 60 minutes to see results. For roaches, it may start to work as quickly, but may take days to fully eliminate a roach infestation.

How Do You Get Rid of the Smell of Orthene?

It is advised to use the product outdoors but if using indoors, make sure there is plenty of ventilation. The smell of the product can be reduced by letting it sit for several hours, in an area where a cedar mulch has been added.

Is the Smell of Insecticide Harmful to Humans?

Plant-derived chemicals called pyrethrins are generally not harmful, although they can cause life-threatening breathing problems if breathed in.


Orthene Fire Ant Killer can be toxic to humans and pets. You should handle it properly when using it.

The following precautions will suffice.

  • Do not mix with water.
  • Also, don’t apply it in areas that lead to waterways like drains.
  • Handle with a hand glove.
  • Don’t allow it to enter your eyes or mouth.
  • Keep away from pets and little children.


  • Very effective
  • Easy to use
  • It doesn’t need any other product


  • Has a bad smell
  • It can be toxic if not handled properly

What are the risks of using Ortho Orthene?

There are some risks associated with using Ortho Orthene to kill fire ants. First, the product can be harmful if it gets in your eyes or if it’s breathed in.

Second, Ortho Orthene can also damage your skin if it’s sprayed directly on you. Finally, Ortho Orthene can affect other animals and plants if it’s sprayed near them.

Final Thoughts

Orthene Fire Ant Killer is an effective insecticide that is not harmful to plant life. It not only works for fire ants, but also a variety of other common pests including various types of roaches.