Thatching Ants: How to Get Rid of Thatch Ants

Thatch ants are well-known for making mounds from pine, leaves, grass stems, or small sticks. These red and black insects are considered beneficial to the world’s ecosystem because they fiercely prey on other insects. Nonetheless, thatching ants can be a nuisance when they infiltrate into your home or other properties.

How to get rid of thatch ants? There are many effective eradication methods that can be used to get rid of the thatching ants. The application of ant baits is the best control method for thatching ants but it takes a few days to start working. Other methods include the use of different liquid or powder pesticides. Also, some natural methods can help you get rid of the thatching ants such as trimming the backyard tree branches regularly, caulking crevices and cracks, and applying different natural ant repellents.

Ant Exterminators

The presence of thatch ant mounds can visually disrupt the landscape and make affected land unproductive. Besides, thatch ants are a threat when they invade your house. For instance, they bite fairly hard and in the end, they spray formic acid that brings a painful sensation. If the skin is not washed, you might develop blisters.

So you don’t want to take chances whenever you spot a thatch ant around your house. Save yourself the ordeal by using one of our methods or a combination of them.

What Are Thatching Ants?

What Are Thatching Ants

Thatching ants (Formica obscuripes) are quite large ant spices (0.157 to 0.3149 inches or 4-8 mm in length) that build mounds or so-called thatched nests. Wester hatching ants are native to North America, they can build their nests pretty big and their average colony size is around 40000 worker ants.

• What Do Thatching Ants Eat?

These ants feed on sugary substances. Thus when they invade your home, they will often look for sugary foods. Besides, they eat various insects such as dead moths, small beetles, and caterpillars.

• The Difference Between Thatching Ants and Carpenter Ants

It is very easy to confuse thatching ants and carpenter ants. The easiest way to differentiate them is to view them from their sides. As you do so, focus your attention to see the appearance of the top part of the thorax. Carpenter ants have a smooth and rounded thorax while thatch ants’ thorax has a dip or notch.

How to Get Rid of Thatch Ants: Methods and Instructions

How to Get Rid of Thatch Ants

Step 1: Find and Destroy Thatch Ants’ Nests

Finding the nests of thatch ants can be difficult if only a few of these insects are spotted around in your house. However, knowing their likely hideouts can ease this process. For instance, they usually form their nests in decayed logs. Besides, thatch ants create mounds from grass stems, small sticks, pine, leaves and fir needles.

After you find the nest, it is advisable that you destroy it completely if you determine that they are behaving as pests (in some cases they are beneficial to the environment). To destroy their nest, it is recommendable to use pesticides in order to kill these insects and prevent them from migrating.

Step 2: Apply Pesticides

• Ant Baits

The best way that you can get rid of thatching ants is by using ant baits that contain hydramethylnon or boric acid. You need to ensure that you have repeatedly applied baits for the effective elimination of these insects. Each time you spot a thatched ant, it is an indication that there are many others residing near your house. Those that you see are typically the scout ants. They are searching for food that they will eventually take back to the colony. You can use the scout ants to trace the nest and thus get rid of the whole colony.

It is worth noting that the tastes of thatching ants keep on changing throughout the year. Most thatch ants prefer fatty sweet foods during summer and protein during the spring season. So set out different types of baits to find out which one will attract these ants. The scout ants in the process of hunting food for the colony will find the bait and take it to the colony. Since it contains the taste that is preferred by the thatched ants, they will consume the bait (including the queen) and the whole colony will die. The following are one of the best ant killer baits.

TERRO T1812 Outdoor Liquid Ant Killer Bait

TERRO T1812 Outdoor Liquid Ant Killer Bait Stakes - 8 Traps
  • Attracts & Kills – Kills common household ants including...
  • Kills the Ants You See & the Ones You Don't – As worker ants...
  • Works Fast – You should see a significant decrease in the...
  • Ready to Use – Insert stakes and break the tab, then watch it...
  • For Outdoor Use – Place the bait stakes in outdoor areas where...

Home Plus Ant Killer, Metal Ant Traps Indoor & Outdoor

Homeplus™ Ant Killer AB , Metal Ant Bait, Ants Killer for House, Ant Traps Indoor & Outdoor, 4 Pack
  • Metal Ant Killer Bait: Attracts and kills many different species...
  • Food Lure Ant Bait: The child-resistant metal bait stations use 4...
  • How it Works: Worker ants carry and share the bait with the rest...
  • Quick Results: Starts killing worker ants within 24 hours; you...
  • Usage: Homeplus Ant Killer AB baits are great for getting rid of...

• Other Pesticides

Thatch nests can also be eliminated using pesticides such as pyrethroids, pyrethrin, boric acid and others. These pesticides should be applied to nests or crevices and cracks that are used by the insects as access points. When spraying the nest, you can even use multiple chemicals to eliminate thatching ants quickly and prevent them from relocating.

The majority of people opt for organic options while others prefer using strong pesticides. Using either of these options is a good move as long as it is effective. You should make sure to completely saturate the mound. If you treat the top layer only, the pesticide will not be effective because only the ants on the top area will be killed. You should be aware that the queen usually resides two to three feet underground in the mound.

If the mound is not well-saturated with a pesticide, the queen will continue to live and reproduce. This will make it more difficult to get rid of the thatch ants. To ensure that the mound is properly saturated, it is recommended that you mix the pesticide with water. You can also hose down the mound before spraying it with the pesticide. This will help with saturating it.

• Spot Treatment – Please Read

You can also get rid of the thatching ants by using spot treatment on their nests. This should be done using a residual insecticide that is already registered for controlling ants. You do not need to spray residual insecticides on a large surface, you just need to focus on the entry spots of their nests.

Note: It is worth noting that groundwater may be contaminated when the earth is saturated with pesticides. So it is vital to be cautious when using pesticides.

Step 3: Trim Backyard Tree Branches Regularly

Trees next to your house offer a shade that produces a cooling effect for the thatching ants. In fact, fruit trees such as pears and figs not only offer shade but also provide food for them. While backyard trees may have several benefits, they can be a haven for ants. You might wonder how ants find their way into your home yet you don’t find them wandering around your front door. If you spot thatch ants in your home, they could be accessing your house through routes such as tree branches that touch your roof.

So trimming these branches is a great way to get rid of the thatch ants. Ensure that you trim your backyard trees regularly. Besides, ensure to undertake lawn care maintenance often. In doing so, you will not only prevent ants from invading your home but will also keep your surroundings beautiful.

Step 4: Caulk Crevices and Cracks

Thatch ants are particularly industrious in discovering entry points such as crevices and cracks around foundations, walls, windows, and doors. Identify all these openings that offer access from outside. Then block all these routes using silicone-based caulk or other types of caulk.

Almost all types of ants like to make trails along pipes, wires, and other structural elements. Mostly, they use these elements to enter a house. So examine locations where pipes or other elements enter your house and caulk identified entry points.

Step 5: Remove Ant Trails

Thatch ants leave behind a scented trail that helps other ants from their colony to find your house. You can get rid of these trails in order to eliminate these insects completely. Mix vinegar with water and spray the mixture around your home to prevent outdoor ants from getting into your house. This will prevent outdoor ants from accessing your home.

Then, use insecticides or another method to eliminate the indoor ants (we suggest natural ant killer sprays).

What If None of These Works? | Hire a Skilled Exterminator

If none of these methods work, it’s time to call an exterminator. Hiring an experienced exterminator is probably the most expensive option. However, it is not only a highly effective method but also increases safety during the thatching ant treatment process.

A skilled exterminator will quickly discover the origin of a thatch ant infestation. Usually, these professionals use a combination of methods. With their skills and tools, they can deal with any ant infestation in one day (number of days depends on the severity of the ant infestation).

Related: Ant Exterminator Cost | Ant Treatment Price Guide


Sometimes, thatch ants can be hard to get rid of. So after using any of these control methods, monitor your house and the surroundings to see if there are any signs of them regrouping and rebuilding their colony.

After applying pesticides on to their mounds, it is recommended that you monitor them for the next 3 to 5 days. In cases where the queen survives, they might rebuild and form a new mound in another place near your home. So watch out for new mounds and treat them accordingly. Best of luck!

List of Sources

Formica obscuripes, ITIS

Miner A., Formica Obscuripes, Western Thatching Ant, University of Michigan

Thatching Ants, Washington State University

Western Thatch Ant (Family Formicidae), University of Wisconsin-Milwaukee

Western Thatching Ant, Idaho Species, Department of Fish and Game