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Thief Ants

Summary: Thief ants are a big problem when they sneak indoors. Although they will definitely steal your food, their name actually comes from their favorite way to find food by stealing larvae or dead insects from other ant nests.

The thief ant is tough to eliminate due to its tiny size and its ability to nest in nearly inaccessible locations. Most pesticides will easily kill this stealthy invader on contact, but because they seldom make their presence known, you could have a full infestation before you know it.

Making a positive identification is important. Thief ants and Pharaoh ants look nearly identical, but the prescribed threatments are very different. The thief ant is usually brown or golden-yellow in coloration and it has antennae with ten segments. It is a tiny ant, measuring between 1/32 of an inch to 1/16 of


an inch. The biggest different between the two ants is their antennae. This will be a tough call unless you have a fairly high powered microscope. The Pharaoh ant has a 12-segmented antennae with a 3-segmented club, while the thief ant has a 10-segmented antennae with a 2-segmented club. Armed with that important information I'm sure you'll be a lost as the rest of us.

Thief ant queens lay eggs constantly. On any given day, a queen can lay between a few dozen to a few hundred eggs, the average being about 100. The eggs turn into larvae after 2-4 weeks, then, take about 3 weeks to pupate during warm temperatures. Larvae born in the fall will over-winter and emerge as pupae in the spring.

Did you know thief ants have a peculiar trait that few other insects have? After they die, they usually curl up into a ball. Find tiny little ants curled up in a ball and you've probably discovered thief ants. Learn something new everyday, don't you?

The thief ant derives its name from its behavior when searching for food. It will steal food from the nests of other ant species. If no food is available, it will even steal ant larvae. Besides young insects, thief ants also enjoy eating dead insects, greasy foods, seeds, dairy products, foods that are high in protein, and honeydew. They will feed on sweet foods if no other foods are available. They are sometimes referred to as “grease ants” because of their preference for foods containing high grease content.
Because they prefer to steal food rather than search for it, thief ants tend to build their nests near the nests of other ants in rotting wood, underneath bricks and stones, in tree cavities, and in crevices in the foundations of homes. Sometimes, though, they will build their homes indoors. These nests can be very hard to find. The best way to search for them is to find the trail of food thief ants leave behind that helps them find their way back to their nests. The most common places thief ants can be found are in cabinets, woodwork, trash bags, closets, and on windowsills. They will even nest in the hollows of window sills and door frames or being electrical wall outlets. Shocking!

Ant bait

How to Avoid Thief Ant Infestation:
• Keep your house clean on a regular basis. Thief ants and other pests are attracted to dirty places in which they can hide easily and obtain a food.
• Replace ripped screens in windows and doors immediately.
• Fix any crevices or cracks in the foundation or siding of your home.
• Clean up any spills of food or drinks quickly. Even if you are outside on your patio and accidentally spill some grease from your hamburger on the concrete, you should at least soak it up with a paper towel. Thief ants are attracted to greasy tastes, so they could scurry to the spill and then continue into your house.
• If you have shrubs or branches of trees touching your house, trim them down.

How to Handle Thief Ant Infestation:
• If you see thief ants scampering around, scoop them up with a soapy sponge.
• Caulk any holes by doors or windows to avoid letting more thief ants inside.
• Plug up the drains in your sinks and bathtubs at night.
• Make sure to put away food after consuming it, as thief ants can easily crawl into a bag of potato chips and go unnoticed because of their size.
• If the infestation is out of control, spraying an insecticide like Suspend SC directly on the ants or their nest should help.
• If thief ants are crawling inside hollow walls, drill some small holes into the walls. Then, apply a pesticide dust like Tempo 1% into the wall void.
• Use only ant baits with high protein content like Maxforce FC Ant Bait stations.

Make every effort to find the nest and eliminate it. Killing individual ants will help, but it will not fix the problem. If you cannot find their nest, call a professional exterminator to assist you, but be sure to quiz them on that segmented antennae stuff. You'll blow their minds!

Click here to watch my short video on how to control ants.

Ask Rick A Question


16 Jun 2009, 21:26
I did not know that they curled up when they die. I've seen it a 1000 times but thought it just meant 'now I won't be able to tell the difference between the two.'
chris b
18 Sep 2009, 13:08
We've noticed that squishing them on a white counter leaves a blue mark. Must be something in their body fluids.
18 Oct 2010, 00:58
We have thief ants and have a hard time getting rid of them. I use Raid ant and roach spray. Is this the best I can do or is there one better? Should I spray the outside of the house as well?
Ask the Exterminator
18 Oct 2010, 10:57
Read the article again. I've added some specific products you should be using. Click on the red, underlined links to the products.
09 Nov 2010, 12:19
We had a horrible infestation of thief ants this past summer. It was our first summer in this home and I had never even seen ants that small before! I found out that I could kill them with Lysol, which is relatively inexpensive compared to other products. Problem is, now that Autumn is here and visible signs of the ants are gone in our home, can anyone tell me what to look for to find nests? They (the ants) were found in nearly every room in our home, so I believe there are probably several dormant nests. If I hit the nests while they are dormant will it help to curb infestation next spring?
Ask the Exterminator
09 Nov 2010, 14:44
I always get confused when someone asks a question like this when the answer is in the article on this page. Jo, you need to follow the treatment suggestions made in the article.
07 Jul 2011, 20:56
Thank you so much for the information! I am renting in a small town that doesn't have any listings for an exterminator less than 40 miles away so every bit helps! At least now I know where to start.
22 Jul 2011, 12:33
Excellent article: informative and practical. Thank you very much!
dave carpy
09 Aug 2011, 20:51
These ants will actually take over a colony of fire ants by attacking them and stealing their eggs.
Amazing. I watched the process one afternoon, and was fascinated that this tiny ant could wipe out the dreaded fire ant.
12 Aug 2011, 22:42
we came upon your site while searching to find what species the ants are that we have found in our cupboards. they are the smallest we have ever seen! had never heard of the thief ant before. we are going to try to find the products you recommended at the stores tomorrow as we want to get at them asap! if we can't purchase locally we will be ordering. thanks for your helpful article.
26 Sep 2011, 19:59
Thank you for this information. I think I've now identified the ants in my apartment. I am going to check on the products you've suggested to see if they are safe to use around pets. Thanks again!
Ken Brennen
10 Aug 2012, 14:13
I do have a magnifier powerful enough to check out the antennae but the trouble was holding one still. Finally I came down on one with the sticky side of a 2 inch piece of Scotch tape, then folded the tape over to hold the ant from both sides. Without folding the tape over the ant was able to quickly get free and walk away.
13 Aug 2012, 12:38
I have positively ID the ants in my cupboard as thief ants (using a high powered microscope) and have been using the Maxforce FC ant bait stations you suggested but they won't go in them. I even made a trail into the traps with the veg. oil they love so much. They seemed to be going in but are still alive. How long will it take to kill the colony with the bait? And do you have any other suggestions to get them to "take the bait?"
Ask the Exterminator
17 Aug 2012, 15:00
Read the label: 2. Indoor Use: For normal infestations, you should use 3 MAXFORCE® FC Professional Insect Control® Ant Bait Stations in an average size room. For heavier infestations, you will need additional bait stations in each room. If infestation persists beyond two weeks, replace all bait stations where the bait has been completely consumed and relocate bait stations that show no evidence of ant
24 Jul 2013, 11:00
I did read the label and I used 3 stations in the pantry where they were infesting. They wouldn't take the bait. Any other suggestions?
Ask the Exterminator
24 Jul 2013, 11:14
You cannot use bait in conjunction with any other pesticide. Baits are attractants, while sprays are aerosols are repellents. The two don't mix. This might be the problem.
30 Aug 2013, 17:09
Here is what I did. So far its been working. I took some fancy feast cat food and mixed boric acid into it. I put a table spoon of it and put it on a piece of paper and left it on my counter. Within minutes it was covered with ants. Every day I watched it shrink but as the days went by less and less ants were there. Now on the outside I cant leave the bait in the open. So I took a sealable disposable container and cut small holes around the edges so the ants could come in. I put the ant bait in and put a something heavy on top. This is so if a cat smelled it they couldn’t open the container.
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