Items you will need
Soap and water
Have you tried to get rid of ants to no avail? You may be using the wrong sort of bait or trap. Thief ants, more commonly known as grease ants, can get into almost any container because of their small size. They eat almost anything, but are particularly attracted to greasy foods such as peanut butter, meat and cheese. In other words, if you have a meat lovers pizza lying around for long enough, this kind of ant would have a feast. You need to identify this ant correctly in order to get the right kind of bait, so learn how to differentiate these ants from other common household ants.
Find the ant trail to establish in which direction they are traveling and where their food source is. It's important to find the food source and eliminate it, because if you don't do this, they'll just rebuild the trail again. Sometimes there are several food sources, that's why it's important to clean the area thoroughly before you attempt to get rid of the ant problem. Wipe all surfaces down with a bleach and water spray to make sure you eliminate all traces of grease.
Spray the ant trail with ant spray. If the ants curl up into a ball when they die, they are grease ants. Make sure you correctly identify them so that you set the right kinds of traps. After you have sprayed the trail, clean up any dead ants with paper towels and soapy water. Make sure you get rid of any traces of food along the trail. This is very important! Take out the trash and put all food into a refrigerator or other climate controlled place where the ants can't smell it.
Place the ant traps along the place where you saw the trail. Ants from the colony will attempt to scout out the scent from their predecessors or any other food, so make sure you make this impossible for them. They should smell the bait in the traps instead and head straight for them.
Mop and sweep all floor surfaces to get rid of crumbs and keep all counters cleaned to keep the ants from coming back. If you find that you still have scouts coming to look for food, you may need to call an exterminator to get rid of the ants because they are evidently still finding food somewhere. Usually, eliminating the food source forces them to look elsewhere, or die off. However, they may have sufficient stores to wait until you get sloppy again and then the problem will reoccur.
The best tip you can have to get rid of grease ants is to keep your environment clean!