Appearance
Leafcutter ants are fairly large ants. The actual size is between three and seven millimeters. You'll definitively be able to tell them apart from normal ants because of their size. As for the color of the Leafcutter ants, they are usually a solid or dark red.
Location
Leafcutter ants are located in various parts of the world such as Central America, South America, and even parts of the southern United States. Parts of south Texas are infested with these ants; I know from personal experience. If you're located in a colder environment then it is unlikely that you will have to deal with Leafcutter ants because they prefer warm climates.
What They Do
Leafcutter ants can wreak havoc on your garden, trees, shrubs; etc. These ants will basically strip an entire plant of all of its leaves, which can seriously damage it with time. Your plants will regrow their leaves, but the Leafcutter ants may return and strip them all over again. This can cause your plants to eventually go into shock, which could kill them.
When They Attack
Leafcutter ants normally strip plants of their leaves at night. So in the morning, you will wake up to a small nightmare. If it's early in the morning then you may notice a few ants wandering away with the remnants of your plants.
Or you may actually hear faint rustling noises, which are the sounds of the Leafcutter ants tearing apart vegetation. It's kind of creepy. You may also notice small paths that lead away from your plants to the Leafcutter ant mound(s).
Also, you might see bits and pieces of leaves that have been stripped from nearby vegetation along these paths. The mounds will also have the remnants of leaves and other plants scattered around them.
How to Eliminate The Leafcutter Ants
Leafcutter ants are very difficult to destroy. Even dumping diesel or gasoline on the ant mounds will not kill them. But it might damage them a bit, and destroy all the plant life that is around the mounds(not necessarily a good thing). Pesticides have a limited impact on these ants as well.
It seems as if Leafcutter ants are resistant to almost everything, and the stuff that they're not resistant to really doesn't cause them that much damage. And forget about placing a barrier between your plants and the Leafcutter ants because they will simply find a way around your barrier.
Leafcutter ants are extremely persistent, among other things. The only good news for you is that when there is a plentiful amount of rain, the Leafcutter ants will usually become less of a nuisance because there will be ample vegetation for them to choose from. But if there's a drought in progress then don't be surprised if you wake up one morning to find all of your vegetation stripped away.
Leafcutter ants are the ultimate pest. These ants are stubborn, unpredictable, and very difficult to kill. If you ever have to deal with Leafcutter ants, be prepared for a tough fight. It may just be one that you cannot win.