Ant behavior: April 2010 Archives

I live in the Northern USA and wanted to know if Fire Ants will ever be a pest in my yard?

The Red Imported Fire ant, Solenopsis invicta, is an introduced pest in the United States from South America. There are also native fire ants (species of the genus Solenopsis) found in many parts of the world, including the United States. Although the Red Imported Fire ant is an introduced pest in many parts of the United States, Australia, and some islands, it is unlikely you will ever have the invasive Red Imported Fire ant in the northern US since they are not able to survive long winters with hard freezes. Red Imported Fire ants are considered "hot climate specialists". This means they are unlikely to survive in your North Dakota yard, but may still be able to survive in places with temperature controlled environments like greenhouses. This species has even made the list of "100 of the World's Worst invaders":

Solenopsis invicta - Red Imported Fire ant. Photo by Alex Wild (

Where in the US are Red Imported Fire ants found?

The Red Imported Fire ant is thought to have been first introduced in the US in the late 1930's in the port of Mobile, Alabama. They are considered a serious problem due to many factors that include their ability to spread rather rapidly, their painful sting, aggressive behavior, and damage to some agricultural crops and livestock. In the United States fire ants have spread from Alabama across the southern US and into isolated areas of California, which has resulted in quarantines of movement of some products like soil and plants to help stop the spread of these invasive ants. Although we are not certain how much further north and west they will spread, we do know that they will not be able to survive outside in areas with long, cold winters.

Distribution of Red Imported Fire ants in USA. Map from:

Why are they called Fire ants?

Well if you have ever been stung by a Fire ant you can answer this question. Fire ants get their common name from the fact that when they sting you it feels as though you have been touched by a red-hot flame. These ants bite onto you (or other enemies, intruders or prey) with their jaws and then inject a dose of venom with the sting on the rear end of their body. Their sting is not only painful, but for some people this can be a real problem since it can result in anaphylactic shock or even death in very extreme cases. Also most people develop an itchy, puss filled bump after being stung.

Fire ant stings USDA.jpg

Fire ant stings. Photo from:

How can I identify a Fire ant?

Telling fire ants apart from other ants can be difficult since they look like most ordinary red/brown ants, although AntWeb and a microscope will help. Two of the key signs are their behavior (they are very aggressive and sting readily) and mound-shaped nests. Each of these mounds can contain up to 300,000 individual ants.

Fire ant mound AlexWild.jpg

Fire ant mound. Photo by Alex Wild (

Although this species is considered an invasive pest in some areas like the United States and Australia, it is important to keep in mind that they are not all bad. In their native range of South America it is one of many important ants in the ecosystem. For more information on the Red Imported Fire Ant, check out this webpage which contains many informative links:

- Corrie Moreau & the AntAsk Team

Good evening,
I had accidentally spilled a drink on my laptop. I took it to "repair" but some keys remain slightly sticky. Recently my Macbook Pro was invaded by ants, and I figured they were after the remaining sugar residue. My bug-proof laptop is now riddled with bugs!

I was thinking I could use the ants to remove the remaining residue instead of squashing them. How quickly can they clean up sugar? Will they all leave once they are done, or will they try to make a nest in there (the laptop I am now typing on). These ants are pretty small so I think they can get under the keyboard keys. This is a much less expensive solution and doesn't require disassembly or very costly repairs.



I personally do not think that this is a good idea, but it depends, like you suggested, on what the intentions of the ants are.  It is possible that they are just going for the sugar, in which case they will quickly lose interest when they've eaten it all.  The length of time it will take them to do this depends on a lot of different factors, like how many ants are involved and how dried up and difficult to eat the sugar is - I would guess somewhere from a few hours to a few days.   

Although many ants are very good at cleaning up sugar, some of them are also quite good at chewing through plastic. Many of the species of ants that are often found living around humans seem to have a strange affinity for setting up nests in electrical equipment, and damage to the wiring almost invariably follows.  Two species of ants leap to mind that seem particularly prone to this behavior: the Raspberry Crazy Ant, and Monomorium destructor.  M. destructor, as the name suggests, is especially good at chewing through things, including electrical insulation.  Neither of these ants has been reported from Maryland-- the Raspberry Crazy Ant is mostly known from Texas, and M. destructor also tends to live in warmer areas (athough specimens have been collected in Tennessee and New York State).  You might consider browsing the Ants of Pennsylvania page, (likely candidates for your ants are Monomorium pharaonis and Tapinoma sessile).  

Even so, without knowing exactly which species of ant is infesting your computer, I would advise you to discourage the ants as quickly as possible.  As much as I am interested in ants, I would be nervous if they started showing interest in my laptop!  

Nylanderia sp

Monomorium destructor

- Jesse Czekanski-Moir & the AntAsk team

Good question Claude. As I am sure you know, ants, like most insects, don't do very well in the cold. But ants are always around in the spring when the weather warms up, so how are they surviving the winter? In general, the temperature underground is quite a bit higher than the air temperature. Ants take advantage of this by moving deeper underground in the winter. Some ant nests can be over 15 feet (4.57 meters) below ground level. They can also stay warm by grouping close together and sharing body heat.And ants in places where it is too cold to gather food during the winter may store food in their colonies and fill their crops (an extension of the gut used to store food and water) so that they do not starve.

So generally, ants hibernate during the winter, moving deep underground, grouping together, and generally limiting activity to conserve energy. Ants that live in particularly cold climates, like Leptothorax canadensis from Québec, Canada, and New England, USA, produce their own biological antifreeze so that the water in their bodies does not freeze. These ants are sometimes exposed to temperatures below -20° C (-4° F) but are able to survive even long cold winters by combining all of these methods for staying warm.

- Ben Rubin & the AntAsk Team

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