The Recent Introduction Of Raspberry Ants To Texas

It's been years since the red imported fire ant first made an appearance, and the situation is still not entirely under control. Now a new species has arrived. They are known as `crazy raspberry ants' and they are concentrated in 8 counties in and around Houston. The ants have been in Texas since 2002, but their growth has exploded in the past year, with three more counties added to the list of those already infested.  

The ants are called "crazy" because they scurry about in a seemingly random pattern, and they're called `raspberry' not for their appearance, but for Tom Raspberry, the pest controller who first discovered them six years ago. 

Unlike the much-reviled fire ant, the crazy raspberry ants don't sting and their bite is relatively inoffensive. But this doesn't mean these ants don't cause problems. What they lack in bite, they make up for in sheer numbers. When crazy raspberry ants infest a property, they tend do so in spectacular fashion.  An infestation can number in the billions of ants, and once an infestation is established, property owners find them extremely difficult to control.

Usually the size of an ant colony is held in check by other colonies of the same species--all of them competing for the same resources. If an ant from one colony encounters an ant from another, they will start a fight, often to the death. Colonies may also mount massive raids against one another. No so with the Raspberry ants.  Different colonies of raspberry ants are not hostile to each other, but instead treat one another as if they were nest mates. This means that Raspberry ants throughout Texas are just on big happy family, creating what is in effect a single, enormous, statewide "super colony." Without checks from other members of their species and without any natural predators, the Raspberry ants can achieve an almost total environmental control.

When the ants enter homes or industrial sites, they're often drawn to the warm buzz of electrical equipment. Their diminutive size, about 3 mm, means that when teeming masses of them crawl across a circuit board, they can fall between the spaces of electrical elements, closing the loop and shorting out connections. They have damaged pumping stations, fire alarms, and personal computers. They've even made an unsuccessful play for NASA's Johnson space center.

It's clear that the crazy raspberry ants are having an impact on the environment. They kill many other insects, including fire ants and snakes, which has earned them some friends. However, they have also been reported to overwhelm newly hatched birds and small mammals. 

Still, much more research needs to be done to determine the lasting environmental consequences of their explosion. One of the basic problems of invasive species is that other species in the regions have not evolved to deal with them. So they can severely affect the numbers of resident species that live in the area. Still the ants seem to have fallen into a regulatory hole. 

So what's being done to control these ants? Bryan Black from the Texas Department of Agriculture says that these ants can be controlled using Termidor, a pesticide used to control termites.  Recently, at the request of Tom Raspberry, the TDA has expanded labeling of this product to allow pest controllers to use it in significantly larger quantities when combating raspberry ants.