Let’s begin with a disclaimer. I don’t have any tips for surviving a visit from your mom’s wacko sister. I can only help with the six-legged variety of ant.
Well, sort of.
Nylanderia fulva was given the common name "tawny crazy ant" (TCA) because of their color (duh) and their frantic, seemingly psychotic movements. However, they’re probably saner than you if you discover they’ve settled down in your sedan and shorted out the electrical system.
In the late 1930s, a hapless swarm of accidental immigrants set out from a port in South America. Disembarking in Brownsville, Texas, they found the warmth and humidity of the Gulf Coast states appealing, so they stayed. Crazies haven’t spread as quickly as their cousin, the dreaded red imported fire ant (RIFA, Solenopsis invite), but their numbers are increasing.
Crazy ants don’t have stingers. They will bite but the pain is mild and short-lived. Nonetheless, they seem to be winning the ground war against all comers, not just our native ant species. RIFAs are a formidable opponent but crazies have a secret weapon; covering themselves with formic acid they neutralize the RIFA venom and live to fight on. TCAs are now found in more than 25 Lone Star counties, as well as the states of Louisiana, Mississippi, Georgia, and Florida, thanks largely to the unwitting assistance of people and our various modes of transportation, including vehicles.
What’s the appeal of a set of wheels? None of the reasons you signed on the dotted line. Crazy ants are cavity nesters, and while other members of their family like DIY projects, TCAs would much rather move into a pre-fab. Any protected space with an entryway roomy enough for a 1/8” torso will do. From that standpoint vehicles offer plenty of curb appeal.
If it were just one or two ant-y bodies, most likely you’d never even notice. An entire colony of a million or more is harder to miss, though, unless they’re hanging out in places you rarely see. Then one morning you turn the ignition switch, and… nothin’. So you pop the hood and find a whole heap of crazies strewn across the battery, alternator, and wiring. Or maybe your car stereo inexplicably stops working and you notice a stream of crazies pouring out of the CD player.
Scientists don’t fully understand the affinity between ants and electricity. Some hypothesize ants are attracted to the warmth generated by current in the wires. Others suggest they can’t resist the pull of a magnetic field. Or perhaps they’re just looking for something to eat and insulation looks tasty. What researchers do know is that ants will stop foraging when they detect the presence of an electric field and move toward the current. When an ant gets shocked it releases pheromones that alert other members of the colony. As new ants respond to the distress signal they are shocked in turn. Eventually there are so many dead and dying ants piling up that the electrical device in question malfunctions. This chain of events isn’t limited to vehicles—air conditioners, traffic lights, cell phones, laptops, transformers, and just about anything else you can think of that runs on electricity can become infested.
What can be done to prevent the invasion, or fend off the marauding horde once they’ve moved in?
I wish I had an easy answer. According to the Texas A&M urban entomology folks, crazies aren’t interested in most common ant baits. Over-the-counter insecticides are lethal but not enough to make a significant dent in the local population. My best advice is to seek help from a pest control professional who can create chemical “buffer zones” near vulnerable and valuable equipment, including the area where you normally park your car or truck.
While you’re at it, might as well schedule regular visits because the application wears off and the area will be breeched within two to three months.
NOTE: N. fulva was formerly known as the Raspberry crazy ant, named for Texas exterminator Tom Raspberry, who noticed back in 2002 that these ants were becoming more prevalent.