Electronic devices near Houston, Texas, are under attack by a species known as the "crazy rasberry ant" (Paratrechina species near pubens), which is thought to have arrived as a stowaway on a cargo ship in 2002. According to the Associated Press, the ants seem to be attracted to electrical equipment and have been "shorting out electrical boxes and messing up computers" wherever they go. This has raised concerns that the ants might cause serious damage to electrical equipment in sensitive locations like Houston's Hobby Airport and NASA's Johnson Space Center, as well as homes and businesses in the city. What do ants like about electronics?
No one really knows. Research has shown that some ant species are capable of detecting electromagnetic fields and may even use the Earth's magnetic field as a directional cue as they search for food or nest sites. Their attraction to man-made electrical devices may be an accidental evolutionary byproduct of this natural ability.
The ants may also be drawn to pieces of electrical equipment because they make great nests. Invasive species like the crazy rasberry ant are adapted to environments that are constantly changing, so they are always searching for new homes. In the wild, these ants might nest in small cavities beneath fallen leaves, inside branches, or at the base of palm fronds. Electrical switch boxes, gas meters, or your PC make ideal homes because they are dry and have small, easily defendable entrances.
When crazy rasberry ants invade an electrical box, they can't actually eat the equipment inside. Their jaws are not strong enough to cut through metal wires, but they can chew through the softer insulation around them, exposing the live wires and causing electrical shorts. (Other ant species, like leafcutter ants, are capable of cutting through thin metal wires, but they don't seem to be attracted to electronics.) When an ant is shocked or electrocuted, it releases a chemical alarm pheromone that attracts its nestmates, triggering a cascade that results in a buildup of dead worker ants that can cause further problems for electronics.
These ants are difficult to control because they are ready to abandon their homes and find new ones at a moment's notice, as when insecticides or poison baits are applied. Like many invasive ants, including some populations of the red imported fire ant (Solenopsis invicta), which is also thought to have arrived to the United States via cargo ship, crazy rasberry ant colonies contain multiple queens. As Houston-area exterminators have learned, this allows them to reproduce faster than single-queen species, and makes it hard to kill the entire colony.
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Explainer thanks Mark Deyrup of Archbold Biological Station and Andrew Suarez of the University of Illinois-Urbana-Champaign.