Ants get a transforming charge.

Ants get a transforming charge

Red fire ants, infamous for their nasty bites, have gained added notoriety for their habit of invading outdoor electrical equipment such as traffic signal control boxes, household electric meters and airport runway lights. The insects especially enjoy gathering around tiny electrical switches called relays, where they congregate by the hundreds, disrupting current flow and permanently damaging surrounding circuitry.

While the electricity itself rarely kills the ants, their affinity for these devices apparently overwhelms their usual drive to eat and drink, leaving masses of the insects dead of starvation and thirst. But an incomplete understanding of exactly what the ants really like about these highly charged environs has left engineers and entomologists uncertain how to deal with the problem.

Experiments at Texas A&M University in College Station now confirm that electrical fields are the draw. The researchers ruled out other candidate attractants, including magnetic fields, vibration and the ozone generated by such devices.

Scientists still don't know why ants find electrical fields so attractive. But since electrical relays by definition generate these fields, the simplest anti-ant strategy amounts to sealing the affected components in plastic boxes and applying insecticides around surrounding wires, concludes William P. MacKay, who led the study. For those inclined toward a more punitive approach, he adds, preliminary experiments indicate that circuits adapted to deliver a whopping 550 volts across relay points neatly eliminate ants caught lingering in the vicinity.