http://en.wikipedia.org/wiki/Rasberry_crazy_antAttraction to electrical equipment[edit]
It is unclear why colonies of Nylanderia fulva, like many species of ants, are attracted to electrical equipment.[3][12] They may sense the magnetic fields that surround wires conducting electric current, or they prefer the warmth produced by resistance to the currents in the wires. Some argue they simply are searching for food or an attractive place to nest.[13] Infestations of electrical equipment cause short circuits, sometimes because the ants chew through insulation. Overheating, corrosion, and mechanical failures also result from accumulations of dead ants and nest detritus in electrical devices.[14]
If an ant is electrocuted, it can release an alarm pheromone in dying, which causes other ants to rush over and search for attackers. If a large enough number of ants collects, it may short out systems.[15]