WOOD ANTS ORIENT TO MAGNETIC-FIELDS

We report here, the first evidence that ants Formica rufa L. exhibit a magnetic compass response. For a period of seven days, foragers were trained to visit a food source accessed through a choice chamber situa ted inside a solenoid. When all other orientational cues were eliminat ed, the distribution of ants entering the choice chamber was significa ntly heterogeneous; a majority visiting the previous location of the f ood source. Energization of the solenoid, causing a 90 degrees rotatio n of the magnetic field, resulted in a significant proportion of ants orienting to the altered field.