The response of isolated digging worker ants [Formica lemani bondroit andLasius niger (L.)] to tunnels

Abstract

1. In laboratory experimentsF. lemani andL. niger preferred to begin tunnels where moist sand met a solid surface. 2. Both species were, however, attracted to dig in artificial tunnels (made by pushing a wire into the sand). The effect of these was greater onF. lemani than onL. niger. 3. The tunnels whichL. niger dug, starting from an artificial tunnel, were usually at an angle to it; those ofF. lemani in line with it. 4. Where an ant was digging in two tunnels during a given period it was more likely to make two successive trips to the same tunnel than was expected. 5. About half the total of digging acts were not made at the end of the tunnel. The proportion of these «deficit» grabs did not differ between species. 6. The distance from the tunnel end at which «deficit» grabs were made was greater inL. niger than inF. lemani. 7. There was no evidence that this distance depended on the length of the tunnel. 8. The dispersion of grabs in a line at right-angles to the tunnel length was greater inL. niger than inF. lemani. 9. These differences may explain the differences in tunnel form between these species.