The dark guest ant (Anergates atratulus) is peculiar in that it takes over queenless colonies of Tetramorium ants, killing all the reproductive individuals in the colony.
Helsinki University ant specialists Riitta Savolainen and Kari Vepsäläinen made the find in late June on the Tvärminne dunes on mainland Finland’s southernmost Hanko peninsula.
“This was the 44th Tetramorium ant nest that we checked this year. There were many dark guest ant queens as well as a number of males,” Savolainen says.
Another researcher found one Anergates female in a trap on the dunes in early July.
The only other sighting of dark guest ants was in 1981 on Joskär, an island near Hanko.