A FORMICA SLAVE-MAKER RAIDING THE NEST 
OF A MYRMICINE ANT 
By W. L. Brown, Jr. 
Museum of Comparative Zoology 
Slave-making Formica of the sanguinea group normally 
raid the nests of Formica of the fusca, pallidefulva or 
neogagates groups to obtain pupae to be reared into slavery. 
Occasionally, F. sanguinea group species have been seen 
to raid other formicine genera, especially Lasius, and 
Wheeler (1905, Bull. Amer. Mus. Nat. Hist. 21: 11) even 
recorded a raid on a nest of Myrmica (subfamily Myrmi- 
cinae) species that he watched in Connecticut. Raids by 
Formica on myrmicines apparently are rare occurrences, 
so the circumstances of such a raid are worth reporting. 
On August 22, 1958, at Brown County State Park, In- 
diana, I witnessed a raid by Formica subintegra Emery on 
a nest of the much smaller myrmicine ant Aphaenogaster 
rudis Emery. The nest entrances of the raiders and the 
victims were simple holes situated only about one meter 
apart in the bare clay soil of a hilltop campground, shaded 
by hickories and a few oaks. The raid was first noticed at 
about 3 P. M., about 3 hours after a heavy rain had ceased. 
The sky was partly cloudy, and the air temperature stood 
at about 70 °F. 
Most of the visible activity occurred in and around the 
entrance to the A. rudis nest. Six dead or badly maimed 
rudis workers lay near the entrance, accompanied by one 
crippled F. subintegra worker. One subintegra worker 
grappled with a rudis worker and put it out of action while 
I watched. At irregular intervals, subintegra workers em- 
erged, most of them carrying a pupa or a dead or struggling 
worker of A. rudis , with which they returned directly to 
their own nest and entered there. Two subintegra workers 
carried folded-up workers of their own species; when dis- 
turbed, these workrs dropped their burdens, which proved 
to be active and apparently unhurt. 
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