48 
Psyche 
[March 
FURTHER NOTES ON THE HABITS OF 
HARPAGOXENUS AMERICANUS } 
By Wm. S. Creighton 
The social parasitism of Harpagoxenus americanus, Em., has 
been discussed by Sturtevant in a paper published in 1927. 
This investigator found that the behavior of an artificially 
dealated Harpagoxenus female placed in a nest of Leptothorax 
curvispinosus , one of its natural hosts, agrees in all essential 
respects with that of the females of the sanguinea group in 
Formica. The strange queen is at once attacked by the Lepto- 
thorax workers but she eventually cripples most of her assail- 
ants, disorganizes the remainder and takes possession of 
the brood. 
During the summer of 1928 I was stationed on Naushon 
Island (Woods Hole), Mass., the only place in New England 
where Harpagoxenus is known to be at all plentiful. I was for- 
tunate in securing several mixed colonies and in rearing 
from one of these numerous males and females. There was 
consequently abundant opportunity to repeat the experi- 
ment previously made by Sturtevant. Our results differ only 
in minor details which may be due to the fact that he used 
L. curvispinosus as the host while I employed L. longispinosus. 
Sturtevant introduced his dealated Harpagoxenus female into 
a nest containing seventy workers of L. curvispinosus and 
secured good results. I found it necessary to strip the host 
nest of all but about fifteen workers in order to prevent the 
death of the Harpagoxenus queen. If a larger number of lon- 
gispinosus workers were present they invariably pulled down 
and killed the intruder by force of numbers. The worker of 
longispinosus is slightly larger than that of curvispinosus and 
its greater size may give it an advantage in attacking the 
invader. It was also necessary to wait for one hour after 
deflating the Harpagoxenus female before placing it in the 
nest of the host. If placed therein immediately after deala- 
iContributions from the Entomological Laboratory of the Bussey 
Institution, Harvard University, No. 311. 
