68 



adopt the parasite instead. The eñect of this is, of course, 

 the gradual impoverishment and extinction of the host colony. 

 There is no completely satisfactory explanation of the assassina- 

 tion of the Monomorium queen b}^ her own workers. Forel 

 thinks it may be due to the preference of the workers for a smaller 

 fertile female, just as Tetramorium workers prefer to bring 

 up males and females of Strongylognathus rather than their 

 own very large sexes. 



Anergates atratulus. 



During the sixty years that have elapsed since Schenck 

 discovered this extraordinary ant at Weilburg in May 1852, 

 numerous investigators have attempted to discover how the 

 female becomes permanently adopted in a colony of Tetramorium 

 cœspitum, but the problem has remained unsolved. 



It is evident that the newl}- fertilised female must leave her 

 nest and be accepted in some manner by a colony of T . cœspitum, 

 and, as neither queens, males, nor pupae of Tetramorium have 

 ever been found in a nest infested by Anergates, the host queen 

 must somehow be eliminated. 



The mating, owing to the absence of wings in the male, must 

 necessarily take place in the nest between brothers and sisters, 

 though Janet suggested that females might fl\' to other Anergates. 

 nests and be fertilised there, which seems improbable. Copula- 

 tion, both in natural and artificial nests, has been observed 

 by several people. Von Hagens saw a female leave the nest 

 and fly away, in August 1866, at Cleve ; and Wheeler in 

 June 1907 in Vaud, Switzerland, discovered a colony from which 

 female Anergates were fl3áng in great numbers. 



Adlerz, in 1886, records a few experiments with Anergates 

 ff males and strange Tetramorium colonies, in Sweden. He placed 

 several unfertiUsed females with a strange colony of Tetramorium, 

 The females moved about almost unnoticed among the ants. 

 Nearly the same results were obtained by placing unfertilised 

 females in a strange nest of Tetramorium provided with a queen 

 and brood of its own species. A number of larvae, pupœ, males 

 and females of Anergates were well received by a strange Tetra- 

 morium colony in an artificial nest. 



