142 . Psyche [Oct.-Dec. 



tember 10, suggested that the queen inight have been absent for 

 some time before the earlier date.^ 



Of two diabolica nests taken September 14, one contained approx- 

 imately 150 workers and 250 males, though the colony must have 

 numbered fully a thousand during its prime. This nest had no 

 queen, but in the other one killed the same day, along with 40 

 workers and 60 males, w^as a single virgin female, the last of a 

 considerable number that the colony had produced. 



Onr observations on V. arctica and diabolica, though fragmen- 

 tary, seem to justify the following conclusions : 



1. The nest-founding queen of Y. diabolica, like that of the 

 European media, is rather short-lived, completing oviposition and 

 perishing rather early in the season, probably not later than the 

 middle or early part of August, at least during favorable summers. 



2. There are some indications that the diabolica queen, like 

 the crabro queen, has a tendency to desert her nest in an incipient 

 stage and found another. 



3. V. arctica is a permanent social parasite in the nest of dia- 

 boUca, and her brood, consisting exclusively of males and fertile 

 females, is reared by the diabolica workers. 



4. The over-wintering queen of arctica, like that of austriaca, 

 probably appears late in spring, at a time when the nests of the 

 host-species are already established and contain enough workers 

 to nurse her brood. 



> In taking this nest at dusk the junior author failed to capture about a 

 dozen workers which were still flying about, and which finally settled on the 

 tree from which the nest had been cut. Deprived of their habitation, and 

 even of the branch which supported it, these few workers were huddled 

 together the next evening at a place remote from the original position of 

 the nest. Closer observation revealed that they had already attached bits 

 of newly-made paper to the bark of the tree. It was about this paper that 

 the workers were congregated. By the end of the second day the wasps had 

 suspended a single cell from a strong filament of paper after the manner of 

 a queen in founding her nest in the spring, and in a few more days the 

 structure had begun to assume the proportions of a normal nest. On Sep- 

 tember 10 it was about the size of a hen's egg and there were still two or 

 three workers defending it (Fig. 3). Six days later this nest was found 

 torn open, apparently by a predator, perhaps a bird, which had robbed it of 

 whatever it might have contained, thereby preventing further observation. 



The construction of nests by workers of European species of wasps has 

 been observed by several authors, notably Janet (1903), who describes three 

 new nests built successively by workers of the same colony. Other accounts 

 are given by Ormerod (1859), Stone (1860), von Siebold (1871), Kristof (1878) 

 and Marchal (1896). 



