VII PAETHENOGENESIS 249 



part of the book is devoted to an account of the 

 parthenogenesis observable in the wasp Polistes. 

 Leuckart first recorded, in his work already mentioned, 

 that the workers of wasps, ants, hornets, and humble 

 bees lay eggs, which in one case he followed to the 

 development of a larva, of which he was not able 

 to determine the sex. Siebold determined to study 

 a species of Polistes common in and around Munich, 

 which he identifies with much care, and after reference 

 to specimens and authorities from many lands, as 

 Polistes gallica var. diadema Latreille. He gives a 

 minute description of the characters of the females and 

 males ; the two kinds of the former (queens and 

 workers) being only distinguishable by size — the 

 workers in all external characters as well as in their 

 generative organs being merely smaller queens, and 

 fully capable of copulation and impregnation. In the 

 beginning of May, in Munich, the Polistes queens 

 which were born in the previous summer and impreg- 

 nated then, commence each to build a nest. No queen 

 who built in the former year survives to build a second 

 time, and the young queens never make use of the old 

 nests. The Polistes are very particular in choosing a 

 warm sunshiny spot, sheltered from wind and rain, 

 and as such spots are not too common, a new nest is 

 often begun near the weathered remains of an old one. 

 Walls and trunks of trees, often at such a height as 

 not to be easily reached, are the sites chosen. A\ hen 

 the queen has constructed fifteen or twenty cells, she 

 lays eggs in them, and is very hard-worked in guard- 

 ing her nest and in providing food for the larvae as 



