1920] Shapley — Note on Pterergates in the California Harvester Ant 73 



pterergates in New York from a colony of Myrmica scabrinodis 

 var.; Keys found one of the same species in England (figured in 

 Donisthorpe's British Ants, p. 41). Wheeler has also taken a large 

 worker with vestigial wings from a colony of Cryptocerus aztecus in 

 Mexico, and Bondroit found at Landelies in Belgium one pterer- 

 gate of the species Lasius flaviis. 



One of the most common ants in Pasadena at the present time 

 is the large red harvester, Pogonomyrmex califonucus Buckley, but 

 apparently it is being exterminated by Iridomyrmex humilis Mayr, 

 the rapidly spreading Argentine ant. From one of the small 

 embattled nests of P. ccdifornicus which has been under observa- 

 tion since March, 1919, 1 sent a few specimens to Professor Wheeler, 

 who called my attention to the presence of three pterergates. 

 Further investigation has shown that of all the workers of this nest 



Fig. 1. Vestigial anterior wing of a worker of Pogonomyrmex californicus 

 Buckley. 



seen during 1919 one-half has vestigial wings, varying in degree of 

 development from small chitinous nodules on the mesothorax to 

 membranous structures one to two millimeters in length. Except 

 for these organs representing wings, there is no conspicuous differ- 

 ence in thoracic structure, or otherwise, between the pterergates 

 and the remainder of the workers. 



The vestiges observed in all six of the pterergates mentioned in 

 the first paragraph are on the mesothorax, and indicate the abnor- 

 mal development of anterior wings. There is also but a single pair 

 of vestiges for sixteen of the pterergates of P. ccdifornicus so far 

 examined. 



One individual from this nest, however, is unique, not only in 

 having vestiges both of anterior and of posterior wings, but also 

 in possessing one anterior wing that is membranous and veined. 

 A diagram of the venation of this most developed wing, which 

 resembles more closely that of a normal hind wing, is given in 



