164 



HYMENOPTERA 



individuals weigh 1 gramme, and it is probable that a nest 

 may include millions of specimens. 



The genus Ajihacnogaster^ and its imnrediate allies include the 

 harvesting ants of Europe and North America : they form subter- 

 ranean nests consisting of iso- 

 lated chambers connected by 

 galleries ; some of the chambers 

 are used as store -houses or 

 granaries, considerable quantities 

 of corn, grass, and other seeds 

 being placed in them. A. 

 structor and A. larharus have 

 been observed to do this in 

 Southern Europe by Lespes, 

 Moggridge, and others. 



In the deserts about Algeria 

 and Tunis a harvesting ant, 

 A2)haenogaMer {Messor) aren- 

 arius, is an important creature : 

 its subterranean dwellings are 

 very extensive, and are placed 

 at a depth of several feet from 

 the surface. Entrance to these 

 dwellings is obtained by small 

 holes, which are the orifices of 

 galleries many feet in length : 

 D, small t]^g holes are surrounded by 

 pellets of sand projecting some- 

 what above the general surface, and consequently making the 

 places conspicuous. The subterranean works occupy an area of 

 fifty or a hundred square yards excavated at a depth of three to 

 six feet. In these immense nests there exists a form of worker, 

 of very small size, that never comes to the surface." 



Pogonomyrmex barbatus and other species have been observed 

 to do harvesting in North America. After the workers of P. 

 barbatus have taken the seeds into the nest they separate the 

 husks and carry them out, depositing them on a heap or kitchen- 



' Until recently this genus wa-s generally known as Atta, but this name is now 

 applied to tlie leaf-cutting ants, that were formerly called Oecodoma. 

 2 Forel, Bull. Soc. Vaudoisc, xxx. pp. 29-30, 1894. 



Fn;. 70. — ApluienorjnMer (Messor) harbarus. 

 Algeria. A, male ; B, winged female ; 

 C, large worker or soldier 

 worker, x iS. 



