ANTS MYRMICIDES 165 



middeu, formed near by. M'Cook has witnessed and described 

 the process of stripping the seeds. 



Certain genera — e.g. Aphaemgaster, Pheidolc — exhibit great 

 disparity in the forms of the workers, some of which are of 

 size much superior to the others, and possess disproportionately 

 large heads ; these large individuals are found in the same nest 

 as the smaller forms. All the intermediate forms may frequently 

 be found, and at the same time, in the genus Aphaenogaster ; but 

 in Fheidole intermediates are of the utmost rarity. 



The genus Cremastogaster is remarkable on account of the 

 shape of the hind body and its articulation, which give the 

 abdomen the appearance of being put on upside down. This 

 mode of articulation may allow the Insect to threaten its enemies 



A B 



Fig. 71. — Cremastogaster tricolor, worker. A, witli abilomen e.\tendeJ ; B, uplifted. 



when they are in front of it ; but it is doubtful whether the 

 Cremastogaster possesses an effective sting. 



ii. The group Attini is distinguished by the presence of a 

 carina near the eye, by the antennae being inserted at a moderate 

 distance from one another, by the clypeus being prolonged back- 

 wards between them ; and by the absence of a sting. The 

 group is not represented in Europe, but in Tropical America the 

 ants belonging to it are amongst the most important of natural 

 objects. The species of the genus Atta (usually styled Oecodoma) 

 are the formidable leaf-cutting ants of America. They occur in 

 enormous colonies in certain places, and will in a short time 

 completely strip a tree of its leaves. As they appear to prefer 

 trees of a useful kind, especially those planted by man, their 

 ravages are often of the most serious nature. The natives, 

 feeling it hopeless to contend with these Insect hordes, only too 

 frequently abandon all attempts to cultivate the trees and 

 vegetables the Insects are fond of. Both Bates and Belt have 



