Wasps, Bees, and Ants 



541 



to quantity and time. If the regulation by the workers of the kind and 

 quantity of food given the larva is the cause or one of several influencing 

 factors in determining the caste or kind of individual into which the larva 

 shall develop, as is believed by most 

 students of social insects, then the 

 unmanipulated food of the Ponerine 

 larvae and the inequality of its con- 

 trol as to quantity and time of feed- 

 ing may explain how it is that the 

 caste distinctions are so much less 

 marked in this primitive ant family 

 than in the Myrmicidae and Campo- 

 notidae, where, as we shall see, the 

 character and amount of the food 

 given the larvae is carefully controlled 

 by the workers. 



FIG. 744. A Ponerine 



Leptogenys 



The family Myrmicidae includes a ^ ngata , (A fter Wheeler; 'enlarged.) 

 large number of our most interesting 



ants; almost all are stingers, and all are readily distinguished from members 

 of either of the other families by having the basal two abdominal segments 

 knot-like, and forming the peduncle. Some of the Myrmicids are well 

 known because of their abundance, wide distribution, and troublesome ten- 

 dency to invade our houses, like the common little red ant, Monomorium 

 pharaonis, while others are familiar through the accounts which have been 

 written by various authors of their specialized 

 habits. Among the latter are . the harvesting or 

 agricultural ants (Pogonomyrmex) , a single species 

 of which, the large harvester of Texas, P. barbaius 

 var. molijaciens, has had a three-hundred-page 

 book devoted to it, and the fierce marauding ants 

 of the genera Eciton and Atta best known through 

 certain famous tropic kinds, but represented in this 

 country by several thoroughly interesting and char- 

 acteristic species. 



Nine species of harvesters (Pogonomyrmex) (Fig. 

 745) occur in' this country (in the southern, south- 

 western, and Pacific coast states) all (except one 

 small retiring species) as far as known forming small or large communities 

 in nests partly underground and partly heaped up in conspicuous mounds 

 (Figs. 746 and 747) in open, sunny, and usually grassy places. They live 

 specially abundantly in the great western plains and indeed in nearly desert 

 regions. Into the nest they bring great stores of seeds and grains, gathered 



FIG. 745. An agricultural- 

 ant worker, Pogonomyr- 

 mex imberbicolus. (After 

 Wheeler; much enlarged.) 



