772 



CLASS IV. INSECTA. 



much greater extent by the genus Polyergus. Lasius is perhaps our 

 commonest British genus. 



Sub-fam. 2. Dolichoderinae. Like the previous family, but the 

 poison sac does not form a cushion and there is a rudimentary sting. 

 A small sub-family with few European representatives. Tapinoma, 

 British, but rare, attends the fights of other ants and carries off and 

 eats the vanquished. 



Sub-fam. 3. Myrmicinae. Pedicel of two nodes ; sting usually 

 present. This sub-family includes some thousand species. It is 

 often divided into four or even eight groups dependent on the shape 

 of the head and its component parts. Many genera do not construct 

 nests but live in the colonies of other ants, and some of these genera 

 have undergone marked changes of structure. About ten species 

 are British, the best known being Myrmica rubra. The harvesting ants 

 of the genus Aphaenogaster (Fig. 502) of Europe and America store up 



FIG. 503. Oecodoma cephalotes. South 

 America. A worker ; B female after 

 casting the wings. From Sharp. 



FIG. 504. Various forms of worker of Eciton 

 hamatum. Guatemala. From Sharp. 



granaries of grain and seeds in their homes. Atta (Oecodoma) is the 

 leaf -cutting ant of America (Fig. 503), and does much harm by denud- 

 ing trees of their foliage. The leaves are carried to the nests and 

 worked into balls, upon which the ants grow a certain fungus which 

 forms their staple diet. Pseudomyrma lives in the bull's-horn thorn 

 (an Acacia) and feeds on the secretions of certain glands in the leaves. 

 Cryptocerus (Fig. 369). 



Sub-fam. 4. Ponerinae. Pedicel of one node, abdomen elongated 

 and loosely jointed between the first and second normal segments. 

 A stridulating organ is often present between the loosely articulated 

 segments just mentioned. Sting present. The family has some four 

 hundred species, and is widely distributed but little known. Its col- 



