274 



HENRY C. MCCOOK. 



by the farmers on their way over the mountain to the town. There 

 is no marked impression upon the surftice as of a worn or prepared 

 road, but the boundaries of the avenue are constant, the ants in- 

 variably traversing the same general limits, which vary from one to 

 three inches in width Leaving the avenue at the foot of the young 

 oak, the column stretches its double line along the trunk and is dis- 

 tributed among the principal branches. A considerable portion leads 

 oflp upon one of the lower limbs which overhangs the stone fence. I 

 mount this wall, and at once have the key to the movements of the 

 promenaders upon the avenue beneath. 



Galls.— At various points along the bough and its branches vast 

 numbers of aphides are clustered. Many of these are fastened upon 

 the bark in the usual manner, the head depressed, the abdomen ele- 

 vated. Others are clustered about 

 small oak galls, some white, mar- 

 bled with black, some of a pink- 

 EFf/ / J \ brown color with rings, some of a 

 brownish hue. These galls eon- 

 tain a quantity ol' minute black 

 powder, a number of very small 

 white oval eggs (?), and a grub 

 Fig. S.— Aphis and galls. (1), a])bis, three-tenths of an inch long, with 

 back view; (2), same, side view; (3), twelve rings, head marked with 

 palls. K^hh, Lachnus Allegheniensis. ^^,^^,,^ .^ ^^,^^^ ^.j^^ ^^ ^j^^ ^^^j^^ 



and three pairs of feet. The ants seemed to be feeding upon these 

 galls; they at least fed upon the juices of several of the grubs which 

 were crushed with the point of a knife, while removing the galls. 

 These, however, are but secondary objects of attention. The aphides, 

 black insects, with brownish thorax and head, are the centres of 

 principal interest. Here is one whose abdomen is elevated at an 

 angle of about -45°. Upon the apex is shining a tiny globule of 

 transparent liquid. It is greedily lapped by the attendant ant, who 

 all the while, with alternate strokes of the antennae, gently eujbraccs 

 or pats the insect. Again and again in rapid succession the sweet 

 secretion, (the honey-dew of popular speech) gathers in drops, and 

 is removed by the ants, several of whom have in turn enjoyed the 

 refection. At last the aphis, one of mature size, leaves its position 

 and moves along the limb towards the trunk. It is passed by groups 

 and individuals of ants all of whom greet it with the antenna) as 

 though testing its disposition or resources, and at once allow it to 



