I20 — 



leaves, went first to the muslin sides of the cage and afterwards to 

 the wheat plants. One of these remained for two weeks, alive, on 

 one of the plants, but I could not see that she produced young. 

 While these transitions were certainly made between the tree and 

 grain plants, nature apparently chose to accomplish it only by her 

 own methods, and would brook no interference or human assistance. 



Early in March of the present year (1893) I placed in the 

 insectary a couple of small seedling apple trees and to these bound 

 twigs from the orchard, thickly stuck with eggs of this Aphis mali. 

 In the same bench, about twenty feet away, wheat was sown, while 

 some corn was planted in the intervening space. A pot containing 

 a strawberry plant infested by another species of Aphis, and which 

 were attended by ants, Lasiiis fltwiis^ had previously been placed 

 on this bench. With the hatching of the iiiali a large portion of 

 the ants abandoned their wards on the strawberry and gave their 

 attention to the new ones on the apple. The strawberry was then 

 removed, but they still clung to their new found friends. As the 

 population on the apple increased the ants distributed the apterous 

 females to plants of Poa^ Sftaria, and Ambrosia arte/nisitcfoiid, 

 but especially to the wheat, carrying them l)y the corn to the 

 wheat beyond, which soon became overrun with aphis. Later, 

 they began to colonize their wards on the corn, but this seemed to 

 be less desirable than either the wheat or grass. Winged ///<?// left 

 the apple unaided, and after taking up their position on the wheat 

 began their labor of reproduction. On this wheat being uprooted 

 the indefatigable ants removed them to a few wheat plants still 

 farther away from the apple. 



The species also lives over winter in the wheat fields, at least 

 during mild winters, and I have found females reproducing every 

 month of the year. Here, in the west, when the young wheat 

 comes uj) in September and October, the winged females appear 

 on the plants and give birth to their young, and these crawling 

 downward attach themselves to the stems just below the surface 

 of the ground, or often on the roots themselves. Here they go 

 on reproducing when the temperature is favorable, the adults being 

 apterous, so far as observed by me, until spring, when they ascend 

 to the foliage, the adults being after this both winged and wing- 

 less. On the stems and roots below the surface of the ground, 

 they are of a greenish color tinged with a reddish brown, espec- 

 ially ])osteriorly, the full grown individuals often being wholly of 

 a dark brown. It is during autumn that they do their greatest 

 injury to wheat by sucking the juices from the young plants, often. 



