1913] PemphigincB Attacking Populus 1 71 Colorado. 489 



Length of body, 1.75 to 2.00; wing, 2.60; antenna (figure 5), .60; 

 sensoria: — joint 3, from 4 to 7, but nearly always 5; joint 3, 2 to 4, but 

 nearly always 3; joints 5 and 6 with permanent sensoria only; joint 3, 

 slightly longer than 6, but not as long as joint 6 with the spur included; 

 joints 4 and 5 about equal, pennanent sensoria ciliated; sensoria on 

 short transverse lobes or ridges which do not extend nearly around the 

 antennal joints; spur on joint 3 rather weak. 



Sexuales. 



The alate sexupara begins giving birth to the sexual forms soon 

 after leaving the galls. Those that escaped from the galls collected 

 August 31st, had given birth to many males and oviparous females 

 in the breeding cage September 1st. The females are greenish in color 

 and measure about .90 in length; the males are pale yellow in color and 

 measure about .60 in length; neither have beaks with which to take 

 food; about 4 to 5 of each are bom from one female. 



The fact that this species is on the cotton woods from the 

 time of formation of the stem mother gall early in the summer 

 until the developement of the sexupara, it seems strongly proba- 

 ble that this species has no alternate host plant. The sexuales 

 must be deposited upon the cottonwood or the stem mother 

 could hardly be upon the leaves of these trees early in the spring, 



SUMMARY OF LIFE HISTORY. 



From all the data that we have been able to gather to the 

 present time it seems probable that the life history of this species 

 is about as follows: 



The fundatrix hatches upon the cottonwood in the spring 

 from eggs deposited upon these trees the previous fall. These 

 stem mothers locate between the midrib and the margin of one 

 of the early developing leaves and produce almond shaped galls 

 similar to those that are produced on the terminal leaves, by 

 their descendants, later in the season. From this stem-mother 

 gall, the young escape almost as soon as born and lo.cate on the 

 tender new leaves, as did their mother, between the margin 

 and midrib, each louse being solitary and producing an almond 

 shaped gall. Apparently the lice of this second generation 

 all become winged at first, it is certain that many do, and leave 

 the galls, while a portion, especially of the later lice that are 

 born, remain apterous, stay in the galls, and give birth to a third 

 generation. These young, like the young from the stem mother, 

 also migrate to the new leaves to continue the production of 

 galls, each of which harbors but one louse at first, but a portion 

 of the young of this brood remain with the mother in the gall 



