Februarj-, '14] PARKER: SUGAR-BEET ROOT-LOUSE 139 



Sexual activity is not shown mitil the fourth molt after which the males 

 crawl blindly about attempting to copulate with any female they can find. 

 In from seven to tAvelve days after birth the female deposits a single, 

 pale yellow egg and in a short time dies. Sometimes death occurs 

 before the egg is extruded in which case the walls of the abdomen grad- 

 ually shrink away finally leaving the egg exposed. Normally the 

 female secretes a mass of bluish, white threads in which the egg rests 

 after deposition. 



Gillette has also reported finding the true sexes upon cottonwood in 

 Colorado.^ 



Eggs 



Eggs deposited by the sexual females remain in the crevices of 

 the bark until the following spring, without change. By April 15, 

 many of the eggs were turning darker in color and showed the eyes and 

 a dark spot in the abdomen of the embryo. Hatching was first observed 

 out of doors at Bozeman, May 3. The shell split near the head and by 

 contractions of the body the young louse slowly forced its way out of 

 the shell. 



Stem Mother — Fundatrix of European Writers 



The young lice hatching from the eggs crawl up the trees and cluster 

 upon the expanding buds. As soon as the leaves unfold, feeding begins, 

 generally on the upper side of the leaves in the angle between the mid- 

 rib and the first or second vein. The resulting gall first starts as a de- 

 pression at the point of attack, which gradually deepens and is finally 

 closed from above by the growth of the leaf. The opening is a narrow 

 slit or furrow parallel with the mid-rib or one of the large veins and 

 scarcely noticeable from above. There is a high mortahty among the 

 immature stem-mothers. Out of thirty lice that were observed to 

 start the formation of galls, only four lived to reach maturity. 



Stem-mothers were first observed giving birth to young on the first 

 day of June. The greatest number of young known to be borne by a 

 single stem-mother was 172, while the average was about 75. 



Winged Summer Migrants — Fundatrigenia of European Writers 



All of the progeny of the stem-mothers developed wing pads and by 

 June 20, some had acquired wings and were leaving the galls. By 

 July 20, 90 per cent of the galls were deserted. 



On July 3, a Pemphigus having all the structural characteristics of 

 the winged individuals in the galls was observed on the leaves of Cheno- 

 podium, giving birth to young. The young at birth were enveloped in a 



» Page 24, Twenty-fourth Annual Report of the Colorado Experiment Station. 



