INSECT NOTES FOR I9II. 245 



tied on a partly grown maple leaf (the inner, newest, third pair 

 of the cluster of maple leaves) between two ribs at the base of 

 the leaf with her head at the angle of the ribs. She had given 

 birth to one nymph which stood with three legs on each side 

 of a rib and its beak plunged into the rib. The stem-mother 

 is very much smaller than the apterous forms on the alder. The 

 progeny of the stem-mother becorne winged about the middle 

 of July or a little later at which time the infested leaf looks 

 like the accompanying figure 96. These are the spring migrants 

 and they desert the maple for the alder before bringing forth 

 progeny. 



In order to ascertain whether t he advent of the maple 

 migrants are an annual necessity for the development of the 

 species on the alder, a vigorous colony of hibernating nymphs 

 was enclosed on alder in a screen house in the spring of 1909 

 and protected for two years against migrants from the maple. 

 The colony existed for these two years in a healthy condition 

 and, protected as it was from natural enemies, thrived much bet- 

 ter than the infested alder. It is of interest to note that both 

 falls in the third generation winged migrants left the housed 

 alder, and not being able to reach the maple, died on the inside 

 of the screen in great numbers. 



How long this independent apterous viviparous parthenogen- 

 etic cycle on the alder could be maintained is not known. The 

 experiment in question showed that a large colony was in good 

 condition at the close of the second season, but by Sept. 8 of 

 the second year (1910) one bush had been completely killed by 

 the sapsucking colony and the sticky honey dew and the attend- 

 ant fungus. The fiocculent appearance of an infested alder 

 branch is shown in figure 97. The other stems were so sickly 

 that they gave no promise for food a third season so the obser- 

 vations were closed with the evidence of two years. 



A counter experiment is planned in which an uninfested 

 alder will be caged and only the migrants from the maple ad- 

 mitted in order to ascertain whether their progeny will estab- ' 

 lish a continuous viviparous cycle upon the alder or perhaps it 

 would be better stated, in order to ascertain what will happen. 



The economic aspect of this species varies with the locality. 

 In Maine the alder (Alntis incana) along the rivers and streams 

 is not valued and the insects infesting this growth are not sig- 



