country much before 1850. Its spread since has, however, been rapid, 

 and it now occurs practically wherever the apple is grown. It has 

 been reported to this Bureau from no less than thirty-tive States and 

 Territories and nearly one hundred localities. It is particularly abun- 

 dant and injurious in the latitude of the Ohio Valley. While seem- 

 ingly, therefore, somewhat affected by severe cold, it is able to thrive 

 in the climate of the northern tier of States on the one hand and in 

 that of Louisiana, New Mexico, and 

 southern California on the other. 



NATURAL HISTORY AND HABITS. 



In common with most aphides, 

 this species has a complicated life 

 history, some of the details of which 

 are still lacking. Thecommonforms, 

 both on the roots and above ground, 

 are wingless aphides, not exceeding 

 one-tenth of an inch in length, and 

 of a reddish-brown color, and abun- 

 dantly covered, especially in the 

 aerial form, with a flocculent waxy 

 excretion. These are so-called 

 agamic females and reproduce them- 

 selves by giving birth, as observed 

 by many entomologists, to living 

 young indefinitely, perhaps for years, 

 without the intervention of other 

 forms. The newly born larvfe have 

 none of the white excretion, which, 

 however, soon appears as a minute 

 down when they begin to feed. 

 These aphides are also peculiar in 

 lacking the honey tubes common to 

 most aphides, but exude the honey- 

 dew from the tip of the body. In October or November, or earlier in 

 the South, among the wingless ones numbers of winged individuals 

 appear, which are also all females, and are the parents, as shown by 

 the observations, partly unpublished, of Messrs. Howard and Pergande, 

 of a true sexed generation of minute, wingless, larviform aphides, the 

 females of which, as in the case of the grape root-aphis, give birth to a 

 single "winter egg." This egg is attached within a crevice of the 

 bark, and, probably, following the analogy of the phylloxera, hatches 

 in the spring into a female aphis which originates a new aerial colony. 

 The winged females appear somewhat abundantly in autumn, and are 

 one of the means of the dispersal of the insect. They are very minute. 



Fig. 2.— Woolly aphis {S liizoneura lanigera): 

 a. Root of young tree illutratirig deforma- 

 tion; b, section of root with aphides clus- 

 tered over it; c, root aphis, female, a and h. 

 Natural size; c, much enlarged. (Original.) 



