224 MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 



tioU; and, Stationing itself on the under surface of the leaf, very soon 

 causes the same to swell and curl by the irritation and punctures of its 

 beak. The curl is usually from the lateral edge, and the more normal 

 form it takes is shown at Fig. 128, c. It is, however, very irregular, and 

 takes on many different forms, according as it is produced by one or 

 several stem-mothers settling on the same leaf, and as it affects a por- 

 tion of one leaf only or embraces several from the same bud. At first, 

 pale yellowish-red with dark members, the stem-mother increases in 

 size more or less rapidly, depending to some extent on the development 

 of the leaf. Moving about in her curled house, within which she is 

 destined to live and die, this stem-mother goes through her last moult, 

 and attains maturity about the twelfth day from the time of hatching. 

 This period may be lengthened by unfavorable weather, as an indefinite 

 period of legarthy, both of plant and insect, may ensue, after hatching, 

 if the temperature be too low. The number of molts I have not definite- 

 ly ascertained, but from analogy there will be three. Having attained 

 maturity, she commences peopling her pseudo-gall with young at the 

 rate of about one every six or seven hours, according to the temperature, 

 increasing in bulk "^nd prolificacy from day to day, until by the early 

 part of May, in the latitude of Saint Louis, she has attained her fullest 

 development, and soon perishes. She may attain to nearly four milli- 

 meters in length, and, with greatly swollen body, be almost as wide 

 (Fig. 128, b). Her immediate issue, or the second generation, are like 

 her in many respects, but never grow to be quite so large. The individ- 

 uals of this generation soon accumulate in great numbers around her, 

 and in their turn commence to bring forth young, some remaining with- 

 in the original curl, others scattering to fotmd new colonies. Their is- 

 sue, or the third generation, show certain marked structviral differences 

 from the first (see description), and. are destined to become winged. 



"During most of the month of May, we may find, where large clus- 

 ters of leaves are affected, the few more or less exhausted stem-mothers, 

 and these second and third generations in every stage of development. 

 As the lice increase in number, the leaves no longer protect them but 

 present on both sides multitudes of busy atoms — livid, old, and paler 

 young — those with wings and those getting wings — interspersed with 

 white exuviae, cottony secretion, and globules of pearly liquid. At the 

 same time, in single curls of more terminal leaves, we may find the 

 second generation of wingless mothers surrounded by smaller colonies, 

 all of which will become winged. The winged females (Fig. 128, d) are 

 short-lived, bringing forth a dozen or more pseudova at average inter- 

 vals of about half an hour. The glossy pellicle that compresses all the 

 members of their newly-born issue is ruptured very shortly after birth, 

 and is worked off in the course of about ten minutes. These facts are 

 easily ascertained by confining the winged mother, but the exact posi- 

 tions to which the pseudova are naturally carried I have not been able 

 to definitely learn; but we may rest pretty confident that they are con- 

 signed both to the leaves and to the twigs. The young lice, forming 

 the fourth generation, are very active, running swiftly in all directions. 

 In color, they are at first of a pale and bright red, but soon acquire a 



