Jfo. 1.] RILEY AND MONELL ON APHTDID^. 5 



mences peopling her pseudo-gall with young at the rate of about one 

 every six or seven hours, according to temperature, increasing in bulk and 

 prolificacy from day to day, until by the early i^art of May, in the latitude 

 of Saint Louis, she has attained her fullest development, and soon per- 

 ishes. She may attain to nearly four millimetres in length, and, with 

 greatly swollen body, be almost as wide (Fig. 1, h). Her immediate issue, 

 or the second generation, are like her in many respects, but never grow to 

 be quite so large. The individuals of this generation soon accumulate 

 in great numbers around her, and in their turn commence to bring forth 

 young, some remaining within the original curl, others scattering to 

 found new colonies. Their issue, or the third generation, show certain 

 marked structural difterences from the first (see descriiDtion), and are 

 destined to become winged. 



During most of the month of May, we may find, where large clusters of 

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

 these second and third generations in every stage of develojiment. As 

 the lice increase in numbers, the leaves no longer protect them, but pre- 

 sent on both sides multitudes of busy atoms — li\'id, old and paler young — 

 those with wings and those getting wings — interspersed with white 

 exuvife, cottony secretion, and globules of pearly liquid. At the same 

 time, in single curls of more terminal leaves, we may find the second gen- 

 eration of Avingless mothers surrounded by smaller colonies, all of which 

 will become winged. The winged females (Fig. 1, d) are short-lived, 

 bringing forth a dozen or more pseudova at average intervals 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 ascer- 

 tained by confining the winged mother, but the exact positions to which 

 the pseudova are naturally carried I have not been able to definitely 

 learn; but we may rest pretty confident that they are consigned both to 

 the leaves and to the tmgs. The young lice, forming the fourth genera- 

 tion, are very active, running swiftly in all directions. In color, they are 

 at first of a pale and bright red, but soon acquire a brownish tint. In 

 general ai)pearance, they resemble the young from the stem-mother. 

 The beak is very long, thickened at the end, which always projects 

 beyond the tip of the abdomen, and terminates in a sickle-like point. 

 Experiments made by attaching and confining these young to the trmilc 

 of the tree show that they do not flourish thereon, but naturally crawl 

 out to the more tender, terminal leaves, which they immediately begin 

 to curl. They may be found scattered over an infested tree, with theii- 

 beaks for the most part inserted in the tender leaf-stem or in the mid- 

 rib on the under side, the leaf in such case already beginning to sho^^" 

 the effect of the poisonous puncture. The}' are, however, able to sustain 

 themselves on the tender bark of the twigs alone, and may be ibnntl 

 nearlj' full-grown, there exposed to vicAV and enveloped in the white cot- 

 tony matter, which brushes off' at the shghtest touch. AVhcn full-grown. 



