432 ENTOMOLOGICAL NEWS. [Dec. , '07 



seem that the dimorph, from its diminutive size, is unharmed, 

 as parasites and predacious insects rarely trouble it, and for 

 weeks it remains on the leaf where it first settled. It taps the 

 vascular system of the plant where its food is most abundant. 

 Abundance of food, however, does not tend to enlarge this 

 form, for it is never larger than when a few minutes old. 



Last fall the apterous sexual forms were kept under ob- 

 servation, and by marking trees where the oviparous females 

 had deposited eggs, I felt quite sure that the following spring 

 I should be able to take the stem mothers when the eggs 

 hatched. I took branches containing eggs into the laboratory 

 of the Agricultural College as soon as the buds began to swell, 

 but those did not hatch, and Professor Gilette was fortunate 

 enough to find young on the trees on February 23d. Some 

 of these may have been hatched for a week or more. On 

 March 10th, these stem mothers began reproducing. One of 

 these was separated on the 13th, and on the 25th had given 

 birth to one hundred and seventeen young. I accidentally killed 

 her at this time, so cannot say how many she might have pro- 

 duced. Another died after producing one hundred and fifty- 

 four. All of the first two generations are apterous. The third 

 generation produces both alate and' apterous forms. The 

 dimorph does not appear until the fourth generation. 



Why this form should appear in the fourth generation, or 

 in any other, is a mystery. I know of no other animal that 

 gives birth to young that are apparently useless to the species. 

 It would seem to be a case of the survival of the unfit, as it 

 neither reproduces nor aids the species in any way. 



The cuts have been made from drawings by the station 

 artist, Miss M. A. Palmer. Fig. I represents an apterous fe- 

 male of second generation ; Fig. II, an alate female of the third 

 generation; Fig. Ill, a dimorph which is of the fourth gener- 

 ation. 



(Explanation of Plate XVII.) 



Chaltophorus ncgundinis: — I, Apterous female belonging to second gen- 

 eration, X 25 diameters ; II, Alate female belonging to third generation, 

 X 25 diameters; III, Dimorph belonging to fourth generation, X 61 

 diameters. (Miriam A. Palmer, artist,) 



