62 BULLETIN 826, U. S. DEPARTMENT OF AGRICULTURE. 



It seems to the writer that the Mindarinae give a fair idea of the 

 ancestors of the Eriosomatinae and may even represent a group 

 dominant in earlier times from which the Eriosomatinae sprang. 



Only one genus is represented. 



Genus MINDARTTS Koch. 

 Plate IX, A-F. 

 1857. Koch, Die Pflanzenlause Aphiden, p. 277. 



The peculiar genus Mindarus was erected by Koch with ahietinus 

 Koch as type. This species is the only one in the genus, although it 

 has been redescribed as ScJiizoneura pinicola Thos. and ScMzoneura 

 ohliqua Choi. 



Characters. — Cornicles present as mere rings. Large wax plates present. Alate 

 forms with six-segmented antennas armed with oval sensoria. Fore wings with the 

 media once branched; radial sector inserted mesad of the long narrow stigma, thus 

 giving a very long stigmal cell; hind wings with both media and cubitus present. 

 Cauda rather long, not rounded, but somewhat conical or even spatulate. Sexes small 

 and apterous, beaks present and feeding taking place. Oviparous female with the 

 ovaries developed and laying as high as 9 eggs. Forms living free upon the twigs of 

 conifers which become somewhat distorted by the feeding of the insects. 



Type (monotypical\ Mindarus abietinus Koch. 



Subfamily III, ERIOSOMATINAE. 



The subfamily Eriosomatinae is composed of insects which are 

 perhaps as specialized as any of the Aphididae. They show a re- 

 markable development of the habit of gall formation and in this 

 respect parallel the Hormaphidinae. The insects of that subfamily,, 

 however, evidently have developed the habit independently. Many 

 previous authors have placed all of these forms hi the present sub- 

 family. This, the writer believes, is incorrect, as shown by the biol- 

 ogies of the insects. The sexual forms give a true understanding of 

 the relationships and of the genera which should be included in the 

 Eriosomatinae. All of the forms included by the writer show evi- 

 dence of a common origin in that the sexes have become degenerate. 

 They have become small apterous forms and have lost the mouth parts 

 and the ability to take food. That this was not their original condition 

 is clearly shown by the history of the family and also by the fact that 

 the sexual forms of some species Have a beak when born, but lose this 

 at the first molting. Other species even at the time of birth are devoid 

 of all but a rudimentary trophictubercle. The reproductive system 

 of the female has become greatly altered. As previously pohited 

 out by the writer, the early development of the reproductive system 

 of the sexual female corresponds exactly to that in the apterous forms 

 and to that of the oviparous forms of the more primitive groups. 



Young embryos * * * show that the ovaries are at first similar to those of the 

 parthenogenetic form. There may be distinguished the four chambers on each side 

 containing egg cells and nutritive cells. In later embryos most of the egg tubes are in' 



