62 BULLETIN 826, U. S. DEPAKTMESTT 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 MINDARUS Koch. 
Plate IX, A-F. 
1857. Koch, Die Pflanzenlause Aphiden, p. 277. 
The peculiar genus Mindarus was erected by Koch with abietinus 
Koch as type. This species is the only one in the genus 7> although it 
has been redescribed as ScMzoneura pinicola Thos. and ScMzoneura 
obliqua Choi. 
Characters. — Cornicles present as mere rings. Large wax plates present. Alate 
forms with six-segmented antennae 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. Chiparous 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 in 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 pom ted 
out by the writer, the early development of the reproductive s} r stem 
of the sexual female corresponds exactly to that hi 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 
