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



ment of the ovaries found in the more primitive groups, and has 

 retained in both sexual forms the beak and the ability to feed. 

 This at once suggests a different line of development from that 

 taken by the Eriosoniatinae, although in some of its habits the 

 Hormaphidinae agrees with that subfamily. In other lines, however, 

 marked differences are met with here and one of the most striking 

 of these is development of aleyrodiform generations, which remain 

 stationary upon the host. Such a development is never met with in 

 the Eriosomatinae, although the sexual forms are much more 

 specialized. 



Since many of the genera of the Hormaphidinae are gall formers, 

 sensoria very similar to those met with in the Eriosomatinae are 

 met with here also. Indeed the same annular sensoria found in 

 the Eriosomatini are even more pronounced in the Hormaphidinae 

 and the sensoria on the wing bases are prominent and often, 

 numerous. 



The cornicles in the present subfamily are sometimes absent or, 

 as is usually the ease, reduced to mere rings. In some genera, how- 

 ever, they may be elevated slightly on broad shallow cones, somewhat 

 suggestive of those of Anoecia. No prominent cornicles, however, 

 occur. 



In the wing venation there is often a considerable reduction 

 and this shows also the specialized nature of the insects. The 

 venation is comparable to that met with in the Eriosomatinae. In 

 the fore wings the media is either simple or once branched, the radial 

 sector, cubitus, and anal are present, but the cubitus and anal are 

 often fused near their bases. In the hind wings both the media and 

 cubitus are sometimes present, but often only the media remains. 



Great specialization in wax-producing organs occurs. In many 

 of the forms these agree with the ones found in the Pemphigini. 

 In certain aleyrodiform generations and in some sexual forms 

 agglomerate glands or rather groups of small glands are seen. These 

 may be arranged in different ways and often are placed about the 

 margin of the insect so that it possesses a distinct lateral fringe, 

 very like that of an aleyrodid. In fact some of these insects on this 

 account are very often mistaken for aleyrodids. 



The sexual forms are often quite small and possess large wax- 

 producing areas. Others may lack these. All, however, develop 

 to normal adults. 



The habit of gall formation is very marked here. Indeed, some 

 species form galls on two different species of plants, migrating 

 between the two. 



Characters. — Aerial forms living in galls or sometimes free upon the host. The 



' mesothorax in many forms altered so that its divisions are more or less unobservable, 



the entire mesothorax often showing as only one plate. Scalelike or aleyrodiform 



