352 NEW YORK STATE MUSEUM 



Where the pores are fewer the two lines first mentioned can usually be 

 distinguished, but are less crowded than in the extreme form, while the 

 third row is represented by two or three scattering pores or not at all, 

 and the pores at the first incision are two or three in a group close to the 

 ends of the chitinous processes. 



The second stage of A. a n c y 1 u s seems not always definitively differ- 

 ent from the same stage ofA. ostreaeformis, I have seen in mounts 

 from undoubted A. a n c y 1 u s material one or two second stage speci- 

 mens, which had the small, narrow yet distinct second lobes together 

 with absence of the plates that characterize A. ostreaeformis. 

 Similarly, I have seen in A. ostreaeformis mounts second stage 

 specimens that suggest A. a n c y 1 u s. Of course, it is always possible 

 that the two species are breeding side by side and may be taken at the 

 same time in the younger forms, even if they have not been so taken in 

 the adult stage. It seems to me that, in distinction between the two 

 species, if fringing plates are present, whether or not rudimentary lobes 

 appear, it is pretty surely not A. ostreaeformis but is presumably 

 A. ancylus. If plates are not discernible, and a seco nd pair of lobes 

 appears, it is pretty safely the former species. But, where there are 

 neither plates nor second lobes to be discovered, additional evidence 

 should be sought. In any case an identification from second stage 

 material may safely be modified with '' probably." 



Aspidiotus ostreaeformis Curtis 



PLATE 14 AND PLATE 1 5, FIGURE 2 



A. ostreaeformis is one of the large species, the adult female 

 often attaining a diameter of \\ mm according to Dr Marlatt. He 

 gives an extended description and a beautiful figure on page 8i of the 

 Proceedings of the nth afinual ?neeting of the association of economic ento- 

 mologists (U. S. dep't agric. div. ent. Bui. 20, n. s.). 



The median lobes of this species vary somewhat in shape, but are in gen- 

 eral broad with a distinct though shallow notch on the outer margin. The 

 second pair are much smaller but usually easy to distinguish and quite 

 characteristic in shape. They are at least often considerably narrower in 

 proportion than in the specimen represented in my figure. Both pairs are 

 usually heavily chitinized, and sometimes a rudimentary third pair seems 

 to be indicated by the arrangement of chitin beyond the second incision. 



The spines are as in alHed species ; the plates are inconspicuous, but 

 two short stout ones are usually to be discerned at each incision. 



