181.6. J 85 



ON THE GROUPED ABDOMINAL GLANDS OF THE DIASPINM. 

 BT E. ERNEST GREEN, F.E.S. 



Some years ago (in an interesting paper in the Ent Mo. Mag., 

 January, 1889, p. 190), Mr. A. C. F. Morgan drew attention to the 

 function of the grouped glands on the terminal segment of the 

 Diaspince. Remarking upon the general adoption of the term "grouped 

 spinnerets " for these glands, he rightly points out that as they are 

 ventrally situated and are altogether absent in many species, they 

 cannot be very materially concerned with the secretion of the scale. 

 He suggests that these organs may be " ventral salivary glands," and 

 considers them to be in connection with the alimentary canal. 



Mr. Morgan also expresses an opinion that they do not " really 

 open on to the external ventral superficies." I think this is a mistake. 

 That they are in communication with the surface is evidenced by the 

 fact that their presence is almost always indicated on the living insect 

 by an efflorescence of white powdery wax on those parts. 



Mr. Morgan mentions, in corroboration of his theory, that similar 

 glands are frequently present near the base of the oral setae ; and 

 suggests that these represent the submaxillary salivary glands. Upon 

 examination it will, I think, be found that such glands, when present 

 on the thoracic region, are always grouped round the stigmatic 

 openings, and have not in reality any direct connection with the mouth 

 parts, which in this family are usually situated between the anterior 

 pair of stigmata. Here also the glands are productive of a powdery 

 secretion, the purpose of which I imagine to be the formation of a 

 protective covering to the spiracles, freely admitting air while pre- 

 venting the passage of water. Similar glandular pores occur on the 

 stigmatic regions in the Lecaniince, accounting for the lines of white 

 waxy matter that extend across the under-surface of the body from 

 the stigmatic clefts. 



To return to the abdominal glands : it seems to me that they are 

 more intimately associated with the genital duct than with the ali- 

 mentary canal. When present they will always be found grouped 

 around the genital aperture, which opens ventrally, while the anal 

 aperture is upon the dorsal surface of the pygidium. Very similar 

 glands appear in immediate proximity to the genital orifice in many 

 species belonging to other subfamilies and sections. They are very 

 frequently present in Lecanium and allied genera, and I find them 

 , massed round the genital opening in Walkeriana. 



Relying upon these facts I venture to suggest that the glands in 



