Diaspinc^. 3 1 



the Entomologists Monthly Magazine (April, 1896, p. 85), I have 

 drawn attention to the possible correlation between the circum- 

 genital glands and the habit of oviposition. The following para- 

 graph relating to the subject is quoted from that article : — 



' It is a significant fact that, as far as I have at present observed 

 (dealing with Ceylonese forms only), those species of Diaspincs that 

 have no grouped glatids are ovoviviparous, whilst those in which the 

 wax-glands occur are strictly oviparous. Of fourteen species of 

 Aspidiotus, I find that nine are possessed of grouped wax-glands 

 and lay eggs, while five species are glandless and produce living 

 young. I have four species oi Aonidia — all without the glands — 

 and in all the embryo is fully developed before extrusion. The 

 species of Mytilaspis occurring in Ceylon are amply provided with 

 grouped glands, and deposit large numbers of eggs. In Diaspis 

 the same conditions occur. In Fiorinia three oviparous species 

 are provided with glands, and one ovoviviparous insect is without 

 them. The same rule holds good in Chionaspis, with the doubtful 

 exception of Ch. biclavis, Comst.' 



Small groups of similar glands often occur round the openings 

 of one or both pairs of stigmata. Here also the glands are pro- 

 ductive of a powdery secretion, the purpose of which I imagine to 

 be the formation of a protective covering to the spiracles, im- 

 pervious to water while freely admitting the necessary air. 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. The 

 circumgenital glands may perhaps have a somewhat similar 

 function, namely, the secretion of a waxy powder to protect the 

 eggs. 



The anal aperture is always found on the dorsal surface of the 

 pygidium, but its position there varies greatly in different genera, 

 and to a less degree in different species. As a general rule, we 

 find that in Aspidiotus the aperture is nearer the extremity than 

 in other genera, and always below the level of the genital orifice. 

 At the opposite extreme comes Mytilaspis, in which the anus is 

 usually near the base of the pygidium, considerably above the level 

 of the genital orifice. In Diaspis the anal is below the genital 

 aperture, but nearer to it than is usually the case with Aspidiotus. 

 In Chionaspis and Fiorinia the anal is usually slightly above the 

 level of the genital orifice. In Ao7iidia, in which the genital orifice 

 is near the base of the pygidium, the anal aperture is placed about 



