24 Diasi)incB. 



CHAPTER V. 



DlASPIN^. 



' Insects having a separate covering-scale composed partly of 

 the exuviae and partly of secretionary matter. Adult female with- 

 out limbs. Mentum monomerous.' 



The form of the scale — or puparium, as it is often called — 

 varies from circular to oblong, or even linear. Its structure is in 

 all cases practically identical, and can be best understood by 

 following the life-history of a typical Diaspid from the ^'g^ to the 

 adult stage. 



The eggs, in the oviparous species, are deposited beneath the 

 parent scale, and are retained there until hatched. Some few 

 species are ovoviviparous, and in such cases the young make their 

 escape at once from beneath the edges of the scale. 



The small oval larvse are at first very active and of a wandering 

 disposition, with well-developed limbs and antennae. They at once 

 set out in search of a suitable spot upon which to fix themselves 

 for life ; for, having once settled down, they cannot afterwards 

 renew their wanderings, but remain attached to the same spot by 

 their sucking-tubes, which are buried deep in the tissues of the 

 plant. Soon after the insect has become stationary, a very thin 

 layer of waxy secretion is deposited over the dorsal surface, some- 

 times forming a thickened central boss or a raised ring. 



The first larval skin or ' pellicle ' is shed comparatively early 

 in the life of the insect. A curious difference in the mode of 

 effecting the ecdysis is noticeable between Aspidiotus and other 

 genera. In Aspidiotus the larval skin splits along the margins, 

 completely separating the dorsal and ventral halves, which subse- 

 quently become incorporated respectively into the dorsal and 

 ventral scales of the puparium. In this case the visible part of 

 the pellicle will be destitute of the sheaths of the antennae or limbs 

 (//. I. fig. 8). In all other genera that I have observed the whole 

 of the larval skin is attached to the dorsal scale of the puparium, 



