16 IJS SECTS AFFECTING THE ORANGE. 



wards be removed by the Coccid, but firmly anchor it in place. When 

 pulled by force from the bark these long bristles separate and curl up, 

 and the insect is powerless to reinsert them or to again attach itself to 

 the plant, and must inevitably die of starvation. 



As soon as the young Bark-louse begins to feed upon the juices of the 

 plant excretions of wax commence to exude from its body. There first 

 appear along the sides and at the end of the body long curled threads 

 of white wax. These form a tangled mass, enveloping the insect ; but 

 this first covering is very delicate, and after a time it partially or en- 

 tirely disappears, owing to the action of the weather. It is succeeded 

 by a covering formed in a similar manner, but of denser texture. This 

 second covering is more persistent; it is in fact the beginning of the 

 permanent scale. 



For two or three weeks after the formation of the infantile scale is 

 completed the external appearance of the insect does not change, butv 

 within a new body gradually forms and separates from the larva skin 

 until the latter becomes a loosened envelope, from which finally the 

 new-formed insect entirely withdraws its body, passing through a split 

 in the under side. "The molted skin is not abandoned, however, but 

 remains, partly covering the Coccid above, and ultimately forms the 

 summit or the extremity of the permanent scale. 



With the old larva skin are cast off the now useless members of the 

 larva, and the insect takes the form of a fleshy sack of very simple con 

 struction. The joints of the body are indicated by fleshy folds, and the 

 hair-like mouth-tube projects from the under side near one end of the 

 body. The thin outer edge of the last or anal joint of the body is fur- 

 nished with minute, horny lobes and spines, and its upper and lower 

 surfaces present numerous pores, through which flows a viscid liquid, 

 the material which on hardening forms the protecting scale. On the 

 under side of the last joint can also be plainly seen the vaginal opening, 

 through' which pass the eggs or young. 



Immediately after molting the body of the Coccid expands, so that 

 it can no longer be entirely covered by the cast skin of the larva, and a 

 portion of the broad terminal joint projects beyond its 'edge ; but the 

 exposed parts are soon flooded with a glutinous fluid, issuing from the 

 pores that stud its surface, and this in a few minutes hardens, and 

 forms an extension of the covering. 



During the growth of the insect which follows the molting of the 

 larva skin, the scale covering receives repeated additions of these thin 

 Iamina3, each of which underlies and projects slightly beyond the pre- 

 ceding layer, and the scale constantly increases in size and in solidity ; 

 while at all times the outer edge remains the thinnest, and therefore 

 the most vulnerable point. Thus the process of growth at this stage is 

 seen to be analogous to that of snails or oysters, which form their shells 

 in an exactly similar manner. 



A considerable interval having elapsed after the first molt, the fe- 



