HEMIPTERA. 147 



highly organized form, as is the rule in the development of animals. With the 

 skin are shed the legs and antennae.* The young scale-insect thus becomes a 

 degraded grub-like creature, with no organs of locomotion. The mouth-parts 

 remain, however, in a highly developed state and are well fitted to perform 

 their functions. This apparatus is not the least remarkable thing in the 

 structure of these insects. It is terminated by a thread-like organ, which is 

 frequently much longer than the body of the insect, and is composed of four 

 delicate hair like bristles. By means of this organ the insect is firmly attached 

 to the plant, and draws its nourishment therefrom. From this stage the devel- 

 opment of the sexes differs. 



The second and last moult of the female takes place, in those species which 

 we have studied most carefully, when she is about twice as old as when the 

 first moult occurred. The change in appearance at this moult presents nothing 

 remarkable. The second cast skin is joined to the first, and with it forms a 

 part of the scale which covers the body of the insect. Sometimes, as in the 

 genus Uhleria (Plate VII. Fig. 9), this moulted skin is very large and constitutes 

 the greater part of the scale; but more commonly the exuviae form but a small 

 proportion of the scale, the greater part of it being excreted subsequently to 

 the second moult. Soon after the second moult of the females takes place the 

 adult males emerge, and doubtless the impregnation of the females occurs at 

 once. After this, the body of the female increases in size, becoming distended 

 with eggs. The oviposition takes place gradually, and, in those species that we 

 have studied, begins when the female is about three times as old as when the 

 first moult occurred. The eggs are deposited beneath the scale, the body of the 

 female gradually shrinking and thus making room for them. (See Plate X. 

 Figs. \b and 2c.) Some species, however, are viviparous. 



The male scale-insect during the early part of its larval life is indistinguish- 

 able from the female. The first moult occurs at the same time and is accom- 

 panied by a similar change, the male larva, like the female, losing its legs and 

 antennas. The second moult is also synchronous with the second moult of the 

 female ; but here the similarity in form between the two sexes ceases. Even 

 before this moult takes place there may be observed the formation of rudiment- 

 ary limbs beneath the transparent memberless skin of the larva; and after this 

 skin is shed, the male, now in the pupa state, differs remarkably from the 

 female. The male pupa has long antennae, and its legs and wings, although in 

 a rudimentary state, are very large. The duration of the pupa state in those 

 species which we have bred, in short, lasting but a few days; and then, after a 

 third casting of the skin, the adult male appears. 



The outline figures on Plates IV., VI., and IX. represent the insect in 

 this stage. The anterior wings, though very delicate, are large, and enable 

 the male to fly readily. The posterior wings are represented only by a pair of 

 halteres. These insects resemble in this respect the flies, gnats, and other 

 insects belonging to the order Diptera, or two-winged insects. The posterior 

 end of the body is furnished with a style, which is sometimes nearly as long as 

 the remainder of the body, and is the external organ of reproduction. As our 

 figures represent only a dorsal view, the most remarkable character of the 



* Rudiments of antennse are sometimes retained, as in certain species of Mytilaspis. 



