14 



Similarly, at the next moult, the adult female (3 (/) is sufficiently 

 protected, for a time, by the exuviae of the previous two stages. 

 Accompanying the subsequent growth of the insect the covering is 

 completed by a further extension of the secretionary appendix. The 

 eggs are deposited beneath this composite scale. The adult male (fig. 

 1) is provided with four large ocelli, two on the upper and two on the 

 undersurface of the head. Its abdomen ends in a long, slender point, 

 the penial sheath. There are no caudal filaments. The four genera 

 of Diaspi)iae., represented in this country, are Aspidiottis, Lepido- 

 saphes { = j\[i/tilasiiis), Diaspis, and Chionasjns. They may be dis- 

 tinguished by the following characters of the covering scales : — ■ 



Aspidiotun. — Scale of female (fig. 4 a) more or less circular; the 

 larval and nymphal exuviae supernnposed and completely surrounded 

 by the secretionary appendix. Scale of male similarly constructed, 

 but including the larval exuviae only (fig. 4 b). 



Lepidiisapliefi. — Scale of female (fig. 4 /') elongate, mussel-shaped ; 

 the larval and nymphal exuviae overlapping, situated at or beyond 

 the anterior extremity of the secretionary appendix. Male scale 

 similarly constructed (fig. 4 e). 



Dias]>is. — Scale of female (fig. 4 c) more or less circular ; the 

 exuviae usually overlapping, surrounded by the secretionary appendix. 

 Male scale (fig. 4 d) of a different character; elongate and more 

 or less distinctly tricarinate, the larval exuviae situated at the 

 anterior extremity. 



Chioiiaspu. — Scale of female (fig. 4 /;) elongate or pyriform ; the 

 exuviae overlapping, situated at or beyond the anterior extremity 

 of the secretionary appendix. Male scale (fig. 4 //) elongate, 

 tricarinate. 



We have five species of Aspidiotus occurring in the open : — 



A. ostreaefoniiin, Curtis. The so-called " oyster-shell scale," on the 

 stems and branches uf birch, horse-chestnut, poplar, apple, 

 plum, and various fruit trees. Scale very inconspicuous, 

 blackish or dull brown, assimilated in colour to the bark upon 

 which it rests, often with the superficial fibres of the bark 

 incorporated into the surface of the scale. 



A. havariciis, Lindinger. On Collinia vuhjaris and Erica cinerea. 

 Scale brown, of the exact tint of the bark of the heather. 



A. zonatiis, Frauenfeldt. On oak. Scale dull greyish ochreous, on 

 the terminal branches of the tree. Male scales pale, trans- 

 lucent ochreous ; on the undersurface of the leaves. 



A. hritannicii>i, Newstead. On holly and box. Male and female 

 scales brown or brownish ochreous: on the twigs and foliage. 



A. hederac (Vallot). On Aiiciiba. Scale conspicuous, white, the 

 exuviae pale yellow ; on both surfaces of the foliage. This 

 is an alien that has, within recent years, adapted itself to our 



