6 
is the hind extremity of the insect which presents the characteristic 
features. I do not know whether it is the same with other people, but 
the writer can always judge best of the form of the parts when the 
tail is pointing upward, as in the accompanying figures. This is 
explained by the fact that the eye is more accustomed to judge of 
convexities (e. g., mountain ranges, tree tops, &c.) than concavities. 
Having prepared the specimen, an examination shows various caudal 
structures, known as lobes, plates, and spines. The lobes are more or 
less rounded projections from the margin, of which there is a well- 
developed pair (the median 
lobes) at the caudal extremity, 
and varying numbers of outer 
ones, according to the species. 
The plates, so called, are gland 
hairs, and form a delicate fringe 
adjacent to the lobes; they are 
often branched. The spines are 
A. pemicioour fren lan Cue fine bristles, placed at intervals 
(en plum) (6 chow fhe glandular s gene cae 
hairs er “platy 's. on the margin, projecting more 
nearly at right angles than the 
plates. 
Seattered over the surface of 
Oy the hind part of the insect will 
ty 
be found oval glands, the position 
\ \ { Vf 5 and number of which is often of 
2) QS importance. In connection with 
\ SS the glands at the bases of the 
oS } lobes are found chitinous pro- 
ora cesses, which remain dark after 
= S boiling the insect in caustie pot- 
S PAs ash, and are represented as dark 
o fusiform objects in the figures. 
° The oval glands just men- 
= oe tioned are on the dorsal surface ; 
\ but by changing the focus there 
A. eas fr Cai SG. will come into view, when pres- 
Fia. 2.—Aspidiotus perniciosus and A. howardi: ent four or five SOURS of cir- 
PHaracrere or female (eriotael): cular glands on the ventral sur- 
face, arranged about the genital 
opening. When well developed, these ventral grouped glands consist 
of an anterior or median group and two groups on each side, known 
as caudolateral and cephalolateral. Their function has long been 
doubtful, but Mr. EK. KE. Green (Ent. Mo. Mag., April, 1896, pp. 85-86) 
has hit upon what is almost certainly their true purpose, namely, to 
secrete the waxy powder which dusts the surface of the eggs. In 
accordance with this view, we find them to be very numerous in those 
forms which produce numerous eggs; less numerous in those which 
produce a few eggs at a time, which rapidly hatch; and wanting in 
