80 
Transactions of the Boyal Society of South Africa. 
the mealy covering and lateral and caudal filaments, which many of them 
possess, obscure the extremities. Further, when dealing with old females 
which have completed oviposition the body is often shrunken and is much 
smaller than the mounted specimens indicate. On the whole I think it is 
most satisfactory to give the approximate size of the largest living 
specimens observed and an average of the size of adults when mounted. 
There is undoubtedly a slight variation in size of individuals of the same 
species caused by difference of food-plant and also by climatic conditions ; 
for this reason the host-plant and date of collection should be given with 
descriptions. 
(b) Shape. — The normal shape of the body is elongate oval, but in a 
few cases there is an important variation, which may be sufficiently pro- 
nounced to at least suggest generic relationship. In Bhizoecus the body is 
exceptionally long and narrow, but this character is also found in a few 
species of Pseicclococcus. In some instances the shape is given as sub- 
globular, while in Antoniiia natalensis sp. n. the body is in the shape of 
half a pear, and in Natalensis g. n. the segments of the body are quite 
characteristic, as shown in the sketch (Fig. 11). 
It may be seen that such variations, w^hen constant, are of importance 
in the determination of species, especially as they are found in only a few 
cases. 
{c) Colour. — The descriptions of colour apply really to three distinct 
phases : (1) the colour of the mealy secretion, (2) that of the body as seen 
through the secretion, and (3) that of the body when freed from secretion, 
as when first dropped into boiling KOH. 
The mealy secretion is most often white, but it may be tinged with 
yellow, as in Ps. filamentosus Ckll. ; bright yellow, as in Ps. aurzlanatus 
Mask. ; or decidedly buff, as in Ps. iceryoides (Mask.) and Ps. nipae 
(Mask.). In most cases the dorsum of the insect is densely coated with a 
white, powdery, mealy secretion ; but, in a few instances where the 
insects are enclosed in a cottony mass (Ps. transvaalensis sp. n.) the insect 
itself is practically free from such meal. The same may be said of the 
young females of Pseudococcus fiagrans sp. n., which are embedded in a 
dense layer of white, powdery wax between the leaf-bases of grass ; but 
later, when the insects ascend the grass-stems apparently to await the 
males, a slight mealy covering is secreted. In such cases the true body- 
colour may be seen, but in many others, where the dorsum is thickly 
covered with secretion, the true colour is only seen on the ventral surface 
where the meal is scant, or when the insect is rubbed, or dropped into hot 
KOH. The most common colour is pinkish, or purplish, but many varia- 
tions have been recorded ; and, just as constant variations in shape may 
be useful in the determination of the species, so the differences in colour 
may give a clue to relationship at least. Thus, while many species show 
