74 
Transactions of the Boyal Society of South Africa. 
dorsal filaments ; the nature of the integument at maturity ; the presence 
or absence of a covering scale ; the size, colour, shape, and nature of 
covering scale if present the position and nature of the exuviae ; the 
colour of the living insect without the scale. 
After the above observations are complete, and notes have been 
made, specimens should be cleared and mounted for more detailed 
study. 
The microscopic characters of the Coccidae which are utilized for the 
determination of species are found in the exoskeleton. In order to render 
this transparent it is necessary to get rid of the soft body contents, but 
at the same time to retain the chitinous skin of the insect, with its 
appendages, hairs, and spines iti as perfect a condition as possible. The 
easiest method is to treat the specimens with a strong solution of caustic 
potash (KOH) or caustic soda (NaOH) which dissolves all the soft parts, 
but does not dissolve chitin. If used hot, or boiling, this solution acts more 
quickly than when cold. Small specimens, such as the armoured scales, 
are geaerally sufficiently transparent after boiling from 5 to 10 mmutes 
in a 20 per cent, solution of KOH. Larger insects, such as mealy-bugs or 
cochineal insects, may require 20 to 30 minutes. The following particulars 
may be useful. In dealing with armoured scale insects do not scrape a 
stem thickly covered with insects into the KOH solution. Eaise each 
scale separately and pick out the msect on a needle-point which has been 
previously moistened, and place in the KOH, taking care to keep insects 
from similar scales together, as there may be several species on the same 
twig. When possible boil 12 to 20 insects of the same kind, and count 
them as they are transferred to the different solutions. This is especially 
necessary when staining, as the insects are difficult to see when stained 
the same colour as the fluid they are in. For small specimens a shallow 
watch-glass is a useful staining dish, using a little stain. When about to 
transfer the specimens the glass is held above a mirror, placed as a 
reflector, when the insects are easily seen. 
Larger insects, such as mealy-bugs, should be punctured with a needle 
before boiling. This permits of more rapid clearing. Very large, convex 
insects, such as Asj^idojjroctus spp., and some of the Lecaniinae, are too 
large and thick to make a single mount. These are best treated by 
separating the lower surface from the upper by cutting around the margin 
with a fine scalpel or pair of scissors before boiling. The two surfaces are 
then treated and mounted separately. The colour which the body assumes 
in boiling KOH, and whether the liquid is stained or not, should be 
noted. 
If distilled water cannot be easily obtained, rain water which has been 
boiled, and preferably filtered, should be used for making up all solutions 
and stains, and for washing the insects between the different solutions. 
