THE INJURIOUS SCALE INSECTS AND MEALY BUGS, &c. 227 
it is almost flat and semi-transparent, revealing the snblying insect and 
eggs, giving it a yellowish tinge and a waxy texture. The old scales 
become more opaque, are pale ochreous or straw-coloured, and have a 
much rougher texture. To the unaided eye the living examples appear 
like minute scales of yellow wax. 
The male scale is very much smaller than the covering scale of the 
female, is pure white, very elongate, narrow, has three strong ridges 
arranged longitudinally, and is accompanied by a varying quantity of 
loose woolly filaments. Minus the latter character it is quite inseparable 
from ^many other species and genera (fig. 99, C, shows a typical male 
Fig. 97.— Boisbuval's Scale 
{Diaspis Boiscliivalii) on portions of Palm leaf (nat. size). 
■scale of this genus). One interesting characteristic of this species is 
that the male scales arrange themselves in small groups or colonies ; a 
very marked habit where the insects are not over- numerous ; but when 
overcrowding takes place the somewhat isolated colonies unite and form 
a mass, often completely covering portions of the food-plant, which is 
clearly illustrated in*] the photograph. (Fig. 97, B.) Where such enor- 
mous colonies exist there is such an excess of woolly filaments as to 
almost obscure the form of the scale. The separation of the sexes is 
sometimes shown to a remarkable degree, although the distance is not 
usually very great. Thus on Palms the male scales are usually con- 
