29 
WHITE SCALE (Leerya purchasi). 
This unwelcome intruder was first observed by Dr. Purehas on 
kangaroo acacia, in the cemetery gully, Auckland, in 1876, and the 
female insect was described by Mr. W. M. Maskell in 1878 as Icerya 
purchasi, It was supposed to have been introduced with wattle from 
Australia; but it is not a native of that continent, and in all proba- 
bility has come to our shores with imported citrads from the Fiji 
Islands or California. Unhappily it is now found infesting citraceous 
plants from the Bay of Islands to Nelson. In some localities it is 
plentiful on wattles; less frequent on furze, manuka, &c.; more 
rarely still it may be found on the apple, plum, and peach ; but I have 
never seen it in quantity on either. It usually occurs in seattered or 
linear masses on the twigs and small branches of the lemon, citron, 
&c., and on the under surface of leaves. Not infrequently it forms 
superficial patches, covering two or three square inches on the trunk. 
The mature female insect is fully one-quarter of an inch in length. 
In the young state it is of a reddish-brown colour, and is furnished 
with a pair of short antenne, a pair of eyes, a short beak adapted for 
piercing the epidermis of plants and extracting their juices, and three 
pairs of short legs. In this state it is oval in shape, and exhibits a 
certain amount of activity; in a few days the reddish-brown colour is 
obscured by aflexuous, cottony outgrowth, and the oval shape is partially 
_lost. Minute tufts of black hairs are arranged along the lower margin 
of the body. The insect becomes attached to the epidermis by its 
suctorial beak and loses the power of locomotion. It now forms its 
nest between the abdomen and the surface of the twig in such a way 
that the abdomen is gradually elevated and the space beneath pro- 
portionally enlarged for the reception of eggs, which are deposited to 
the number of fifty or more, and are hatched in a few days. I have 
not seen the male insect, but have been assured that it is not uncommon 
in the spring, and exhibits considerable activity, the slightest movement 
of a branch being sufficient to start a number of them on the wing. 
Trees attacked by white scale present a most unattractive appear- 
ance; but, unless suffering from foot-rot, borer, or other plagues, do 
not appear to become so much exhausted as might be expected from the 
vast numbers of the insect. No instances of fatal results from its 
ravages have come under my notice. 
PREVENTION AND CURE. 
Young trees should be carefully examined before planting, in order 
to remove any scale that may have attacked them; dipping them in a 
solution of caustic potash and sulphur would be an excellent safeguard. 
After planting, the trees should be frequently inspected, so that the 
first appearance of the pest may be detected, and prompt measures 
taken for its destruction. In this way it may be prevented from 
establishing itself at but little cost. Should the orchard become 
thoroughly infected, the extirpation of the insect would involve a con- 
siderable expenditure of time and labour. All affected branches should 
be promptly destroyed. 
