20 
Elementary Manual of Zoology. 
situated on the back, The insect feeds on Dhak (Butea frondosa), 
Ber (Zzyphus jujuba), Pipal (Micus religiosa), Kusum (Schleichera 
trijuga), Babul (Acacia arabica), and numerous other forest trees, 
It yields two crops in the year and forms a valuable article of forest 
produce, for India supplies the world with lac. The cochineal insect 
(Coceus cacti) secretes a valuable dye. An inferior variety flourishes on 
prickly pear (Opuntia) in India and is used to a small extent in native 
dyeing, but success bas not hitherto attended the attempts that have 
been made to introduce into India the Mexican variety, which 
produces the best dye. 
Amongst the Coccidw the females are wingless creatures, which 
attach themselves to plants and gradually lose their power of locomo- 
tion, so that they often appear like little scales, The males are usually 
active creatures with but one pairof wings. The larve crawl out 
from beneath the mother insects, where the eggs are laid, and are 
liable to be carried considerable distances by the wind, thus spreading 
the species from tree to tree. They injure the plant by sucking up 
its sap by means of the delicate proboscis with which they are armed. 
Remedies against scale insects,—In America kerosine and soap emul- 
sion applied in a very fine spray with a force pump has been found 
an efficient remedy. In the case of the scale insects which attack 
coffee and tea in India also, experiment has shown that this 
treatment is successful, though its cost has hitherto prevented its 
adoption generally. It will probably be found applicable in the case 
of nurseries and valuable fruit trees that happen to be attacked, butis 
out of the question in forests.) Washes made of solutions of resin 
soaps have also been recommended, Another system known as the 
‘‘ gas” treatment has been adopted upon a considerable scale for rid- 
ding orange trees in California of scale insects. It consists in genera- 
ting hydrocyanic gas under a kind of movable canvas tent which is 
thrown over the bush, This method is said to be extremely effective, 
but is only likely to be applicable under very exceptional circum- 
stances. The fact that scale insects are largely distributed by the 
action of the wind, which blows the young larve from one tree to 
another, makes wind breaks consisting of high trees often of value 
for the protection of crops which might otherwise be attacked. For 
trees, however, to be of any. use for the purpose, it is of 
course essential that they should not be subject to attack from the 
* Kerosine and soap emulsion is best made by churning with a force pump two 
parts of kerosine oil with one part of hot soap solution; the soap solution to be made by 
boiling about half o pound of soap to each gullon of water. The strength of the applica- 
tion must vary according to the nature of the insect to be dealt with and that of “the 
plant attacked, but when applied in the proportion of twelve parts of water to one of the 
emulsion, in a very fine spray through an eddy nozzle by means of a force pump, it will 
kill most scale insects without appreciably injuring the plant, 
