THK MAOAZINI-O 
OF 
Tf)G n^OOL OF AGRIOULTURG, 
COLOMBO. 
AMed as Sajiplnncnt immihl,/ to /A- " Th'Ol'ICAL AGlilCUL'fUHlST:’ 
The following pages include the contents of the Magazine of the School of 
AgncuUurc for Aj)ril : — 
INSECTS AND INSECTICIDES. 
II K Agriciiltiirnl Conferences lately 
held in (picenslnnd have been 
the luenns of bringing together 
many Agriculturists and men of 
Science, whose utterances, spoken 
with authority, have been embodied in a ri*- 
Jiort iSBued by the IJrisbane Department of 
Agricnlture. At one of these Conferences Prof. 
Shelton delivered himself on the subject of 
insect pest.s, and a good deal of the learned 
Professor's advice on this head is worthy of 
consideration. All insects might be said roughly 
to get their food by only two metliods - 
either they are provided with heaks or sucking 
apparatus which they thru.st into the Imrk 
of a tree and draw the juices to themselves, 
or they have powerful jaws and teeth, and 
gnaw into the substance of the tree, or the 
leaf as the case may be. It is important to 
remember that this difference most materially 
affects man's method of treitment and hainl- 
ling. The scale insect, which adheres to 
the leaf and sucks the juices j)lainly cannot 
be got nt with poison in the same way ns 
the other which gets into the substance of 
the leaf and consumes it. In a general way 
the insects which gnaw could easily be reached 
l*y some poison thrown on the leaf itself, so 
that when it consumes the leaf it also takes 
the poison and is killed. In the case of the 
sucking insects, something must be forcibly 
thrown on them, which in itself is fatal by 
contact, and the great agent used for this pur- 
pose in some form or other, is kerosine— in 
f«ct kerosine is the best agent for this class 
insects, and London purple or Paris green for 
the gnawing insects. There are of course many 
other ways of accomplishing the work of destroy- 
ing insects, but none so .satisfactorily as those 
mentioned. I’aris green is an arsenical poison, 
a waste product occurring in the manufacture 
of aniline dyes, and poisonons in the same sense 
as arsenic. .Arsenic might be used in place of 
it, but for various reasons it is not safe. Paris 
green, owing to its colour is not likely to cause 
accidents as arsenic through being left about. 
London purple, another arsenical insecticide, is 
made in a like manner to Paris green, hut it 
differs slightly in composition, and is cheaper 
and stronger and goes a little further in fact. 
Prof. Shelton considers it generally better than 
Paris green. These insecticides, which could be 
ordered through any chemist, might be used in 
two different ways. The common way is to 
lake 1 lb. of Paris green and dilute it with loO to 
‘200 gallons of water. The green will not dis- 
solve, or very slightly, and the mixture could 
be di.stributed with a can, only care should be 
taken to stir it frequently so that the powder 
may not settle nt the bottom of the can. Again, 
the mixture might bo scattered all over a 
tree by means of a force pump. Another way 
of using the insecticides is to take Paris green 
or London purjile ami mix it with 12 parts of 
tine dust, flour, ashes, plaster of Paris, or lime, 
put it in a piece of suitable cloth (so as to 
allow the powder to pass through readily), tie 
it up, attach it to the end of a stick, and 
ivalk along between the rows, shaking the dust 
on the jdants. This is sure, says l*rof. Shelton, 
to kill evei^' insect that exists there. This should 
be done, if po.ssible, in the early morning, 
w'hen the dew- is on the plants. Some prefer 
to use a syringe and a can to be fastened 
to the back, and distribute the poison diluted 
with wntar. In the case of potatoes. Prof. Shelton 
did not think that either Paris green or lamdon 
purple wn,s injurious to the plants themselves 
and states that they could Ihi applied with the ab- 
solute assurance that the potato would not take 
enough of it to influence the plant itself 
