The Delta independent., 1909-03-05
PRACTICAL
ENTOMOLGY
An Up-to-ddte Problem in Eco
nomic Entomology.

nomic entomologist are varied and
furnish an unlimited field for investi-
cation and experiment. The life
history of most of our common de-
structive insect pests has been care
fully determined, and some of the
greatest problems now confront the
men whose duty it is to devise new
and improve old methods for control
In the case of the codling moth we
have an exemplification of the fore
going fact.
There is probably no insect of great
economic Importance that is more re-
sponsive to treatment than this insect.
In the orchard sections of Colorado
the apple growers have been able to
harvest their crop from ninety to
nincty-nine per cent. free of worms.
This exceedingly high percentage of
good fruit is only attained where ar
senical poisons are applied in great
enough strength, at the right time,
and with degree of thoroughness
necessary to successful work. Some
times it is possible to use too much of
a good thing, and in their eagerness to
get the highest possible percentage of
worm-free fruit the orchardists of
western Colorado have been brought
face to face with that very fact.
By very careful work, extending over
a period of several seasons, DIR. w. p.
Headden, of the Colorado Agricultural
College, has determined that many
trees in our western slope orchards al e
dying from arsenical poisoning and
that there is grave danger, unless the
present methods of controlling the
codling moth are modified or super
ceded by something better.
A careful study of spraying methods
in the orchards the past season re-
vealed three important facts: In prac-
tically every case the amount of arsen-
ate of lead used was in excess of the
amount required for successful control.
Nearly all of the growers are spraying
too many times. The trunks and
larger limbs of trees are drenched until
spray runs in stream to the ground.
Taking up these points in their order:
1t is absolutely necessary to use enough
of the arsenate of lead so that the little
larvae will be poisoned as they enter
the apples. How much is required and
how much are people using? 1t has
been demonstrated thoroughly in Colo
RADIO that a pounds of arsenate of lead
to 100 gallons of water is just as effec-
tive as a greater amount. Prof. A. L.
Melander, of the Washington Agricul-
tural College, has been carrying on ex-
tensive experiments in old, neglected
orchards where codling moth was
known to occur in abundance, and has
had perfect success with 2 pounds per
100 gallons of water, and is recon-
mending that strength. We are in
hopes that further experiments in Col
orado will justify US in recommending
like amount, but for the present we
would urge that no more than 4 pounds
be used. In nearly every orchard vis-
tied last season from to 10 pounds of
arsenate of lead per 100 gallons of
water were used, waste of at least
two pounds per 100 gallons of water.
Figured in dollars and cents-if the ar
senate of lead costs $3.50 per 100
pounds there would be waste of 25
cents to every 100 gallons of water:
counting 8 gallons of the spray mixture
to tree, and 100 trees to the acre.
there would be loss of 81 25 per acre
all because of an excessive amount of
arsenate of lead being used.
Two sprayings if thoroughly done,
and at the right time, will control the
codling moth so that any further ma.
terial or labor necessary for extra
sprayings will be wasted. The first
spraying is more important. 1t should
be done when the petals fall from the