EDITORIAL. 
INSECTICIDE INVESTIGATIONS. 
A further report on the insecticide investigations being undertaken 
at the Oregon Agricultural Experiment Station presents one or two 
yaluable conclusions. In aw abstract of the work published in” The 
Review of Applied Entomology, it is stated that the investigations show 
that acid lead arsenate is more effective than the basic salt, the pro- 
portion assimilated by the larve being greater. One pound of the 
acid lead arsenate in 400 U.S. gallons of water was effective against 
very small tent caterpillars (Malacosoma), and would probably be 
equally so against newly-hatched codlin moth larvee (Cydia pomonella). 
The ordinary commercial lead arsenates are nearly pure acid lead 
arsenate. The powdered form is superior to the paste and keeps better. 
Substances known as spreaders, which increase the covering power arid 
adhesiveness of the spray, add greatly to its efficiency. The most prac- 
tical in order of merit are: caseinate, glue, soap bark, and oil emulsion. 
They are not improved by the addition of phosphates or sulphates. The 
three factors, method of application, the spray solution, and the spray 
material, all affect the efficiency of the spray, and the improvement of 
any one of them decreases the relative importance of defects in the 
other two. In the calyx application for codlin moth a fine, misty 
spray is as effective as a driving spray. But undue importance should 
not be attached to the calyx spray. In Oregon usually less than half of 
the infestation is due to the calyx entry; it is the last brood of larve 
which infests the fruit late in August and early September that causes 
the heavy losses and is hardest to control, owing to the difficulty in 
timing the spray. The calcium arsenates have a high killing efficiency, 
but are not so staple as the lead salts, and an excess of lime is advis- 
able in solutions of them. There is probably no adequate reason for the 
abandonment of lead in favour of caleium arsenate for orchard work. 
Nicotine sulphate is a powerful repellent for tent caterpillars, and if 
feeding does take place, even weak solutions kill almost instantly. It 
is an effective ovicide for codlin moth, especially with the addition of 
Soap, but is not to be recommended as a substitute for the standard 
‘rsenate sprays in codlin moth control; though it may prove highly 
efiicient as a substitute for the arsenate spray in the July application 
where a serious summer reinfestation of aphides is present or again in 
Combination with the last summer application of arsenate with a 
‘preader, as a further insurance against the damage caused by the last 
brood of larvee. 
797, 
