EDITORIAL. 
eight powders used as dusts, only D. elliptica and D. uliginosa and an 
unidentified species were found efficient. Used as a powder, Derris 
was found to be equally effective against Clenocephalus canis, Curt. (dog 
flea), Mallophaga on poultry, and Musca domestica, L. Dermanyssus 
gallinew, Redi (chicken mite) was killed in twenty-four hours when con- 
fined to jars, but under natural conditions all the mites were not killed. 
It is of very little value against Cimex lectularius, L. (bed-bugs), Phyllo- 
dromia (Blattella germanica), L., Pseudococcus citri, Risso (mealy bug), 
Orthezia insignis, Doug., Tetranychus telarius, L. (bimaculatus, Harv.) 
(ved spider), and the crawling young of the oyster-shell scale, Lepido- 
saphes ulmi, L., but was effective against Aphis rumicis, L. (bean aphis) 
and Aphis pomi, De G. (green apple aphis). Used as a spray, it proved 
effective against Aphis pomi under natural conditions. The sprays were 
applied with and without soap at strength varying from 1 lb. of powder 
in 25 gallons of water to 1 lb. of powder in 200 gallons of water. Even 
the weakest solution resulted in the death of 98-100 per cent. of the 
aphides. The soap does not increase the effectiveness. Under greenhouse 
conditions it proved effective against A. rumicis at the rate of 1 lb. of 
powder to 400 gallons of water, with the addition of soap at the rate of 
1 lb. to 100 gallons of water. Used as a stomach poison against Lepti- 
notarsa decemlineata, Say (potato beetle), at strengths ranging from 
1 lb. of powder to 16 gallons of water up to 1 lb. to 128 gallons, it killed 
all larvee within forty-eight hours. Other insects against which it 
proved effective include JJalacosoma americana, F. (tent caterpillar), 
Hyphantria cunea, Dru. (fall webworm), Anisota senatoria, S. and A. 
(oak worm), Datana ministra, Dru., and -Phytometra (Autographa) 
brassicw, Riley (cabbage looper). Some insects are more easily affected 
than others, but apparently death eventually occurs in all cases through 
motor paralysis. The toxic principle is probably a resin. 
EFFECT OF SHEEP DIPS ON WOOL. 
The effect of sheep dips on wool was the subject of an interesting 
lecture before the Leeds University Textile Association by Dr. Sydney 
Williamson, of the Cooper Research Institute. The whole discussion 
as to the effects of dips on wool, said Dr. Williamson, had unfortunately 
ceutred mostly in the lime and sulphur dip, the one which the farmer 
himself made for the sake of cheapness. That dip was opposed by the 
manufacturers of the proprietary dips. ‘In spite of much research for 
authentic evidence as to the injurious effects of dip upon wool, he had 
come across nothing which could be regarded as conclusive. He 
expressed the opinion that nicotine in dip was not injurious sé long as 
pure nicotine was used. Carbolic acids, as a rule, were only injurious 
if they contained an excess of alkali, which tended to disintegrate the 
fibres. If a farmer used impure tar oil in dipping, he might get woo! 
which, after scouring, would turn almost brick-red in colour, but such 
instances were rare. With regard to the lime and sulphur dip, he had 
seen a great deal of wool which had been injured. It had become harsh, 
and had lost its lustre, a condition which was probably due to the deposi- 
tion of lime, which formed salts in contact with the fats in the wool: 
These lime salts were probably deposited in the fibre, but he had never 
been able to prove it. Speaking in regard to arsenical dips, Dr. 
Williamson said they were not injurious unless an excess of alkali had 
77 
