18 BULLETIN NO. 1, DIVISION OF ENTOMOLOGY. 
strong for long scale, are not sufficiently penetrating to kill the eggs 
of purple scale (iM. citricola). I think that by next spring Dr. Neal will 
have considerably modified his conclusions, and will agree with me in 
recommending a higher grade and more penetrating emulsions. In re- 
gard to the removal of the scales from the tree by a second application 
one week after the first, I cannot but think that he is mistaken. 
In regard to cost of the materials used in Dr. Neal’s washes, his esti- 
mates are somewhat higher than mine, and I think he pays 5 cents per 
box more for milk (condensed), and probably a somewhat higher price 
per pound for whale-oil soap than we do here. 
The following are my estimates for a standard wash of whale-oil soap 
and kerosene, emulsion 66 per cent. oil, diluted 1 to 9 (1 gallon emul- 
sion = 10 gallons wash): 
Whale-oil soap, 4 pound, at 10 cents retail price, 2.5 cents; water, 1 
gallon, nothing; kerosene, 2 gallons at 20 cents, 40 cents; total, 66 per 
cent. emulsion = 3 gallons, 42.5 cents; one gallon costs 14.166 cents. 
Notr.—There is a slight loss by water-shrinkage or otherwise, so that 
when small quantities are made it is sufficiently exact to put the cost 
of the emulsion at 15 cents per gallon. 
One gallon emulsion = 10 gallons wash: cost, 14 cents; without allow- 
ance for loss, 1.416 cents. 
At wholesale rates, 18 cents for kerosene and 8 cents for whale-oil 
soap, the cost of the emulsion would be about 2 cents per gallon less; 
4. €., 122 cents. 
With aquapult pump and cyclone nozzle, 4 gallons of wash is suffi- 
cient for 30 trees of small size, such as are usually furnished at the 
nurseries for transplanting; cost per tree, about two-tenths cents (ex- 
actly .18). 
Trees which have been transplanted and have made two years’ aver- 
age growth in the grove (3 or 4 years from the bud) require one gallon 
of wash per tree: cost about 15 cents (exactly 1.416 cents). 
Bearing trees of full size will require from 5 to 10 gallons of wash: 
cost, 7 to 14 cents per tree (average about 10 cents per tree). 
Very respectfully, 
H. G. HUBBARD. 
Prof. C. V. RILEY, 
Entomologist. 
