56 BULLETIN 918. U. S. DEPARTZtfEXT OF AGBJCrXTrRE. 
for every SO cubic feet. The entire area of the building should be 
calculated and not the space occupied by the seed only. As it costs 
as much to fumigate the air space as it does the seed, it is more eco- 
nomical to make the room only high enough for a person to stand 
comfortably. The size of the building needed can be calculated 
from the tons of seed to be fumigated, a ton of seed occupying 85 
cubic feet (2^ cubic meters). 
All water should be separated from the carbon disulphid and after 
the seed is in the house the disulphid poured into shallow vessels 
placed on top of the seed. Xot more than a pound should be placed 
in each vessel, so that it will evaporate quickly. Old gasoline cans 
cut down to about 3 inches high, or earthenware bowls, make good 
containers. The vessels should be scattered over the top of the 
seed pile and the disulphid poured into those farthest from the door 
first. There is no danger in doing this, but it is more convenient to 
have a number of half-inch pipes fitted with caps or corks extending 
through the walls and introduce the disulphid from the outside. As 
soon as the liquid is poured into the vessels the door should be closed 
and paper stuck over the cracks with flour paste. The house should 
be kept closed for at least 24 hours, and longer will do no harm, as 
continued exposure to the gas does not injure the germination of the 
seed. 
Planting Early Varieties. 
From the life history and feeding habits of the pink bollworm it 
can be readily seen that the later the cotton crop is in maturing the 
greater will be the amount of loss. Every cultural practice should 
be used in securing as early maturity as possible of the available 
cotton varieties. 
SUMMARY. 
The pink bollworm was introduced into Mexico in 1911 with seed 
for planting. Five years later it was generally and uniformly dis- 
tributed throughout the Laguna and had reached its maximum 
development. 
Infestation is started in the spring as soon as squares are formed. 
by moths emerging from hibernating larva?, and rapidly inere^s^ 
until practically every boll is infested with several larvae by fall. 
The life cycle is completed in an average of 31 days in the summer, 
but the larval stage of hibernating or resting larva? may be extended 
for 2 years or more. 
Dispersal is mainly through the carriage by man of hibernating 
larva? in seed, but local dispersion is brought about also by flight and 
carriage of adults. 
The pink bollworm causes approximately 25 per cent gross damage 
to the Laguna crop by feeding in the bolls and squares. This feeding 
results in a reduction in the quantity and quality of the lint pro- 
