56 BULLETIN 918, U. S. DEPARTMENT OF AGRICULTURE. 



for every 80 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. Not 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 larvae, and rapidly increases 

 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 larvae may be extended 

 for 2 years or more. 



Dispersal is mainly through the carriage by man of hibernating 

 larvae 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- 



