February, '22J cotton states entomologists proceedings 109 



work should be followed up for two or three years following, using about yi the number 

 of cans used in the first campaign. Complete eradication is considered entirely 

 possible. The best can used for the syrup is the stock shrimp can holding about 6 

 ozs. They are bought with special lids. 



In scouting for the Argentine ant first look around in the wholesale districts where 

 freight is being loaded and unloaded. Then look at trees. Trees in infested areas 

 can usually be seen 16 to 18 feet away by one who has a trained eye. They are 

 usually badly infested with scale insects and the characteristic movements 

 of the ants can be observed. Mr. Bishopp says that the Argentine ant has a character- 

 istic odor and this was confirmed by Mr. Kimball. When the edge of the infested 

 area has been found it is an easy matter to trace out the area. 



Fully one-half of successful eradication depends upon the preparation of the syrup • 

 An ordinary druggist cannot be depended upon and even a chemist is likely to be care- 

 less. Syrup is being made for New Orleans, Baton Rouge and other southern cities under 

 Mr. Barber's supervision and can probably be purchased for about 65c a gallon. 

 A number of firms have been making ant syrup, charging as high as $3.00 a gallon for 

 it, but their products are not dependable. 



Campaigns have often been discourged by local druggists and others who have 

 been making money in the sale of proprietary compounds and they have dissemi- 

 nated propaganda stating that children have been poisoned by the syrup. In con- 

 ducting eradication campaigns this sort of propaganda should be headed off and 

 the methods of eradication discussed carefully in advance. 



Cotton Seed Sterilization {Afternoon Session) 



Cotton seed sterilization, according to Mr. R. E. MacDonald, should be put into 

 practice by every southern state as an added precaution against the spread of the 

 pink bollworm. It is believed that sterilization can be developed to the point 

 where practically 100% of the worms can be killed; 98% of the worms are being 

 killed with seed temperature at 130° F. 



Mr. MacDonald's figures were based on investigations which he had conducted 

 and on investigations which were conducted by the Bureau. It was found that seed 

 could be heated to a temperature of 170°F. and held at that temperature for an hour 

 without hurting the seed. Moreover the heat treatment apparently improved 

 the germinating quality of the seed. Egyptian workers consider that 162° F. is a 

 safe temperature for seed. 



It was found that the thermal death point of Pectinophora larvae was between 130 

 and 145° F. 



130° F. for 45 min. killed 100% 



130° F. for 30 min. killed 62.5% 



135° F. for 35 min. killed 100%o 



140° F. for 20 min. killed 100%o 



145° F. for 10 min. killed 100%o 



The above temperatures are the temperatures which the seed mass actually reached. 

 To attain these temperatures it was of course necessary to have the oven much hotter 

 as heat penetrates the seed mass very slowly. This was thoroughly demonstrated 

 by MacDonald in a number of experiments. It was found that with the temperature 

 of the oven at 239°F. it took five minutes to raise the temperature of the seed mass, 

 two inches deep, from 73° F. to 82° F. With the oven at 275° F. it requred 45 

 minutes to raise the temperature of the seed mass at four inches deep from 73° F. 

 to 140° F. 



To heat effectively a machine must be devised which will keep the seed stirred up 

 so that the seeds will be isolated one from the other and which will heat the seed to 

 the required temperature in not more than about five minutes. A sterilization 

 apparatus requiring longer than this would not be practicable. The sterilizer must 

 be carried as a continuous process of ginning. In the sterilizers which it is planned 

 to put in effect in Texas the seed will be heated to much higher temperatures than 

 is done in Egypt. The seed mass when it leaves the machine should be about 140° 

 F. In addition to the high oven temperature the seed will be subject to a continuous 

 and somewhat protracted high temperature on account of massing and retaining 

 the heat after it leaves the oven because of the numerous air spaces between the 

 fibers. 



