172 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 12 



tion. The field was planted to sweet potatoes in 1918. Fifty-one 

 volunteer plants were allowed to grow and develop bolls. These bolls 

 have been examined on five occasions very minutely by a group of the 

 most competent inspectors available, but no infestation has been 

 found. 



General Scouting in 1918 



An average of forty men were employed on the work of scouting 

 during the season of 1918. This work included the general vicinities 

 of the eleven mills which received Mexican seed in 1916, and a number 

 of places to which hulls or other more or less dangerous material were 

 shipped in 1916 prior to the time when the department took charge 

 and safeguarded the products. In a few cases hulls which may have 

 been infested were shipped to other states, such as Arkansas, Louisiana 

 and Mississippi. At the places where these hulls were received, inspec- 

 tions have been made similar to those in Texas. Likewise thorough 

 inspections have been made in some of the Eastern states which received 

 Mexican cotton in 1915. In all cases the inspections have yielded 

 absolutely negative results. 



It seems almost inconceivable that the pink bollworm has been 

 stamped out in the large territory which it was found to occupy in 

 southeastern Texas, but the thorough inspections which have been 

 made, including the examination of all the volunteer cotton plants, 

 indicate that if it has not been exterminated, it has been reduced very 

 close to the vanishing point. 



The reasons for this apparent success, which it is hoped will be found 

 real, are somewhat obscure. It is evident, however, that certain 

 factors operated in a very important way towards the results which 

 have been obtained. In the first place the work of cleaning the fields, 

 that is, burning all portions of the cotton plants which might carry 

 infestation, must have destroyed millions of the insects. That this 

 was the case is evident from the fact that in many localities during the 

 process of piUng the plants, a person could remove bolls from the plants 

 and in a few minutes find specimens of the pink bollworm. The 

 winter which followed this work of cleaning the fields was unusually 

 severe, bringing temperatures almost unprecedented in southeastern 

 Texas. This condition must have caused the death of many of the 

 larvae which, hidden in bolls covered with earth in footprints and 

 elsewhere, were missed by the laborers. At the same time it must not 

 be assumed that the low temperatures were responsible for killing all 

 of the insects which remained after the cleaning of the fields, since 

 specimens in perfect condition were found on a number of occasions 

 after the lowest temperatures had occurred. The last factor which 



