618 ANNUAL, REPORTS OF DEPARTMENT OF AGRICULTURE. 



to the pink bollworm. The indication obtained in previous work 

 that a considerable number of larvae can be killed by the applica- 

 tion of poison was followed up with detailed tests in the field and 

 laboratory. Different poisons were used and different methods of 

 application tested. A very noticeable degree of reduction in the 

 number of larvae in the bolls was obtained, but many details remain 

 to be worked out before a decision can be reached as to the prac- 

 tical usefulness of poisons. It is safe to say, however, that the 

 indications for a successful outcome are at least as good as they 

 were in the case of the cotton boll weevil as recently as eight years 

 ago. The amount of control of the insect which can be secured 

 through different methods • of tillage and different systems of 

 handling the water for irrigation was studied. On account of the 

 seasonal and other variations from year to year, it is necessary to 

 continue work of this kind for a series of years before exact knowl- 

 edge is gained. Other lines of observation dealt with the distance 

 of flight of the pink bollworm moth, the condition under which 

 plants other than cotton are attacked, the thermal death point of 

 larvae, and the effect of conditions of seed storage on larvae longevity. 

 A bulletin dealing with the results -obtained has been submitted for 

 publication. 



MEXICAN BORDER CONTROL. 



The border control to prevent the reentry of the pink bollworm 

 from Mexico into the cotton fields of the South has been continued 

 on the Texas-Mexican border. This service was organized primarily 

 to safeguard the cotton industry, but the inspectors also assist in 

 enforcing all quarantines which relate to plants and plant products, 

 the entry of which from Mexico is prohibited or regulated. 



During the fiscal year ending June 30. 1923, 23,132 freight cars 

 were inspected on the Mexican side of the border for cottonseed, 

 and of this number 13,719 were fumigated in houses constructed 

 for the purpose as a condition of entry by representatives of the 

 board. Fumigation fees amounting to $54,128 were collected and 

 turned into the Treasury. At Del Rio, where there are no rail- 

 roads entering Mexico, 23,694 vehicles crossing the border were 

 inspected. Fifty-two of these vehicles were found to be con- 

 taminated with cottonseed and after a thorough cleaning were, as 

 an additional precaution, fumigated, for which fees amounting to 

 $26 were collected and turned into the Treasury. 



A fire originating in the tanks of a local oil company on July 19, 

 1922, resulted in the total destruction of the 15-car fumigation 

 house located at Laredo, Tex. In the absence of a fumigation 

 house, it was necessary to fumigate the interior of all box cars and 

 to spray all flat cars and gondolas. In view of the increase in the 

 number of cars crossing the border at this point during the fiscal 

 year 1922, it was deemed desirable to construct a 20-car house. 

 This house was completed at a cost of approximately $45,000 and 

 put into operation on May 4, 1923. 



As in the past, inspectors of the Federal Horticultural Board have 

 been cooperating with customs officials in the inspection at foot- 

 bridges to prevent the entry of contraband plants and plant products. 

 This cooperation exists at Brownsville, Laredo, Eagle Pass, Del 



