132 



frequent attempts are made at eating, and the larvae would be readily 

 poisoned if poisons were present on the plants. From a series of 

 observations, both in 1903 and 1901, it was found that from 62 to 73 

 per cent of the eggs deposited by the bollworm moth on cotton were 

 placed on the leaves, stems, leaf stalks, etc., or on other parts than 

 the tender tips, squares, and flowers, so that the resulting larvae 

 could be destro3^ed b}^ timely applications of poison. Ordinarily, 

 poisons will be profitable onl}- against the August generation of 

 larvae, and results will be much more pronounced during seasons of 

 severe, as compared with moderate, bollworm injurj^ The plants 

 should be kept poisoned from about the last week in July until about 

 the second week in August, and later if the moths are seen to be 

 abundant. During this period the eggs of the destructive August 

 brood will be deposited, and the presence of poisons on the plants as 

 the young larvae are hatching will result in their destruction in large 

 numbers. 



As between the dusting and spra3dng methods of applying poison, 

 the former seems more practicable (see PL XXIII, fig. 1). In dusting 

 with Paris green, this should be used at about the rate of 2 to 3 pounds 

 per acre for each application, the quantity var34ng somewhat with the 

 size of the plants. In man}" cases, as with careless labor, it will be 

 more economical to dilute the poison with cheap flour or dry slaked 

 lime. Applications may satisfactorily be made by the usual pole 

 and bag method. The use of geared poison blowers (see PL XXIV, 

 fig. 1) would permit of the work being done more rapidl}^, which is 

 very important. Applications of dr}" poison should be made at night, 

 early in the morning, or late in the evening, when the plants are 

 sufficiently wet with dew to insure its sticking. Paris green, applied 

 in water, should be used at about the rate of 1 pound to 50 gallons, 

 which amount will cover about 1 acre (see PL XXIII, fig. 2, illus- 

 trating Department's spra3dng experiments in bollworm control). The 

 efiect of a rain will be to wash the poison largely from the plants, and 

 the application must necessaril}^ be at once repeated. Applications of 

 poisons, as above indicated, at intervals of a week or ten days, should 

 keep the plants sufficiently^ poisoned to accomplish the desired results. 



INEFFECTIVE METHODS OF COMBATING THE BOLLWORM. 



During periods of serious bollworm injury planters often resort to 

 various methods in their efforts to prevent the destruction of the crop. 

 The burning of lights in the fields, the use of poisoned sweets, and the 

 burning of sulphur were more or less practiced in 1903. These and 

 similar methods have been shown, b}" numerous tests (see PL XXV, 

 figs. 1 and 2) during the present investigation, to be of no practical 

 value whatever, and attention is called to their futilit}" that needless 

 expense may be avoided in the future. 



