FIELD CROP INSECTS 259 



ing their juices. They are strong fliers and the later broods 

 are often carried northward by the winds in large numbers, 

 even as far as Canada. The moths of the first generation 

 in the spring fly northward, and from eggs deposited by 

 them another generation develops in due time, which, in 

 turn, flies northward, and thus by late summer the worms 

 are found throughout the whole cotton belt. At least seven 

 generations occur along the Gulf Coast and three at the 

 northern limit of cotton growth. Considering the number 

 of eggs laid by each female, it is evident that the species will 

 multiply very rapidly, and it has been estimated that the 

 progeny of one moth, if there were no mortality, would 

 amount to over 300,000,000,000 individuals after four gen- 

 erations, which, if placed end to end, would encircle the 

 earth at the equator over four times. 



The usual remedy has been to dust the plants with Paris 

 green. Powdered arsenate of lead would, undoubtedly, be 

 as effective. Dusting machines which will cover four rows 

 at once have been in common use where injury is frequent. 

 It may also be applied with powder guns. It has most com- 

 monly been distributed by being shaken from bags fastened 

 at the ends of a pole and carried by a man on horseback. 



144. The Mexican Cotton Boll Weevil * (20). Probably 

 no one insect has been so seriously and continuously injuri- 

 ous over so large a section of country as the boll weevil. As 

 its name indicates, it is a native of Mexico, whence it spread 

 into Texas about 1890. Since then it has spread steadily east- 

 ward until it now inhabits nearly all of the cotton belt west of 

 Georgia, and in the course of another decade, will, doubt- 

 less, cover the Eastern Cotton States. In 1904 the writer 

 made a careful estimate of the loss caused by the boll weevil 

 in Texas, which showed that it amounted to $25,000,000 

 * Anthonomus grandis Boh. Family Curculionidce. 



