PINK bollworm OF COTTON IN MEXICO. 35 



DISPERSAL. 



The most important factor in the dispersal of the species is man. 

 By his transportation of cotton seed and cotton products he has car- 

 ried the insect from its original home to all parts of the cotton-produc- 

 ing world. Once it is established, local dispersal from one field to 

 another is also by flight, and in some instances the carriage of the 

 larvae by water is of importance. 



CARRIAGE OF LARVAE IN SEED FOR PLANTING AND OTHER PURPOSES. 



The transportation of infested seed by man from place to place is 

 the usual means by which this insect is carried to new localities. It 

 was introduced into Mexico in 1911 with seed for planting; into 

 Brazil in 1911-1913 with seed for planting; and more recently into 

 certain parts of Texas with seed in cotton and seed for milling pur- 

 poses. From what has already been stated concerning the habits 

 of the pink bollworm, it is evident that seed from an infested field is 

 sure to contain a certain percentage of infestation, and it is known 

 that the resting larvse can live for at least 2 years in such seed. It is 

 thus seen that the larvse are admirably adapted for transportation 

 over great distances in this way. Seed, moreover, is often inci- 

 dentally carried with other products. Railroad cars which have 

 been used for shipping cotton seed are a very dangerous example of 

 this. Seed will usually be found in the cracks and corners and be- 

 tween the walls of the car. Numerous instances of this have been 

 noted, particularly by inspectors at border points, where live pink- 

 bollworm larvae were taken from cars which had been used for seed in 

 the Laguna district and later used for exportation of other products. 

 Bales of cotton often carry seed and as many as several hundred seeds 

 have been found mixed with the lint and attached to the bagging. 

 Cotton waste and used cotton bagging are other items usually having 

 seed attached to them. Cotton pickers in Mexico often move from 

 plantation to plantation. It is a common practice with them to carry 

 their own picking sacks and among their belongings seed cotton and 

 cotton seed are often found. These and similar practices are common 

 means by which the insect is carried. 



FLIGHT AND CARRIAGE OF ADULTS. 



While the moth of the pink bollworm is small, it has ample wing 

 power for its size and is capable of quick, darting flight. When 

 disturbed during the day it flies only a short distance and hides 

 under the nearest object. On the other hand, several hundred 

 moths were liberated on top of the house where a light breeze was 

 blowing, in the morning and at dusk. About half of those liberated 

 in the morning flew only a few feet before settling down, while the 

 others flew upward and away as far as the eye could follow them. 

 Those liberated at dusk nearly all flew upward and away till lost to 

 sight. In all cases they flew with the wind and not quartering to it, 

 as some insects do. Up to the present time no conclusive data have 



