91 



manifested in various directions and so produce various results in 

 form, habitat, habits, etc. Undoubtedly the boll weevil is now chang- 

 ing in adaptation to a climate quite different from that in which the 

 original species was produced. It has become also highly specialized 

 as to food, having so far as we can learn but a single food plant— cotton. 

 It is a fair question, therefore, to consider whether it has changed in 

 its essential relations to the fruit of this plant since it first began to 

 appear upon it. 



When lirst reported to the Department of Agriculture as an inju- 

 rious insect (see footnote, p. 17) the specimens of the weevil were bred 

 from the bolls of cotton. As conditions are now found in Texas, by 

 far the major part of the weevils are developed in squares. It is a 

 question of interest, therefore, whether the predominant original habit 

 was to breed in bolls or in the squares of cotton. An examination of 

 the breeding habits of other species of the genus Anthonomus shows 

 that there is a great diversity of habit in this respect. A comparison 

 of the length of the period of development in squares and bolls shows 

 that in bolls the period ma}^ be fully three times as great as it is in 

 squares. Is the longer or the shorter period of development the more 

 normal? Comparison with other species of the genus indicates that 

 the longer period is more typical and therefore more original. The 

 Axry short period of development in squares and small bolls has 

 resulted from an adaptation to the reduced food suppl}^, which in 

 squares especially is limited in quantity and of a very perishable 

 nature. The general conclusions from these considerations would 

 indicate that originally this species bred principally upon the bolls and 

 had few generations in a season, but through gradual adaptation to 

 changed conditions in the growth of the cotton plant the weevil has 

 now come to develop mostly upon the squares, thus producing many 

 generations in a season and greatly increasing the capacity of the pest 

 for serious injury. 



DOES PARTHENOGENESIS OCCUR? 



To test the possibility of weevils reproducing parthenogenetically 

 about 40 individuals were isolated from the very beginning of their 

 adult life. Each beetle was supplied daily with fresh, clean squares and 

 careful watch was kept for eggs. The first noticeable point was that 

 no eggs were found till the weevils were about tv/ice as old as females 

 usually are when they deposit their first eggs. After the}^ began to 

 oviposit, it was found that a very small proportion of the eggs w^ere 

 deposited in the usual manner within sealed cavities in the squares, 

 but nearly all of them had been left on the surface, usuall}^ near 

 the opening to an empty eg;g puncture. This same habit was shown 

 by a number of females, and so can not be ascribed to the possible 

 physical weakness of the individuals tested. The number of eggs 



