RECENT STUDIES OF THE MEXICAN COTTON BOLL WEEVIL, 27 

 DEPENDENCE OF REPRODUCTION UPON FOOD. 



The studies of the feeding habits of the weevils in relation to mal- 

 vaceous plants other than cotton and Thurberia have served to throw 

 some further light on this subject. Many weevils were kept on cotton 

 leaves only from emergence to death, but only one pair was observed 

 in copula and not a single egg was found; but shortly after such 

 females were transferred to squares or bolls they would start ovi- 

 positing more or less normally. The possibility of the shape of the 

 square or boll being a mechanical stimulus to oviposition was con- 

 sidered for some time, but later in the season this idea was discarded. 

 A female which had been fed only on the blooms of Hibiscus syriacus 

 from emergence deposited a fertile egg on an open petal of a bloom. 

 Then shortly after this several females were observed to oviposit in 

 empty glass tubes. So it seems that oviposition is simply a question 

 of food and fertility, although the element or elements needed for 

 sexual maturity are not limited to cotton squares and bolls. This 

 element is evidently not present in cotton foliage in sufficient quanti- 

 ties, but is present in varying amounts in cotton squares, bolls, and 

 blooms, Hibiscus syriacus blooms, and also blooms of Callirrhoe 

 involucrata and 0, pedata. 



DEVELOPMENT. 



Only a few observations were made on the individual stages of 

 development, although much work was done upon the whole period of 

 development. The length of the stages was obtained by repeated 

 examinations to learn the dates of transformation. 



Incubation period. — The data on the egg stage are summarized in 

 Table XVII. 



Table XVII. — Incubation period of the boll weevil. 





Number 

 of indi- 

 viduals. 



Egg 



days. 



Period. 



Mean 



Date of oviposition. 



Mini- 

 mum. 



Maxi- 

 mum. 



Average. 



tempera- 

 ture. 



Deposited normally: 



Aug. 23 



9 

 8 

 20 

 17 

 11 

 23 

 24 

 9 

 17 



18 



17.6 

 53.8 

 48.28 

 55.0 

 131.1 

 139.2 

 50.4 

 81.6 



Days. 

 2 

 2 

 2 

 2 

 5 

 5 

 5 

 5 

 3.5 



Days. 

 2 

 3 

 3 

 4 

 5 

 6 

 6 

 6 

 5.5 



Days. 

 2.0 

 2.2 

 2.69 



2.84 



5.0 



5.7 



5.8 



5.6 



4.8 



°F 

 88.5 

 87.6 

 86.8 

 86.1 

 74.1 



24 



28 



29 



Sept. 19 



19 



20 



71 9 



21 





22.... 



72 9 







Total and average 



138 



594.9 



2 



6 



4.3 









Deposited externally: 



May 20 



1 

 2 



1 



4 



1 

 2 



1 



2 



1 

 2 



77.4 



Aug. 20 



86.4 







Total and average 



3 



5 



1 



2 



1.6 









