10 



FARMERS BULLETIN 848. 



Fig. 2.— Cotton boll weevil: a, Beetle, from above; 

 6, same, from side. About five times natural 



this passes to a gray or nearly black shade in a few weeks' time. 

 The general appearance of the insect ^^dll be evident from the accom- 

 panying illustration (fig. 2). 



Many insects resemble the boll weevil more or less closely. In 

 fact, there are hundreds of species of weevils in this country that 

 may be easily mistaken for the enemy of cotton. Many erroneous 



reports about the occurrence of 

 weevils far outside of the infested 



\^'"^"f'''^''^ / \ / ^^^^ have been due to this simi- 



M. if ^'^^C larity. The only safe -way to de- 



I *^^lv termine whether any insect is the 



boll weevil is to send it to an en- 

 tomologist for examination. In 

 the field the most conspicuous in- 

 dication" of the presence of the 

 boll weevil is the flaiing (fig. 4) 

 and falling of great numbers of 

 squares. Unfavorable climatic 

 conditions and careless cultiva- 

 tion, however, frequently cause 

 great shedding. If excessive 

 shedding be noticed, and the squares upon being cut open show a 

 white, curved grub (fig. 5) that has fed upon the contents, there is 

 little doubt that the boll weevil is the insect causing the damage. 



The boll weevil passes the winter in the adult stage; that is, as a 

 beetle. In the sprmg and throughout the fniiting season of cotton 

 the eggs are deposited by the female weevils in cavities formed by 

 eating into the fruit of the plant (see fig. 4). An egg hatches under 

 normal conditions m about three days, 

 and the grub immediately begms to 

 feed. In from 7 to 12 days the larva 

 or grab (fig. 3, at left) passes into 

 its pupa stage (fig. 5, at right), corre- 

 sponding to the cocoon of butterflies 

 and moths. This stage lasts from 

 three to five days. Then the adult 

 issues, and in about five days begins 

 the production of another generation. 

 Climatic conditions cause considerable variation in the duration oi 

 the stages, but on an average it requires from two to three weeks 

 for the weevil to develop from the egg to the adidt. Males and fe- 

 males are produced in about equal numbers. The males feed uponl 

 the squares and bolls without moving until the food begins to dete- 

 riorate. The females refrain from depositing in squares visited by 

 other females. This applies throughout most of the season, but late 



Fig. 3.— Cotton boll weevil : Larva st left, 

 pupa at right. About five times natural 

 size. 



