THE TOBACCO BEETLE. 21 



death when disturbed, the head and thorax being bent downward 

 and the legs drawn closely together. 



The adults generally begin to mate the second or third day after 

 leaving the vicinity of the pupal cell. Mating in some cases occurred 

 the first day, and was observed to take place several times during 

 the egg-laying period. 



PROPORTION OF SEXES. 



The proportion of females seems to be somewhat greater than that 

 of the males. Four lots which had emerged at different times from 

 material kept at the laboratory gave a total of 36 males and 41 

 females. One hundred beetles collected at lights at a tobacco ware- 

 house at Danville, Va., were dissected by Mr. S. E. Crumb, of the 

 Bureau of Entomology, and of these 36 were' males and 64 females. 



LENGTH OF THE ADULT STAGE. 



The length of life of the adults depends largely upon the tem- 

 perature after emergence. In summer, or in rooms kept constantly 

 warm, the beetles die much sooner than do those which emerge dur- 

 ing cool weather. Normally the adults die in from 3 to 6 weeks after 

 emergence. Although the mouth parts and digestive tract of the 

 adult beetle apparently are complete and they are capable of gnaw- 

 ing through tobacco or other food substances to escape from the 

 locality of the pupal cell, little if any evidence of feeding has been 

 observed. Large numbers of adults', directly after emergence, were 

 put in sealed tubes containing cigars, the open ends of the cigars 

 being sealed to prevent entrance of the beetles. Several cigars pre- 

 pared in this manner were kept until all adults had died, but no signs 

 of feeding or injury to the cigars could be seen. Other beetles were 

 kept in test tubes with small bits of leaf tobacco. In a few tubes the 

 edges of the leaf had been slightly gnawed and fine particles of the 

 leaf were found. Beetles confined in tubes closed with cork stoppers 

 frequently gnaw into the cork for a short distance. No evidence has 

 been secured to show that cigars or tobacco are directly injured by the 

 adult or beetle except when burrowing out after transforming from 

 the pupa stage. Eggs are deposited and the adults apparently live 

 the normal length of time whether food is present or not. At Clarks- 

 ville, Tenn., a number of experiments were made by Mr. K. B. Mc- 

 Kinney and the writer to determine whether the presence of food has 

 any bearing on egg deposition or length of life of the adults. A brief 

 summary of the results obtained in one series of experiments 



