50 



BULLETIN 737, U. S. DEPARTMENT OF AGRICULTURE. 



more effective if the sheets of fly paper are pinned so that the surface 

 on both the inside and outside of the cylinder is sticky. Traps of 

 this type operated in a large tobacco warehouse were under observa- 

 tion for some time and were found to destroy large numbers of 

 beetles (fig. 13). Another form of trap consists of a large globe, 

 such as is used for street lights, placed over a funnel, the lower part 

 of the spout of the funnel opening into a cyanid jar in which the 

 beetles are killed. An electric-light bulb can be used in the globe, 

 or a trap light of the same type can be operated with acetjdene or 

 other light. Another method of destroying the beetles consists of 



placing shallow pans of 

 oil underneath the lights. 

 A heavy odorless oil is 

 best for this purpose in 

 ca.se leaf tobacco, which 

 may take up odors of kero- 

 sene or other oils, is stored 

 near by. The traps fitted 

 with cylinders of fly paper 

 will perhaps be found best 

 adapted to most condi- 

 tions. While adults fly 

 mere readily toward blue 

 or blue-violet light than 

 toward red or orange, col- 

 ored light bulbs or colored 

 screens cut down the in- 

 tensity of a source of light. 

 Ordinary electric-light bulbs of clear glass of the nitrogen-filled and 

 other types which transmit lights rich in rays of short wave length 

 have been found well adapted to trapping. 



Sex of beetles collected at light. — A sheet of sticky fly paper which 

 had been suspended around an electric light in a tobacco warehouse 

 at Danville, Va., in July, 1911, was examined by Mr. S. E. Crumb. Of 

 100 beetles that were removed and dissected, 36 were males and 64 fe- 

 males. Four females contained, respectively, 2, 2, 17, and 22 mature 

 eggs. Seventeen females contained immature eggs, half developed or 

 more, as follows: 2, 2, 2, 2, 3, 3, 4, 5, 6, 7, 7, 8, 10, 10, 11, 12, and 36. 

 Forty-three females were without eggs. Approximately 32 per cent of 

 the females contained eggs and 68 per cent of the females did not. 



COLLECTING AT WINDOWS. 



As the light becomes dim in late afternoon in infested warehouses 

 or factories the adult tobacco beetles fly to the windows, often col- 

 lecting in large numbers cm the glass and casings. The beetles may 



Fig. 13. — Arrangement for using sticky fly paper in 

 collecting adults of the tobacco beetle in ware- 

 houses. 



