30 BULLETIN 737, U. S. DEPARTMENT OP AGRICULTURE. 



In addition to the insects already mentioned the following species 

 have been found frequenting cured tobacco: Trogoderma tarsale 

 Melsheimer, Attagenus piceus Olivier, Tenebrioides mauritanica 

 Linnaeus, Mezium americanum Laporte. Catorama impressifrons 

 Fall and Attagenus piceus Olivier have been recorded by Morgan 

 (TO) as infesting tobacco seed. Mezium americanum Laporte (PL 

 III, fig. 3) has been found breeding in tobacco seed by Mr. S. E. 

 Crumb of the Bureau of Entomology. 



NATURAL CONTROL. 



Numerous natural agencies are concerned in the control of the 

 tobacco beetle. These forces, singly or combined, serve to keep the 

 insect in check. 



CLIMATIC CONTROL. 



In the temperate zones, at least, the most important factor in 

 holding the beetle in check is the cold of winter. Under ordinary 

 conditions in cool climates their activities are confined to about one- 

 half of the year. A comparatively small proportion of the insects 

 survive the winter when exposed to even moderate cold if it is long 

 continued, or to sudden abnormal changes of temperature. Severe 

 freezing at temperatures lower than 10° F., if continued even for a 

 short time, will result in extermination. At different times in order 

 to determine the effect of exposure to variations of temperature in 

 unheated buildings, heavily infested cans of smoking tobacco were 

 wrapped in paper and kept over winter in various localities. The 

 records obtained are as follows: 



AT APPOMATOX, VA., WINTER OF 1910-11. 



About 10 pounds of pressed plug and granulated smoking to- 

 bacco heavily infested were placed in original packages, in a large 

 pasteboard box, wrapped with paper, and kept in an unheated 

 room. A self-registering thermometer in the package showed that 

 the lowest temperature reached was 11° F. Practically out-of-door 

 conditions were experienced from December, 1910, until April, 1911. 

 The beetles were exterminated. The tobacco was kept for several 

 months but did not show signs of reinfestation. 



AT RICHMOND, VA., WINTER OF 1913-14. 



Two 5-pound packages of infested smoking tobacco were wrapped 

 in paper. One package was placed in an unheated cellar, the other 

 in a partly open building giving approximately out-of-door tempera- 

 ture variations. Both lots of tobacco were heavily infested. The 



