36 CIRCULAR 4 2 2, U. S. 'DEPARTMENT OF AGRICULTURE 



houses. In the United States for the last 15 years there has been an 

 ever-increasing concentration of tobaccos held for long periods in 

 storage, and the only practical solution of the insect problem under 

 these conditions is periodic controls applied in the warehouses. 



Specialized fumigation apparatus is being adapted for use in to- 

 bacco factories, in treating both unmanufactured tobaccos and manu- 

 factured products. A number of fumigants have been tested for use 

 in partial vacuum and at atmospheric pressure, the most satisfactory 

 of which were mixtures of ethylene oxide, 1 part, and carbon dioxide,- 

 9 parts; methyl formate, 15 percent, and carbon dioxide, 85 percent; 

 and hydrocyanic acid. 



The most promising type of specialized apparatus for tobacco 

 fumigation consists of vacuum chambers. These are steel tanks con- 

 structed of the proper size to accommodate the load to be fumigated. 

 Considerable quantities of unmanufactured cigar tobaccos, Turkish- 

 type tobaccos, and manufactured tobacco products are being fumi- 

 gated in these tanks. The chambers are filled with tobacco, and then 

 the air is removed by a pump until a reading of 29 inches or slightly 

 above is recorded on a mercury gage. The fumigant is then ad- 

 mitted, and satisfactory results are usually obtained, when the tem- 

 perature of the tobacco is above 70° F., with an exposure of 3% to 4 

 hours. Additional research must be carried out in this field of fumi- 

 gation before recommendations are available. 



SUMMARY 



This circular includes the most important observations and studies 

 made of the tobacco moth (Ephestia elutella) at Richmond, Va., from 

 1931 to 1934. 



A review of the literature on the history and distribution of the 

 moth shows it to be a general feeder on dried vegetable products, but 

 the writers assume that unknown factors in the biology have pre- 

 vented the insect from assuming greater importance as a stored- 

 product pest. 



The moth was first recorded as a pest of tobacco in Crimea in 1913 

 and has since appeared infesting cigarette types of tobaccos in Bul- 

 garia, Greece, Turkey, Rhodesia, England, Poland, and the United 

 States. 



The injury to cured tobacco is inflicted by the larvae of the moth. 

 Often the entire leaf is consumed with the exception of the larger 

 veins — a type of feeding resembling that of many species of leaf- 

 eating caterpillars. The webbing made by the nearly mature larvae 

 often gives infested tobacco an unsightly appearance. 



The larvae were observed to attack most severely those grades of 

 tobacco that contained the highest percentages of sugar in the leaf, 

 which include the higher priced commercial grades of the flue-cured 

 type. 



Life-history studies made during 1932 and 1933 show that under 

 the usual conditions of temperature and moisture prevailing in Vir- 

 ginia and North Carolina three broods of moths appear during the 

 period April 24 to October 31. Larvae of three generations are 

 produced each year. A small percentage of the first generation, 

 approximately 50 percent of the second, and all of the third over- 

 winter as larvae to emerge the next year as the spring brood of moths. 



