8 



CIRCULAR 8 6 9, U. S. DEPARTMENT OF AGRICULTURE 



Richmond area emergence of the spring brood is usually at a peak 

 in the last 2 weeks of May. The population of moths in a warehouse 

 then declines, reaching a very low ebb early in July. A second peak 

 of emergence occurs in August, and a third and usually much smaller 

 peak is often noted late in September or in October (fig. 5) . In 1918 

 and 194-9 a full third brood occurred, and at Norfolk, Va., active moths 

 were noted as late as the middle of December. 





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Figure 5. — Seasonal occurrence of the tobacco moth in Virginia and North Carolina. 



Habits 



The tobacco moth feeds on tobacco only in its larval stage. It does 

 not attack manufactured tobacco products. Attack is confined to leaf 

 tobacco of the flue-cured and Turkish types, preferably of the better 

 grades — those high in sugar and low in nicotine. Tobacco with a sugar 

 content (dextrose before inversion) of more than 10 percent (much 

 flue-cured tobacco contains 20 percent or more of sugar) and a nicotine 

 content of less than 2 percent seems particularly favored. 



This insect is a heavier feeder than the cigarette beetle ; in a severe 

 infestation it devours many leaves completely except for the midrib 

 and larger veins (fig. 6). In feeding, the larva leaves behind a silken 

 thread that forms a webbing and catches pellets of excrement. Such 

 accumulations of webbing and excrement are unsightly and objection- 

 able to buyers and manufacturers. 



Mature larvae move out of the tobacco, or at least to the surface — 

 a necessary migration, because the soft, fragile adult moth could not 

 cut its way out of confinement. It is often trapped when attempting 

 to crawl through very tiny openings. The moth apparently does not 

 mate in close confinement ,"and so emergence is necessary before fertile 

 eggs can be laid. 



The tobacco moth feeds on many stored products besides tobacco. 

 In the United States it has been found in almost all grains, as well as 

 in peas, beans, corn meal, wheat flour, rolled oats, peanut meal, poultry 

 laving mash, stock feed, and various cereal products. It has also been 

 reported as infesting cacao beans, chocolate, shelled nuts, linseed meal, 

 coffee, chicory, ship's biscuits, cottonseed cake, cayenne pepper, rice, 

 pearl barley, and other seeds. 



