BIOLOGY OF TOBACCO MOTH AND ITS CONTROL 37 



The temperature was considerably higher in 1933 than in 1932, and 

 this was reflected in the more rapid development of the larvae and 

 pupae, but it did not appear to affect materially the average incuba- 

 tion period of eggs or the average length of adult life. Spring-brood 

 emergence began on April 21 in 1932 and on April 14 in 1933. Some 

 larvae which emerged as spring-brood moths in 1933 had required 

 more than a year to complete development, the maximum being 380 

 days. 



Records of oviposit km and longevity of 105 pairs of moths show 

 that the greatest number of eggs obtained from one female was 260, 

 and the maximum longevity of adults was that of a female in 1933 

 that lived 25 days. 



The maximum and minimum periods consumed in developing 

 through the egg, larval, and pupal stages are summarized and dis- 

 cussed. The uneven rate of growth of larvae caused an overlapping 

 of generations, and it was concluded that this great variation could 

 not be satisfactorily explained on the basis of temperature and qual- 

 ity of food. The higher temperatures prevailing in 1933 caused a 

 more rapid growth of larvae, permitting 84 second-generation indi- 

 viduals to complete growth, whereas in 1932 only 5 completed growth. 



The natural enemies of the tobacco moth are a small braconicl para- 

 site, Microbracon hebetor, which attacks well-grown larvae; a mite 

 of the genus Laelaps, predacious on adults; and a spider, Theridwn 

 tepid ariorwm, which destroys hundreds of adults. None of these 

 natural enemies exert effective control of moth infestations in 

 warehouses. 



Periodic atmospheric fumigation of tobacco warehouses of the 

 closed type proved effective in 1932. A dosage of 10 ounces of hydro- 

 cyanic acid per 1,000 cubic feet of storage space was used. Four 

 fumigations were carried out between June 1 and September 8 at an 

 average total cost of 61.2 cents per 1,000 cubic feet fumigated and 

 an average cost of 9.8 cents per hogshead of tobacco. 



Recommendations are given for the periodic fumigation of tobacco 

 warehouses, and the results of experiments in sealing closed-type 

 storages are presented. 



The importance of using every known safeguard to protect life and 

 property during fumigation is emphasized. 



LITERATURE CITED 



(1) Back. E. A., and Cotton, R. T. 



1935. INDUSTRIAL FUMIGATION AGAINST INSECTS. U. S. Dept. Agr. CilC 



369, 52 pp., illus. 



(2) ■ and Reed, W. D. 



1930. EPHESTIA ELUTELLA HUBNER, A NEW PEST OF CURED TOBACCO IN THE 



united states. Jour. Econ. Ent. 23 : 1004-1006. 



(3) Bovingdon, H. H. S. 



1931. PESTS IN CUBED TOBACCO. THE TOBACCO BEETLE, LASIODERMA SERRI- 



CORNE FAB. AND THE CACAO MOTH, EPHESTIA ELUTELLA HB. To- 



bacco, no. 608, pp. 56-59, illus. London. 

 14) 



1933. REPORT ON THE INFESTATION OF CURED TOBACCO IN LONDON BY THE 



cacao moth ephestia elutella hb. Gt. Brit. Empire Marketing 

 Bd. Bull. 67, 92 pp., illus. 

 (5) Chittenden, F. H. 



1897. some little-known insects affecting stored vegetable products : 



A COLLECTION OF ARTICLES DETAILING CERTAIN ORIGINAL OBSERVA- 

 TIONS made upon insects of this class. U. S. Dept. Agr., Div. 

 Ent. Bull. (n. s.) 8, 45 pp., illus. 



