24 



BULLETIN IS 1 !, U. S. DEPARTMENT OF AGRICULTURE. 



In experiments made by the writer at Tampa, Fla., a total of 567 

 eggs was obtained from 21 females, or an average of 27 eggs each. 

 'The longest period of oviposition was 11 days. The largest num- 

 ber of eggs found in any one of 64 females dissected by Mr. S. E. 

 Crumb on August 3, 1911, was 22. 



At Clarksville, Tenn., the average number of eggs laid per female 

 during July, August, and September was 32, as shown by 63 separate 

 records. The longest period of oviposition was 21 days. Approxi- 

 mately 66 per cent of the eggs were laid during the first six days 

 after mating was observed. Each pair of beetles was kept in a 

 shell vial containing leaf tobacco. 



INFERTILE EGGS. 



Occasionally a female was found to lay infertile eggs, even after 

 mating. No eggs were obtained from unmated females. In one 

 -series of experiments, of a total of 182 eggs obtained from 24 different 

 females found in copula, 25 eggs, or 13.7 per cent, were infertile. 

 The eggs were deposited on leaf tobacco and kept at a temperature 

 of about 84° F., the daily variation being about 5°. This infer- 

 tility probably is much above the average, as hatching in many 

 other lots was almost perfect. The number of infertile eggs in 11 

 different lots, containing in all 773 eggs, was 30, or approximately 

 3.8 per cent. 



LENGTH OF DIFFERENT STAGES IN DEVELOPMENT OF INDIVIDUAL BEETLES. 



The following records from life-history studies made at Rich- 

 mond, Va., show the time required for each period of development 

 of different beetles from the egg to the adult. 



Table III. — Length of different stages in development of individual tobacco 

 beetles (Lasioderma serricorne) . Richmond, Va., 191If. 



Record No. 



Egg 

 laid— 



Hatched — 



Larva 

 formed 

 cell— 



Larva 



pu- 

 pated — 



Adult ap- 

 peared — 



Adult 



left 



cell- 



1 



July 1 

 ...do 



July 8 

 ...do 



Aug. 17 

 Aug. 19 

 Aug. 22 

 July 18 

 July 30 



Aug. 22 

 Aug. 23 

 Aug. 28 

 July 22 

 Aug. 3 



Aug. 29 

 Sept. 1 

 Sept. 4 

 July 29 

 Aug. 9 



Sept. 6 



Sept. 5 

 Sept. 9 



2.. 



3 



July 5 

 June 1 

 June 18 



July 12 

 June 7 

 June 25 



4 



Aug. 2 





Aug. 16 



Record No. 



Mated — 



Eggs 

 laid— 



Food. 



Egg to 

 beetle. 



Egg to 

 egg. 



1 



Sept. 9 

 Sept. 7 

 Sept. 10 

 Aug. 6 

 Aug. 21 



Sept. 11 

 Sept. 10 

 Sept. 17 

 Aug. 9 

 Aug. 24 



Tobacco 

 ..do... 





Days. 

 59 

 62 

 61 

 58 

 52 



Days. 

 72 



2 





71 



3 



...do... 



74 



4 



.do. . 



69 



6 



. do. 



67 









