THE TOBACCO SPLITWOKM. 



As in the case of the larvge, the pupae of the habitual potato 

 feeder are larger than those from the habitual tobacco feeder and the 

 maximum measurements in the foregoing description are from 

 potato-reared pupae. 



The adult is a slender, inconspicuous moth with dark grayish wings 



bearing indefinite yellowish streaks and having an expanse of about 



20 mm. 



LIFE HISTORY. 



At ClarksviUe, Tenn., the sphtworm requires 25 to 30 days in sum- 

 mer for completing its development from egg to adult. Of this time 4 

 days are spent in the egg stage, 15 to 17 days in the larval stage, and 

 6 to 9 days in the pupal stage. The length of these stages is consid- 

 erably affected by temperature, as is indicated in detail in the accom- 

 panying tables. By reference to Table III we see that at an average 

 mean temperature of about 81° to 82° F. the minimum pupal period 

 is obtained, and that when the average mean temperature falls below 

 about 68° to 70° F. the pupal period is very greatly lengthened. 



Eggs are deposited singly upon the foliage of the host plant. 

 Moths begin to oviposit two or three days after emergence and con- 

 tinue ovipositing for several nights. The largest number of eggs 

 obtained from a single moth was 46, but this probably does not 

 represent the maximum oviposition under normal conditions. 



The larva is very active, is capable of prolonged exertion imme- 

 diately after hatching, and clings very tenaciously to the foliage. 

 The frass is either stored in a particular part of the mine or is cast 

 outside whore, in the case of those working upon potato tubers, it 

 forms masses held together by silk. The larva pupates in a shght but 

 somewhat tough cocoon of silk and debris among clods or rubbish at 

 or near the surface of the soil. 



Table I.- — Length of egg stage of tobacco splitworm. 



Eggs deposited 

 night of— 



Eggs batched 

 night of— 



Egg 

 stage. 



Average 

 mean 



tempera- 

 ture. 



June 15,1910 

 June 17,1910 

 June 22,1910 

 July 3, 1913 

 July 3, 1913 

 July 4, 1913 

 July 5, 1913 

 Aug. 5,1913 

 Aug. 6,1913 

 Aug. 21,1913 

 Sept. 11, 1913 

 Sept. 12, 1913 



June 19,1910 

 June 21,1910 

 June 27,1910 

 July 7, 1913 

 July 7, 1913 

 July 8, 1913 

 July 9, 1913 

 Aug. 8, 1913 

 lAug. 10,1913 

 Aug. 25,1913 

 Sept. 15, 1913 

 Sept. 16, 1913 



Days, 

 i 

 i 

 5 

 4 

 4 

 4 

 4 

 3 



3* 

 4 

 4 

 4 



77.3 



79.5 



80.5 



82 



82 



80.9 



79.7 



88.6 



88 ' 



72.6 



81.9 



82.4 



1 Forenoon. 



