THE TERRAPIN SCALE. 



53 



fleshy lobes, between which are the sheaths of the copulatory appa- 

 ratus. (PL II, c.) The ventral eyes are represented at the end of 

 this instar by two brown spots. 



This instar is quite constant in its length, being almost invariably 

 2 days. Table XXXIII gives data upon 18 males from the rearing 



of June 24, 1913. 



The average length was 2 days. 



Table XXXIII. — Average duration of the prepupal instar for 18 specimens of the terrapin 



~j, Mont Alto, Pa., 1913. 



No. 



Date of 



second. 



molt. 



Date of 

 third 

 molt. 



Time in 

 prepupa. 



No. 



Date of 

 second 

 molt. 



Date of 

 third 

 molt. 



Time in 

 prepupa. 



1 



July 31 

 Aug. 4 

 July 31 

 July 30 

 ...do 



Aug. 2 

 Aug. 6 

 Aug. 2 

 Aug. 1 

 ...do..... 



...do 



Aug. 2 

 Aug. 1 

 Aug. 3 

 Aug. 2 



Days. 



2 

 2 

 2 

 2 

 2 

 2 

 2 

 2 

 2 

 2 



11 



July 31 

 July 30 

 July 31 

 July 29 

 Aug. 1 



...do 



Aug. 5 

 Aug. 4 



Aug. 3 

 Aug. 1 



...do 



July 31 

 Aug. 3 



...do 



Aug. 7 

 Aug. 6 



Days. 



3 



2 



12 



2 



3 



13 



1 



4 



14 



2 



5 



15 



2 



7*" 



...do 



...do 



...do 



Aug. 1 

 July 31 



16 



17 



2 

 2 



8... 



18 



2 



g 







10 



2 











Larvae that emerge upon the same day may vary as much as 10 

 days in the time required for them to reach the prepupa. The 

 normal time of entering this instar, however, is clearly denned for 

 most individuals. One-half of the males in any rearing will ordinarily 

 become prepupae upon the same date. The normal time for enter- 

 ing this instar in the region about Mont Alto, Pa., is upon the thirty- 

 eighth day after emerging from under the parent scale. 



Prepupae were abundant in the orchard at Mont Alto, Pa., in 1912, 

 from August 8 to August 20. They were present in largest numbers 

 about August 12; after this they became gradually less abundant 

 until August 25. After August 25 they were very scarce. At Mid- 

 vale, Pa., in 1913, the first prepupae were taken July 18. At Mont 

 Alto, Pa., in 1913, the first prepupse were taken July 24. This is 5 

 days earlier than they appeared at Mont Alto the preceding year. 



Since both sexes made the second molt at the same age, and 

 since the females migrate twigward upon the second day after this 

 molt, it happens that the twigward migration of the females coin- 

 cides with the prepupal instar of the male. In 1912 the first returned 

 females — 6 specimens in all — were taken July 29. While there were 

 undoubtedly as many prepupae as returned females at this time 

 upon the trees, none was found. By August 2 the number of returned 

 females had greatly increased and, upon this date, the first prepupae 

 of the season were taken. 



There was a difference in 1913 of 6 days in the appearance of 

 prepupae at the Wertz and in the Newcomer orchards. This was due 

 to the difference in the localities. The Wertz orchard has a strong 



