THE PEACH AND PLUM SLUG. 



99 



an oval cell somewhat less than one-fourth of an inch long in its 

 greatest diameter. If the cell be opened the larva will be seen to 

 have changed its form considerably. (See fig. 24, <?.) It is now like 

 a mummy of its former self. It is only about half its original size 

 when it entered the soil, has lost the power of locomotion, and is much 

 shriveled. This stage may be called the prepupa. Marlatt 1 terms 

 the corresponding stage of the pear slug the " contracted larva." 



In this form the insect remains for a period, depending on the 

 temperature, of from 5 to 7 days before pupation. Some individuals, 

 as in the case of the pear slug, which seem to be set aside to guard 

 against any catastrophe which might exterminate the species, remain 

 in this condition until long after their fellows have matured, before 

 finishing their life cycle. In one case a living prepupa was found 28 

 days after the latest adult reared from the same lot of larvse had 

 emerged. When the work was finished, on October 20, after cold 

 weather had set in, all of the cages were examined. In this examina- 

 I tion all of the living stages found were in the prepupal condition. 

 From this it appears that the species must hibernate in this form. 



THE PUPA. 



(Fig. 24,/) 



The pupal period varies in duration from 2 to 4 days, according to 

 the temperature. The data on the total quiescent period (i. e., pre- 

 pupa plus pupa) is shown in Table VII. 



Table VII. — Quiescent period of peach and plum slug, Tallulah, La. 



Lot No. 



110.. 

 112.. 

 114.. 

 1112. 

 1114. 

 1115. 



me. 



1117. 



1118. 

 1119. 

 1120. 



1121. 



1126. 



Total and average. 



Date of 

 fourth molt. 



Aug. 23... 

 Aug. 25... 



May 3 



May 22-29. 

 July 18. . . . 

 July 14-17. 



Aug. 12... 

 Aug. 14... 



Aug. 18... 

 Aug. 21... 

 Aug. 23-25 



Aug. 26-27 



Sept. 10-11.. 



Date of 

 emer- 

 gence. 



Sept. 1 

 Sept. 3 

 May 12 

 May 9 

 July 26 

 July 23 

 July 24 

 Aug. 19 

 Aug. 22 

 Aug. 23 

 Aug. 25 

 Sept. 16 

 Sept. 1 

 Sept. 3 

 ...do... 

 Sept. 4 

 Sept. 5 

 Sept. 20 

 Sept. 22 



Number 

 of indi- 

 viduals. 



34 



Quies- 

 cent 

 period. 



Days. 

 9.0 

 9.0 

 9.0 



13.5 

 8.0 

 7.5 

 8.5 

 7.0 

 8.0 

 9.0 

 7.0 

 2 26.0 

 8.0 



10.0 

 7.5 

 8.5 

 9.5 

 9.5 



11.5 



9.0 



i U. S. Dept. Agr., Div. Ent., Cir. 26, 2d ser., 1897. 



2 This individual held over till the next generation before emerging and is omitted from the average. 



