IMPORTANT PECAN INSECTS AND THEIR CONTROL. 



19 



The pupa (fig. 21), to 

 wliich the full-grown larva 

 changes, is of the usual 

 form and without con- 

 spicuous m a r k i n g s . 

 When first formed it is 

 fairly dark brown, with a 

 tinge of oUve green, but 

 with age it turns to a deep 

 shiny mahogany brown. 

 The pupa is formed witliin 

 the larval case, and upon 

 the emergence of the moth 

 the pupal skin is not ex- 

 truded, as is the case with 

 some other moths. 



SEASONAL HISTORY AND HABITS. 



Only one generation of 

 the pecan leaf case-bearer 

 develops during the course 

 of a year, but more or less 

 variation exists in the de- 

 velopment of the different 

 stages, as will be shown 

 presently. For instance, 

 from material under ob- 

 servation during the sea- 

 son 1913 it was determined that the moths, nmnbering in all 269, 

 emerged between May 9 and July 12, inclusive. During 1914 the 

 dates of issuance for 385 moths varied from May 15 to August 5, 

 and during 1915 the dates at wliich the 591 moths emerged varied 

 from May 22 to July 23. For the three years the time of greatest, 

 or maximum, emergence was tlie same, being the latter half of June. 



Because of the wide varia- 

 tion in moth emergence a 

 corresponding variation oc- 

 curs also in the time of egg 

 laying. Eggs are deposited 

 always on the underside of 

 the leaves and usually near 

 the junction of the vein with 

 the midrib. (Fig. 22.) The 

 egg stage has been found to 

 last from 6 to 9 davs, the 



Fig. 19.— The pecan leaf case-bearer: Moth, or parent insect. , . ^ i ," j 



Enlarged. average being /.1 4 days. 



Fig. 18.— The pecan leaf case-bearer: Pecan tree defoliated. 



