8 BULLETIN 1303, U. S. DEPARTMENT OF AGRICULTURE 



LARVA STAGE 



EMERGENCE OF LARV.E FROM HIBERNATION 



The overwintering larvae become active and leave their winter 

 cases (hibernacula) during the latter part of March or the first part 

 of April, at which time the buds on pecan trees begin to open. After 

 feeding slightly upon the unfolding buds, these spring-brood larvae 

 migrate to the rapidly growing succulent shoots, in which they feed 

 by tunneling out the interior, keeping the burrows open by casting 

 out the frass pellets from the hole where the initial attack was made 

 (PL IV). It has been determined from field observations that the 

 larvae usually begin to attack the pecan shoots during the second 

 week in April, and after feeding in this manner for two weeks or more 

 the larvae transform to pupae within their burrows. During 1916 

 the spring-brood larvae that were under observation pupated from 

 April 24 to May 12, and in 1917 from April 19 to May 1. Records 

 show, however, that a few larvae can be found on pecan trees, espe- 

 cially the Stuart variety, as late as the second week in May. 



FIRST-BROOD LARVAE 



The length of larval life for the first brood ranges from 22 to 29 

 days, the average being about 26 days. The maximum hatching of 

 first-brood larvae occurs during the third week in May, but the period 

 of hatching is quite extended. 



SECOND-BROOD LARV.E 



The majority of the second-brood eggs hatch during the last week 

 in June and the first 10 days of July, but the hatching for all eggs of 

 this brood extends over a long period. The average length of the 

 larva stage for the second brood was found to be 25.27 days. 



THIRD-BROOD LARVAE 



The hatching of third-brood larvae begins about the middle of 

 August and continues until the first part of September. The latest 

 hatching of third-brood larvae in rearing cages occurred on September 

 3, but under natural conditions it is likely that larvae hatch over a 

 longer period. The third-brood larvae feed very sparingly for three 

 or four weeks and then go into hibernation by constructing hiber- 

 nacula, which are attached to the buds. Although the larvae feed for 

 several weeks, they do not attain a size greater than one-tenth of an 

 inch. In rearing work it has been observed that the larvae are very 

 prone to construct their hibernacula prematurely when the food 



Elant in breeding cages is not kept in the best of condition. The 

 irvae remain in their hibernacula throughout the winter, and with 

 the advent of spring they become active just as the buds on the pecan 

 trees are unfolding. 



PUPA STAGE 



PLACE OF PUPATION OF THE OVERWINTERING LARV^J 



The spring-brood pupae are formed within the shoots in which the 

 larvae complete their growth. Near the mouth of its burrow the full- 

 grown larva prepares out of particles of frass and excrement a flimsy 

 silken-lined cell or cocoon, where its transformation to the pupa stage 

 occurs (PI. IV). 



