THE PECAN NUT CASE-BEARER 11 
The data on the length of the pupal period of the first-brood 
pupae for 1915 are incomplete, but in the case of the few indi- 
viduals under observation the pupal period lasted from 10 to 11 days. 
NUMBER OF GENERATIONS 
Life-history studies have shown that under normal conditions the 
pecan nut case-bearer has three generations annually, at Monticello, 
Fla., and that it passes the winter in the immature larva stage of the 
third generation. These third-brood larvae after feeding sparingly 
for a few weeks migrate during the latter part of September or the 
first part of October to the buds, where they construct small, com- 
pactly woven hibernacula, in which they hibernate until the following 
spring, when the buds on pecan trees are beginning to open. In con- 
finement it may be possible for the pecan nut case-bearer to have four 
generations. 
PARASITIC ENEMIES 
The writer has on several occasions reared a number of parasitic 
insects from the larvae and pupae of the pecan nut case-bearer as 
follows: Exorista (Nemorilla) pyste Walk., 3 Hdbrobracon variabilis 
Cush., 4 CalliepMaltes grapholitJiae Cress., 4 Cremastus (Zaleptopygus) 
sp., 5 and Angitia sp. 4 The most effective parasite is the tachinid fly 
Exorista pyste Walk., which was reared in large numbers from the 
larvae and pupae, and is no doubt a very important factor in the 
natural control of this pest. The braconid Habrobracon variabilis 
also was frequently bred, and is perhaps second in importance among 
the parasites of the pecan nut case-bearer. 
CONTROL MEASURES 
Investigations so far conducted show that the best method of 
control against the pecan nut case-bearer is spraying with arsenate 
of lead. 6 The arsenate should be used at the rate of 1 pound of the 
powdered form, or 2 pounds of the paste form, to each 50 gallons of 
water, to which should be added the milk of lime from 3 pounds of 
slaked lime. The addition of lime is necessary to prevent arsenical 
injury to the foliage and nuts. Three applications will be required 
and should be at the following periods : 
1. Soon after the nuts have set, at which time they are about the 
size of garden peas. 
2. One week or 10 days later. 
3. From four to five weeks after the second application. 
The date for the first application at Monticello, Fla., during the 
season of 1915 was found to be May 15, and in 1916 it was May 12. 
The time of spraying, however, will vary somewhat according to 
latitude and the character of the season. The first and second appli- 
cations are the most important in the control of the pecan nut case- 
bearer, as most of the damage to the nuts is usually caused by the 
larvae of the first generation. Since only a small portion of the nut 
crop is attacked by the second-brood larva?, it is suggested that if 
growers desire to reduce spraying of their orchards to a minimum 
3 Determined by W. R. Walton. 
4 Determined by R. A. Cushman. 
8 Determined by R. A. Cushman. The genus Cremastus now embraces the old genus Zaleptopygus. 
6 In connection with life-history investigations, spraying experiments were conducted during 1915 and 
1916, the results of which were reported in detail in Farmers' Bulletin 843 of the United States Department 
of Agriculture, pages 6 to 9. Further spraying experiments were begun in the spring of 1917, but could not 
be successfully carried out on account of the mildness of the infestation of the insect in the orchard 
selected for this work. 
