4 BULLETIN 1066, U. S. DEPARTMENT OF AGRICULTURE. 



north attacks upon the fruit of the native butternut seem less exten- 

 sive, although at least a few infested nuts can usually be found upon 

 or beneath any bearing tree. A case of slight injury to the nuts was 

 found in 1920 in Jefferson County, N. Y. At nearly the same time 

 about 20 bearing butternut trees were examined along the St. Law- 

 rence River, in St. Lawrence County, N. Y., and not a trace of the in- 

 sect found. Beetles were reared from both shoots and fruit of -/. 

 sieboldiana collected at Lockport, N. Y., and larvae were abundant in 

 butternuts collected at Lake Winnepesaukee, in central New Hamp- 

 shire. 



Occasionally the larvae are found boring in young shoots of butter- 

 nut at French Creek, W. Va., oviposition evidently taking place in 

 the tips of these shoots before the fruit is large enough to be attacked. 

 On July 2, 1920, in the last-named locality, 60 half-grown butternuts 

 were picked at random from the lower branches of one tree. Of these 

 60 nuts 48 contained egg punctures of the curculio and 12 were 

 sound. A number of nearly full-grown larvae were also found bor- 

 ing in the terminal shoots and leaf petioles. These larva? averaged 

 larger than those in the nuts, indicating, as in numerous other obser- 

 vations made, that eggs are first laid in the shoots. 



LIFE HISTORY. 



The butternut curculio has but one generation annually, and, like 

 other members of the genus, passes the winter in the adult stage. In 

 West Virginia oviposition begins in May and continues practically 

 all summer, apparently reaching its maximum the last of June or the 

 first of July. 



EGG. 



The egg is oblong, oval, creamy white, with the surface like ground 

 glass. (PL I, D and E; PL II, A^ B, and C.) Three measured on 

 July 2, 1920, were uniformly 1 mm. long by 0.6 mm. wide. Two 

 measured on June 7, of the same year, were 0.9 mm. long by 0.6 mm. 

 wide. Britton and Kirk 5 give the following dimensions : Length, 

 0.95 mm. ; thickness, 0.57 mm. Most of the eggs hatch in from 8 to 

 10 days, although the period may extend to 15 days. 



The larvae are whitish, or dirty white, with brown head and black- 

 ish mandibles. (PL II, D ; PL III, A and B.) The length is 12 to 

 13 mm. and the thickness 3 mm. Feeding in the nuts and shoots, they 

 become full grown in four or five weeks and then enter the ground to 

 pupate. Nuts that are attacked when very small usually furnish 



5 Britton, W. E., and Kirk, H. B. Op. cit. 



