2 BULLETIN 1066, 17. S. DEPARTMENT OF AGRICULTURE. 
THE BUTTERNUT CURCULIO. 1 
The butternut curculio has been known commonly in the past 
either as the " walnut weevil " or " walnut curculio." It would seem 
that for the members of this group whose larvae feed in immature 
nuts the term " curculio " is to be preferred in order to disassociate 
them in the popular mind from members of the Balaninus group, 
which have long been known as "nut weevils." The other part of the 
name is here restricted to " butternut " for the reason that this species 
appears to confine its attacks almost exclusively to our native butter- 
nut (Juglans cinerea) and to introduced walnuts of the butternut 
type. There is a very similar but distinct species to which the name 
" walnut curculio " could be applied with equal appropriateness. In 
rearing several hundred specimens the writer has failed to obtain 
a single individual of C . juglandis from infested young black wal- 
nuts {Juglans nigra) , the species commonly attacking black walnuts 
being C onotracJielus retentus Say, described on pages 7-11. One 
beetle of C. retentus was found among a lot of beetles of C. juglandis 
reared from butternuts, and it is possible that with both species of 
insect there is occasional interchange of hosts. 
The butternut curculio also attacks and injures seriously the fruit 
and small branches of various species of introduced walnuts, being 
especially destructive to the Japanese walnuts (-7. sieboldiana and 
/. cordiformis) which are of the butternut type. (PI. II, D ; PI. 
Ill, B.) 
DISTRIBUTION. 
The known range of the butternut curculio extends from the 
Provinces of Ontario and Quebec, Canada, south through the Xew 
England States, Wisconsin, Iowa, and Kansas to Alabama and 
Georgia. Britton and Kirk 2 record it from 20 States within the 
boundary just given. The distribution of the insect follows rather 
closely the natural range of the butternut, which is its favorite native 
food plant. Throughout the general range of the insect there are 
evidently many localities, even where host trees abound, in which it 
is very rarely found. In many other localities it is abundant and 
destructive. 
FOOD PLANTS. 
Britton and Kirk 2 give the food plants in the order of preference 
shown as follows : Juglans cordiformis, J. sieboldiana, J. cinerea, J. 
regia, J. nigra, and*/, mandshuria. They quote Dr. Kobert T. Mor- 
i C onotrachelus juglandis Lee.; suborder Rhynchophora, family Curculionidao, tribe 
Cryptorhynchini. 
3 Britton, W. E., and Kirk, II. B. Life history and habits of the walnut weevil 
or curculio. In 12th Ann. Rept. State Ent. Conn., p. 240-253. 1912. 
