66 



Lixus and Sphenophorus, these genera being- of about the same aver- 

 age size, but not at all likely to be mistaken by anyone who studies the 

 subject of entomology. 



FOOD PLANTS. 



As already shown, this species does not develop in rhubarb. The 

 only larval food plant observed by Mr. Webster in central Illinois 

 and Indiana was wild sunflower, Uelianthus grosseserratus, a common 

 Western plant. In and about the District of Columbia, as well as in 

 the vicinity of New York City and Ithaca, N. Y., this curculio was 

 observed only on rhubarb and dock, and the latter is the favorite and 

 apparently the only larval food plant about Washington. It is prob- 

 able that all species of Koimex having suitable stems for the develop- 

 ment of the larva are utilized for this purpose. The species from 

 which the beetles have been reared are curled dock (Rumex crispus) 

 and broad -leaved or bitter dock (R. ohtusifolia). 



Lixus concavus is the only species observed on Rumex or rhubarb in 

 this vicinity. 



The adult of this curculio feeds upon the foliage of all of the plants 

 mentioned, usually by gnawing the edges of the leaves, but it seems 

 probable that a considerable quantity of nourishment is also taken 

 when the stems are punctured for oviposition, if indeed they are not 

 often punctured, as seems most likely, for food alone. 



THE INSECT'S LIFE HISTORY. 



Hibernation and time of appearance.— This rhubarb curculio hiber- 

 nates as a beetle in and near the District of Columbia, and is one of 

 our early arrivals, appearing in the field some time in April, presuma- 

 bly with the appearance of its food plant, or about the time that the 

 stems are large enough for oviposition. Pairing and egg deposit 

 begin soon afterwards. 



From the scarcity of beetles in the field after the dying out of the 

 hibernating generation in the summer, the writer had formed the 

 opinion that beetles overwintered in the stalks, and particularly 

 because Mr. Webster had found that hibernation also took place in 

 other stages (larva and pupa) in the localities where he had made obser- 

 vations. It was therefore surprising that in spite of several attempts, 

 made at intervals between the second week of September to the second 

 week of October to find beetles, none could be found in stems in which 

 there was evidence that they had developed. 



A beetle that issued August 12 was kept for upwards of two months 

 without food. October 18 a beetle was captured in the field that had 

 evidently been flying, and this, together with the beetle reared in con- 

 finement, were placed in a jar with dock leaves October 18. The latter 



