61 



c 



all badly infested plants before the issuance of the first new brood of 

 moths. From current reports during the year it would seem that the 

 proper time to begin this work is about the 

 middle of July, as the larvae are then nearly 

 mature and the moths appear soon afterwards. 



THE COMMON RHUBARB CTJRCTJLIO. 



(Lixus concavus Say.) 



Residents of the Eastern States who are 

 familiar with the appearance of growing rhu- 

 barb or pieplant [Rheum rhaponticwn) can 

 not fail to have noticed that stalks here and 

 there are often injured, so that the juice ex- 

 udes and, drying, forms clear tear-like drops.. 

 Closer examination will show that these drops 

 exude from holes gnawed by an insect, and if 

 one should seek the culprit he will not be long 

 in tracing the cause to a large rusty -coated, 

 long-snouted beetle known as Lixus concavus 

 Say, and which we may call the common rhu- 

 barb curculio to distinguish it from another 

 closely related species, L. mucidus, which has 

 similar habits. 



May 9, 1899, the great numbers of beetles 

 of Lixus concavus in a plat of rhubarb at Ten- 

 nallytown, D. 0. , attracted the writer's atten- 

 tion and led to further study of its life econ- 

 omy and the preparation of the present paper. 

 Almost every stalk of rhubarb had been 

 attacked and some so badly as to interfere 

 with their sale, at least to many would-be pur- 

 chasers. One of these stalks served as the 

 model of the illustration here presented as 

 figure 14. 



According to the published statement of 

 Mr. F. M. Webster (Proc. Ent, Soc. Wash., 

 Vol. II, p. 339), the insect treated by Dr. CM. 

 Weed in publications of the Ohio Agricul- 

 tural Experiment Station (Bui. No. 6, Vol. II, 

 p. 153, and Bui. No. 8, Vol. Ill, 2d series, pp. 

 232-235) under this name is not the true con- 

 cavus, but mucidus. The investigations which have been conducted 

 during the year, however, indicate that this is a matter of scientific 



!i; 



ji 



Fig. 14.— Stalk of rhubarb injured 

 by Lixus concavus — reduced one- 

 fourth (original). 



