INSECTS INJURIOUS TO MISCELLANEOUS CROPS 365 



larvae are abundant. The larvae become full grown in about 

 three weeks in summer, when they descend to the soil and pupate 

 in small silken cells on or just below the surface. The moths 

 emerge about eight days later, so that in midsummer the com- 

 plete life cycle occupies about a month. In Texas there are 

 probably five generations a year, and in Nebraska and Illinois 

 three or four generations. 



Control. The plowing of infested land in late fall or winter, 

 or thorough disking of alfalfa will be found largely to control the 

 pest. Where it appears on cultivated crops it may be readily 

 destroyed by at once spraying or dusting with arsenate of lead. 

 The destruction of the weeds upon which it feeds is obviously 

 important in preventing the undue multiplication of the pest. 



The Rhubarb Curculio * 



Rhubarb is but little troubled with insect pests, but occa- 

 sionally the stalks are found with numerous punctures from 



FIG. 308. The rhubarb curculio (Lixus concavus Say): a, beetle; b, egg; 

 c, newly hatched larva; d, full grown larva; e, pupa;/, back view of last 

 abdominal segment of pupa all about twice natural size. (After Chit- 

 tenden, U. S. Dept. Agr.) 



which the juice exudes. This has been caused by the feeding 

 and oviposition of a large rusty-brown snout-beetle, which is 

 usually found on the affected plants. It is about three-quarters 



* Lixus concavus Say. Family Curculionidw. See F. H. Chittenden, 

 Bulletin 23, n. s., Division of Entomology, p. 61. 



