December, '14] WEBB: RICE WATER-WEEVIL 437 



low places. Most of the plants pulled up had roots severely pruned 

 by Lissorhoptrus. 



"Later in day found three or four Lissorhoptrus pupse in a field of 

 Japan rice about one and one-half miles south and a little west of 

 experiment station. Field had been drained for cutting. 



"Crowley, La., October 5, 1912: In same field (about one-fourth 

 mile east of experiment station) in which I found larvae and pupse of 

 L. simplex on September 27, I today washed out three living larvse 

 and one pupa of this species from Japan rice roots. Rice had been 

 cut at this place, but the ground is still wet in places. 



"Crowley, La., October 31, 1912: From rice roots pulled up yester- 

 day in stubblefield, I today washed out a living Lissorhoptrus larva 

 and one adult Lissorhoptrus." 



The above observations show the latest fall records of the immature 

 stages of this insect. Considering the period it takes for development 

 from egg to adult — five or six weeks — there would be ample time 

 during the spring, summer and fall for more than two generations. 

 However, it does not appear probable to the writer that there are more 

 than two generations per year. 



In the fall the adults of the last generation go into hibernation for 

 the winter in dead grass, as already described. The earliest date 

 in the fall, upon which adults have been found in hibernation in the 

 field by the writer, is September 30. 



Hosts Plants 



During the summer of 1912, the writer conducted a series of cage 

 tests to "determine in what native grasses the rice water-weevil would 

 breed. Different species of grass were transplanted to flat bottomed, 

 galvanized pans. The roots were well covered with dirt and the pans 

 then filled with water. They were kept filled with water above the 

 dirt during the tests. Two pans were used in each cage. Sometimes 

 only one kind of a grass was used in a pan, sometimes more than one. 

 After the water w^as placed in the pans adult rice water-weevils were 

 captured in rice fields and about one hundred weevils placed in each 

 pan. After allowing ample time for the weevils to lay eggs in the 

 roots of the different grasses, and for these eggs to produce larvae, the 

 roots of each kind of grass were washed out in water to determine 

 whether or not rice water-weevil larvae were present. The following 

 species of grasses were found to be infested by the rice water- weevil : 

 Echinochloa zelayensis H. B. K., Paspalum dissectum L., Paspaluni 

 boscianum Fliigge, Syntherisma sanguinalis (L) Dulac, Capriola dacty- 

 lon (L) Ktze, Axonopus compressus (Sw) Beauv., Panicum hiaus Ell, 



