10 THE RICE WATER-WEEVIL. 



With the aim of working out. the details of development of the 

 larval and pupal stages, a number of larvae were placed on the roots 

 of young rice plants, each of which was set in water within a glass 

 tube, the tubes being simply stood in a holder. Attempts to carry 

 through the development of pupae from larva: when subjected to con- 

 stant exposure to light proved only partially successful, but better 

 progress, although still lacking completeness, was made after shield- 

 ing the tubes from light and supplying a small amount of earth with 

 the roots and water. 



SEASONAL HISTORY AND GENERATIONS. 



Adults as well as partially and full grown larva 1 , and also without 

 doubt the pupa 1 , occur in many fields up to the time of draining for 

 harvest. With late crops in the coast region, however, and in the 

 fields of Arkansas on account of the difference of the season in that 

 State, the number of weevils in all these stages diminishes about the 

 time when the plants begin to head in the latter part of August. 

 Weevils found in fields after the drawing off of water to permit 

 harvesting are apt to be freshly emerged individuals of a new gen- 

 eration. From a collection of infested roots obtained by Mr. Pierce 

 at Beaumont, Tex., June 28, 1004. adults emerged as early as July 2 

 following. In case such early emerged weevils breed at once, they 

 have a chance to produce a second generation in a season, provided 

 they find late flooded fields or suitable water holes. At Stuttgart, 

 Ark., on September 12, Mr. Hood found roots of rice infested by a 

 few larva? which he regarded as representatives of a second genera- 

 tion. The last larva found by the writer during his stay at Crow- 

 ley, La., was taken September 25. While the weevils that emerge in 

 July possibly lay eggs for a second generation, the species is prin- 

 cipally propagated in one yearly generation. 



In the spring, before many of the rice fields were flooded, Mr. Hood 

 collected adults on grasses and red rice growing in ditches and other 

 places containing water. Since the weevils have not been known to 

 breed in such places until the soil and water become sufficiently warm, 

 at which time the flooding of rice fields is well under way, the deduc- 

 tion is made that low temperatures up to this time exert a restrictive 

 influence upon breeding. 



Examination of roots of red rice and other plants growing in a 

 constantly flooded ditch at Crowley. La., on October 3, failed to dis- 

 close any evidences of infestation at the time. These results show 

 conclusively that the weevil does not breed at this time of year even 

 in most favorable situations. Xot only were the adults absent, but 

 the lack of feeding scars on the leaves denoted that they had not 

 visited there for some time. 



