THE EICE WATER-WEEVIL. 15 



lasted six days, and calculating on a bcsis of five stalks to a stool the 

 infestation was reduced from 40 to 7.2 ppr cent. The writer's own 

 examination of this rice on August 1, the second day of reflooding, 

 gave substantial evidence of the reduction of larvae in corresponding 

 numbers, the count resulting in 3 larvae on the roots of 40 stalks. 



At Pine Bluff, Ark., on August 5 the writer made examinations 

 in a rice field that had been drained for five days. ( )n the roots of 

 105 stalks only nine larvae were found alive. The infestation there- 

 fore amounted to approximately 9 per cent. The owner stated that 

 before draining two and three larva 1 occurred on a stool. Calculating 

 five stalks per stool, the infestation then could not have been less than 

 33^ per cent. In some places the ground was still saturated, but most 

 of it was stiff mud. That the draining really caused a reduction in 

 the number of larvae by death was evidenced by the finding of two 

 dead ones, and some of the live ones seemed weak as if about ready to 

 die. Xot many roots were badly cut and the draining began at an op- 

 portune time. The pumping of water on» this field was resumed 

 August 8, but it was not wholly flooded until a few days later. The 

 drying covered seven days at least. No rain fell during this time, 

 and the ground had begun to crack from drying. The results were 

 considered very beneficial, as the larvae caused no further trouble and 

 the rice headed out splendidly. 



EFFECTS OF RUNNING WATER. 



Direct observations, as well as the testimony of growers, have 

 brought out the fact that rice growing in running water suffers little 

 from weevil attacks. In these cases, however, no considerable area 

 has yet been seen in which the water flowed with any perceptible cur- 

 rent. To maintain a distinct moving flood over a large field would 

 require an immense supply of water. The instances that have been 

 observed were confined to spots or small plats covered by the inflow 

 of water from a canal or ditch. In spreading onto a field from an 

 inlet the current soon loses force and any low temperature. Where 

 a cool flow of water is pumped from a well directly onto a field the 

 low temperature seems to exert a controlling factor against infesta- 

 tion. But these cases are rare, because the rice demands warm tem- 

 peratures for vigorous growth, and the sun heat greatly restricts the 

 cool area. 



EFFECTS OF DEEP AND SHALLOW FLOODING AND STAGNATION. 



Deep water and stagnant water greatly favor development of 

 weevils. As already pointed out, rice in spots or areas of deep flood- 

 ing is most severely attacked. Severity of attacks is especially 



