632 THE SMALL GRAINS 



crown and taken entirely away from the field. If cut 

 at the soil surface they will grow again, and produce seed 

 as often as cut, several times during a season. If the 

 weed is allowed to seed in any quantity the first year of 

 appearance, it will afterward be almost impossible to 

 eradicate it. Complete eradication will be greatly aided 

 by crop rotation, including a cultivated crop. Con- 

 certed community action is necessary to effect per- 

 manent eradication (Chambliss and Adams, 1915, pp. 

 16-18). 



711. Rice water weevil (Lissorhoptrw simplex, Say). - 

 The most injurious insect enemy of growing rice in the 

 southern states is the rice water weevil. In its larval 

 stage the insect is known to rice-growers as the " rice 

 root maggot." The larvae feed on the roots of rice 

 plants, while the adults cause some injury by feeding on 

 rice leaves. The insect breeds only where there is water, 

 and feeds on plants growing in wet places. The eggs are 

 laid on roots in water or on weeds, where the larvae are 

 hatched and transform into pupae, and finally into adult 

 insects. One generation in a season appears to be the 

 rule, but two generations may sometimes be produced. 

 The adults hibernate in the winter and invade the rice 

 fields in the spring. 



As the insect lives only in water, it is recommended as 

 a means of control to drain the rice fields, causing them 

 to dry sufficiently to exterminate the insect at the proper 

 time before the larvae have greatly weakened the plants. 

 Alternate flooding and drying, if done properly, is effec- 

 tive. Very shallow flooding checks infestation, while 

 fertilizers aid the plants to overcome injury. 



712. Other rice insects are occasionally injurious. The 

 rice grub is the larva of a large scarabaeid beetle (Chalepus 



