February, '13] NEWELL: RICE water weevil 59 



culty in taking full-sized eggs from females secured in the act of mating 

 and dissected on the spot. 



Larva. The larvse of the rice water-weevil are familiarly known to 

 the planters as ''rice maggots" and but few are familiar with the 

 adult stage of the insect. 



The larvse eat off the small, tender roots and rootlets and injure the 

 larger, older roots by gnawing into them, or even by eating out a 

 cavity within the root amply large enough to contain the larva itself. 

 Where the root is merely gnawed and not entered, a scar is left which 

 is quite characteristic and which remains visible, probably, until the 

 root dies and decays. 



The larvse are found most abundant where the individual rice i)lants 

 are smaller and of a yellowish cast, instead of a bright, dark green. 

 When as many as 4 to 8 larvae (or sometimes 10 to 12) are found on 

 the roots of each plant, the latter will be found to have a yellowish, 

 sickly look, with some of the lower leaves discolored and dead. Plants 

 which have their roots heavily infested come up, when pulled, very 

 easily, in marked contrast to the difficulty experienced in trying to 

 pull up healthy, non-infested plants. 



Infested plants are constantly trying to overcome the injury by 

 putting out new rootlets, but as long as the infestation remains heavy 

 these rootlets are in turn destroyed. It is by means of these rootlets 

 that the plants "recover" from the attack, in the language of the rice 

 growers. The plant proper does not really recuperate, however, until 

 the majority of the larvse have reached maturity and their injury to 

 the rootlets comes to an end. Even in the case of marked "recovery" 

 there can be no doubt but what the productive capacity of the individ- 

 ual plant is severely curtailed. 



Duration of Generations. As all my efforts to get the weevils 

 to oviposit in captivity were futile, I could only approximate the dura- 

 tion of larval life by deduction from field conditions. 



At the time adult weevils were so abundant in small Japan rice at 

 Lake Arthur on June 3, I examined a field of older Japan rice adjacent. 

 While the adult weevils were very abundant in the small rice, just 

 flooded, they were extremely scarce in the older Japan. A long exam- 

 ination brought to light three partially grown larvse on the roots of 

 the older Japan, these larvse being possibly referable to L. simplex. 

 A field of early-planted Honduras rice, also near at hand, showed no 

 adult weevils and no root infestation. The roots of both the large 

 Japan and the large Honduras lacked, absolutely, the characteristic 

 feeding scars which are left by the water-weevil larvse . From these 

 conditions it appeared that the weevils in the younger Japan rice were 

 the ones which would deposit eggs for the first generation on rice. 



