139 



unharmad. Weevils were working normall}^ upon the plants. No 

 diminution in their numbers could be seen and it was apparent that 

 the overflow caused no check either to the development of the imma- 

 ture stages or to the activity of the adults. These observations 

 emphasize the fact that the weevil can not be drowned out. 



LABORATORY OBSERYATIONS UPON TIME WEEVILS WILL FLOAT OR 

 ENDURE SUBMERGENCE. 



These tests were divided into two parts, each of which includes 

 both the immature and mature stages. In each part floating and sub- 

 mergence were tested. 



Sixty squares believed from external examination to be infested 

 were floated in a driving rain for six hours. They were then removed 

 and left for several days, during which time 75 per cent of them pro- 

 duced normal adults. Ten squares which were floated in driving rain 

 for six hours were opened at once, and in every case found to be but 

 slightly wet upon the inside. These contained 6 larvae and 4 pupse, 

 and all were in perfect condition. 



As squares float normally, submergence tests were considered 

 extreme. Five squares were submerged fOr six hours, and after that 

 produced 3 normal adults; 1 pupa died, and 1 square was found to 

 have been iiuinfested. Five more squares were submerged for thirty- 

 one hours. These produced 2 normal adults, and 1 pupa died in the 

 process of molting after removal from the square. Death was prob- 

 ably caused in the last case b}^ dr3ang; 1 square was found to contain 

 a dead pupa, and 1 was not infested. To test the possibility of its 

 living, should the square be penetrated by water, a naked pupa was 

 submerged for six hours, but in spite of this unusual treatment it pro- 

 duced a normal adult. Numerous larvae removed from squares and 

 placed in water pupated in one or two days, and several pupae remained 

 alive though floating for several days in water before they transformed 

 into adults. 



In the tests made upon the floating power of adults, v/eevils were 

 isolated and placed in water in tumblers. They were dropped from a 

 considerable distance above the surface, so that they became entirely 

 submerged, and they rose to the surface naturally. The surface 

 tension of the water was found to be sufl^icient to float weevils which 

 were placed upon it carefulty. The generally hairy condition of the 

 surface of the weevil's body prevents its being readih^ wetted, so that 

 it may struggle for some time in the water without becoming really 

 wet. When dropped, as described above, weevils float head downward, 

 with the tip of the abdomen above the surface. In the submergence 

 tests weevils were held down by a wire screen, and all bubbles were 

 removed from their bodies by a pipette, thus making the tests as 

 severe as possible. 



