NATURAL CONTROL. 131 



occurred, however, early in January, at which time all weevils which 

 had survived the starvation of the fall were deeply hidden in hiber- 

 nation shelters, where sudden changes of temperature have little 

 effect. 



The survival from hibernation at Tallulah, La., was only one-half 

 of 1 per cent, as shown in the hibernation statistics, and this, no 

 doubt, must be attributed to the rare combination of early freeze, 

 subsequent long duration of effective temperatures without food, and 

 finally a period of minimum fatal temperatures. 



One of the most interesting features of the fall of 1910 in Texas was 

 the presence of two small areas in which the first freeze was delayed 

 from one to two months. (Fig. 27.) We call attention to the most 

 interesting of these cases. The freeze of October 29 was felt in all 

 Texas above the latitude of 31°, except in Erath, part of Comanche, 

 part of Brown, Eastland, Callahan, Taylor, Jones, and Haskell Coun- 

 ties in central-west Texas. In this frost-free area in the following 

 October, 1911, a very heavy infestation was found at Cisco, in East- 

 land County, and at Brownwood, in Brown County. The infestation 

 diminished in every direction from those places. At Lampasas, 60 

 miles southeast of Brownwood, where we would naturally expect a 

 much higher infestation than at Cisco, very slight damage occurred, 

 and at Granbury, in Hood County, 60 miles east of Cisco, where the 

 weevils have been present since 1904, they were extremely difficult 

 to find. Thus, it is seen that a territory which had had the weevil 

 much longer than either Brownwood or Cisco had fewer weevils in 

 1911, because it experienced an earlier killing frost. 



EFFECTS OF FLOODING UPON THE WEEVIL. 



Tests at Victoria, Tex., in 1904, were divided into two parts, each 

 of which included both the immature and mature stages. In each 

 part floating and submergence were tested. In the tests made upon 

 the floating power of adults, weevils 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 sufficient to float weevils which were placed upon it carefully. 

 The generally hairy condition of the surface of the weevil's body 

 prevents it from being readily wetted, so that it may struggle for 

 some time in the water without becoming really wet. YvTien 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. 



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 

 only slightly moist on the inside. These contained six larvae and 

 four 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 three normal adults ; one pupa died, and one square was found 



