REMEDIAL MEASURES. 



65 



additional object of this experiment was to observe the readiness with 

 which beetles that had just emerged from the soil and had not had a 

 previous opportunity of feeding on unsprayed foliage would feed on 

 poisoned foliage as compared with beetles which were taken from 

 vineyards and which had fed to some extent upon unsprayed vines. 

 Accordingly 30 beetles, on emerging July 8, from soil inclosed with 

 wire screens, were placed on a sprayed plant in pot I. Thirty more 

 beetles collected in a vineyard, June 30, and fed on unsprayed leaves 

 until July 8, were placed (July 8) in pot II, also containing a sprayed 

 plant. At the same date 15 beetles which had just emerged were 

 placed on an unsprayed plant in pot III. 



Table XXIV show^s the death rate of the beetles in these three 

 cages. 



Table XXIV. — Experiments with poison sprays against grape root-worm beetles feeding 

 on vines in confinement at North East, Pa., in 1909. 



Pot I. Pot II. 



Pot III. 



30 beetles emerged 

 from soil July 8, 

 and at once re- 

 moved to 

 sprayed vine. 



30 beetles taken on 

 vines in the field 

 June 30 and 

 placed on 

 sprayed vine 

 July 8. 



15 beetles emerged 

 from soil July 8, 

 and removed at 

 once to un- 

 sprayed vine. 



Number 

 of dead 

 beetles. 



Date. 



Number 

 of dead 

 beetles. 



Date. 



Number 

 of dead 

 beetles. 



Date. 



16 

 12 

 2 



July 9 

 July 10 

 July 11 



3 



10 



13 



2 



1 



1 



July 9 

 July 10 

 July 11 

 July 12 

 July 13 

 July 17 





July 15 

 July 27 

 July 29 

 July 31 

 Aug. 14 

 Aug. 15 

 Aug. 28 



30 





30 





15 



Total. 







It was observed that the beetles just emerged from the soil and 

 which had been placed in pot I without having had an opportunity 

 to come in contact with unsprayed foliage fed as readily and indis- 

 criminately on the poisoned leaves as did those placed on the unsprayed 

 plant in pot III. The beetles placed on the other sprayed plant in 

 pot II, which had had 8 or 10 days of feeding on unsprayed leaves, 

 fed less upon the sprayed foliage, especially for the first 24 hours. A 

 glance at the table will show that 50 per cent of the beetles in pot I 

 died in 24 hours as against 10 per cent in pot II. On the fourth day 

 all beetles in pot I had died and also 85 per cent of those in pot II, 

 whereas it was not until the eighth day of the experiment that the 

 first dead beetle was found in pot III, and 73 per cent of the beetles 

 remained alive on this plant for more than a month. 



61282°— Bull. 89—10—5 



