Arizona AgricuIvTural Experiment Station 473 



varvino- fn)ni five ti) fifteen acres. Additional field tests will be 

 necessary before the new formulae can be recommended for use 

 against other species of grasshoppers in Arizona or against the 

 immature stages of the differential grasshopper. 



Miscellaneous observations made in connection with these ex- 

 ])eriments with poisoned baits concern the time of day when the 

 grasshoppers feed most actively, the distance grasshoppers travel 

 after eating a fatal dose of the bait and the amount of alfalfa which 

 adult differential grasshoppers consume per day. The observations 

 in regard to the time of day when the grasshoppers eat most ac- 

 tively were not conclusive, but from the records it appears that 

 there is no advantage in spreading the bait late in the afternoon or 

 very early in the morning, as has been generally supposed. Out 

 of 3382 observations made between 3 and 6:45 P. M. it was found 

 that 40.4 percent of the feeding records were between 3 and 3 :45, 

 30.3 percent between 4 and 4:45, 17.6 percent between 5 and 5:45 

 and 9.5 percent between 6 and 6:45. These observations will be 

 continued in order that the question in regard to the time of day 

 when the bait can best be scattered may be definitely determined. 

 In order to appreciate fully the effects of poisoned baits it is neces- 

 sar^■ to know how far the grasshoppers may travel after eating a 

 fatal dose of the poison. The observations made show that poisoned 

 grasshoppers very rarely traveled as far as 70 yards and that under 

 ordinary conditions few traveled further than 25 yards from the 

 place where a fatal dose of the poison is eaten. 



'^rhe observations made in regard to the amount of alfalfa 

 which grasshoppers may consume have been found to be very 

 effective in demonstration work. The figures obtained refer to 

 the differential grasshopper. It was found that one adult grass- 

 hopper per square yard may destroy the equivalent of three pounds 

 of alfalfa hay per acre per day. In a forty-acre field a moderate 

 infestation averaging 16 2-3 grasshoppers per square yard may 

 destroy the equivalent of one ton of alfalfa hay per day. Grass- 

 hopper infestations have frequently been noted averaging between 

 25 and 50 grasshoppers per square yard. It is obvious to a grower 

 to whom these calculations are presented that the expense of poi- 

 soning with one of the poisoned baits is exceedingly small in pro- 

 jwrtion to the damage done by the insects. 



A. W. MORRILI., 

 Consulting Bntomologist. 



