June: '21) ford: grasshoppers and bran mash 281 



THE EFFECT OF POISON BRAN MASH ON GRASSHOPPERS 

 AND THE LAPSE OF TIME BETWEEN POISONING AND 



DEATH! 



By A. L. Ford, Scientific Assaiant, Bureau of Entomology, West Lafayette, Indiana 



The feeding powers of normal, healthy grasshoppers are well known 

 by practically every farmer. Also those who have used poison bran 

 mash for their control know that it is not an instantaneous killer, in 

 fact it usually takes one or two days for a hopper to die after feeding 

 on the poison. These two facts often tend to discourage the use of 

 poison mash for grasshopper control. Since a large army of hoppers 

 is capable of consuming vast amounts of green food in a single day, 

 many farmers say "Why poison when it will not kill for two days as 

 my crop will be taken in that length of time anyway." 



The wTiter has had to contend with this idea many times and yet 

 he had no positive data showing that the farmer was wrong. It was 

 with this in view that the author started to compile data showing that 

 although poisoned hoppers appear perfectly healthy until a short time 

 before death, they consume very little food after poisoning as com- 

 pared with unpoisoned hoppers during the same period of time. 



The work was done at the field laboratory of the Bureau of Ento- 

 mology at Lafayette, Indiana during the late summer and early fall 

 of 1919. A serious infestation of Melanoplus femur-rubrum occurred 

 in this locality at that time thus facilitating the work greatly. All 

 experiments were performed on adults of Melanoplus femur-rubrum. 



Adults of the above species were collected from the field by hand 

 s\^'eeping and placed in screen cages without food, where they were 

 left for one day in order to become sufficiently hungry to feed in cap- 

 tivity. A small amoimt of poison bran mash was then mixed and 

 placed in the cage. As the hoppers therein came to feed on it they 

 were timed in minutes. After feeding for the required time (two min- 

 utes) each hopper was removed and placed in an individual lantern 

 globe cage together with a piece of green com leaf cut to known dimen- 

 sions. This food was changed frequently until the hopper's death. 

 Each time the com leaf was removed the area eaten was traced on 

 cards, each hopper having an individual card. Later the total area 

 eaten by each hopper was determined in square inches of corn leaf by 

 means of the planimeter. In this way the amount each hopper ate 

 between the time of poisoning and death was accurately calculated. 

 Unpoisoned hoppers freshly swept from infested fields were run as 



