176 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 11 
planned and supervised by the writer, the records being made by two 
assistants, Mr. George Acuff and Mr. F. G. Fisk. 
Poisoned Bait Experiments 
The testing of baits was done in alfalfa fields where the insects were 
fairly evenly distributed and at a time when practically all were in the 
adult stage. Six series of tests were made, beginning July 24 and end¬ 
ing August 6. The differential grasshopper (Melanoplus differentialis) 
predominated to the extent of at least 95 per cent. Altogether 3,276 
records were made including a total of 10,103 specimens. 
The baits to be tested were prepared at the laboratory, divided into 
two parts in each case for the first 97 experiments, and one lot for each 
experiment of the series was used by Mr. Acuff and the other lot by 
Mr. Fisk. To prevent drying out the materials were taken to the 
fields in paraffined paper sacks. In order to have an equal amount of 
surface of the various mixtures exposed to the air and for convenience 
in handling, the contents of the sacks were emptied into shallow tin 
pans, eight inches in diameter, marked with the same numbers as the 
sacks for identification, and distributed in rows with intervals of ten 
feet in localities where the grasshoppers were numerous and quite 
uniformly distributed. The two observers worked in different fields 
conducting the same tests simultaneously and their records were after¬ 
ward combined by the writer. 
Observations were made at intervals of fifteen minutes and a record 
was made in each case of the number of the insects found feeding or 
resting on the bait or within six inches of the pan in any direction. 
In passing along the row of pans for the purpose of making the observa¬ 
tions and of adding water from time to time in order to keep the baits 
in a moist condition, the hoppers were driven away from the baits to a 
greater or less extent. This was counteracted by the observer in each 
case, after completing the series of records, walking along the line of 
pans once on each side and about fifteen or twenty feet away. In 
some cases the entire row of pans was moved a few feet to one side or 
the other in accordance with the observers’ judgment as to the best 
means of securing the most uniform conditions throughout the period 
when the baits were exposed. 
It was found that the activity of the hoppers made it unusually diffi¬ 
cult to conduct field experiments on a small scale. From the first series 
of observations it was evident that a liberal allowance must be made for 
errors and variations and that no conclusions should be drawn except 
through the grouping of records or from observations repeated several 
times. As a general check, every other pan in one series (D) was used 
for the same bait combination, consisting of bran, canteloupe and water. 
