BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 45 
indicated consistently that there has occurred a gradual decline in 
adult grasshopper populations in practically all the areas under ob- 
servation during the period 1936-38. This decline, however, has not 
been reflected in general grasshopper conditions throughout the Great 
Plains States. The intensive studies have also shown that the great- 
est grasshopper populations were recorded during the years of mini- 
mum rainfall and that when precipitation reached normal amounts 
populations declined to a point where slight damage was to be ex- 
pected. It was also demonstrated that general damage from grass- 
hopper attack does not become apparent until there are present five 
or more hoppers per square yard. 
A publication containing the applicable results of recent investi- 
gations of grasshopper control, Farmers' Bulletin 1828, was issued in 
June. It contains much new material on grasshopper control, in- 
cluding four optional formulas for the preparation of bait having as 
bases mill-run bran, mixed feed, or shorts; standard wheat bran; 
low-grade flour; or sawdust with molasses. Liquid sodium arsenite 
was the poisoning agent. 
In extensive experiments with substitutes for wheat bran or saw- 
dust in grasshopper baits, cottonseed hulls, citrus meal, and chopped 
alfalfa have given promising results. Chopped-alfalfa baits showed 
a tendency to form lumps and therefore cannot be recommended for 
general use until some way is found to overcome this tendency. The 
large-scale use of bran and saw T dust substitutes also depends on their 
cost and availability in large quantities as compared with bran and 
sawdust. 
The late summer of 1938 was marked by unprecedented flights of 
lesser migratory grasshoppers from western South Dakota into 
western North Dakota and eastern Montana, where they laid enor- 
mous numbers of eggs. In June 1939, contrary to all previous ex- 
perience, it developed that most of these grasshoppers had deposited 
their eggs not only on cultivated and recently reverted lands but also 
on open range lands where countless millions of young hoppers ap- 
peared. Only the most rapid and vigorous action on the part of 
those in charge of grasshopper control, by the enlistment of a fleet 
of airplanes to distribute grasshopper bait, prevented a major dis- 
aster to crops. It was feared that great flights of hoppers would 
originate on these heavily infested areas to reinfest neighboring areas 
which had already been freed from hoppers by the distribution of 
poisoned bait. Fortunately, however, such flights as did occur were 
mostly to the northwestward, and no great damage to crops occurred 
from this source. 
THE MORMON CRICKET 
The standard method of control for Mormon crickets for many 
years has been to dust them with a mixture of sodium arsenite and 
lime or diatomaceous earth. This method is effective but laborious 
and, owing to the arsenical content of the dust and the class of labor 
necessarily employed in distributing it, involves considerable danger 
to livestock where carelessness in distribution occurs. Because of 
these defects, since 1935 efforts have been made to develop a poisoned 
bait that would be efficient for Mormon cricket control. Such a bail 
containing sodium fluosilicate as the poisoning agent was developed 
in 1938. but opportunity for testing it on a large scale did not occur 
