70 \X\r.\l. REPORTS OF DEPARTMENT OF AGRICULTURE, 1939 
control prior to migration but did not protect the bolls from attack. 
At both localities undiluted calcium arsenate dust gave better control 
than the diluted dusts, and mopping with sweetened poison was 
again entirely inadequate for protection against the weevils. 
SOIL ivn RY PROM CALCIUM ARSENATE AND CRYOLITE 
The 1938 yield of cotton on the plot at Tallulah which received 
MX) pound- ol* calcium arsenate per acre from L931 to L935, or a total 
of 2,000 pounds, was less than that on the untreated check, probably 
owing to the reduced growth in 1937 of Austrian Winter peas and 
hairy vetch planted for green-manure crops. During the winter 
of l ( .»:;s_;;«.t Austrian Winter peas, vetch, and oat- planted as winter 
cover crop- produced as much on the treated ;i- on the untn 
plots for the first time since the experiment was begun. It appears 
that the injurious effects of arsenic on the -oil disappeared after 4 
years. On the plots representative of the -even major soil types of 
Mississippi, previously reported, the effects of arsenic added in April 
193.") seem to he disappearing a.- a result of fixation or leaching of the 
arsenic, and the yields from crops susceptible to arsenical injury are 
increasing. Preliminary te>ts with cryolite on 1 i i_ri it sandy soils • 
cially susceptible to arsenical injury indicate that application- up to 
2,000 pounds per acre had no deleterious effect on the germination or 
growth of cowpeas and oats. 
COTTON FLEA HOPPER 
There was a very heavy infestation of the cotton ilea hopper in 
southern Texas, and the gains from dusting experiment- in 1938 were 
the highest ever obtained. The average gam from dusting with 
several insecticides on thirty-six 1-acre plots was 311 pounds 
cotton (63 percent) over the cheeks, and the net profit was s ( .».74 per 
acre. The maximum jrain of 680 pounds and a profit of s-2.">.ll per 
acre followed dusting with a mixture of 1 part of calcium arsenate 
and '2 parts of sulfur, and showed that this mixture i- superior to 
other proportions of calcium arsenate and sulfur and to sulfur alone. 
This mixture is now being used extensively by growers, the applica- 
tions being made from airplanes and ground dusting machines. Very 
finely divided or "micronized" sulfur dusted at the rate of 7 pounds 
per acre was as effective as 15 pounds of ordinary 325-mesh dusting 
sulfur. Mixtures of sulfur and barium fluosilicate or cryolite were 
not effective against the flea hopper. 
HEMIPTEROUS INSECTS 
The hemipterous insects continue to he the most important insect 
enemies of cotton in Arizona. Among the more important species 
are the pentatomids Euschistus impietwentris Stal, Cnlorochroa 9ayi 
Stal, and Thyanta mutator (F.) and the mirids Lygtu 
Knight, A. pratensis oblineatus (Say). /.. elisus Van P., and Oreonti- 
ades femoralis Van D. The Last species was more abundant on cotton 
in L938 than in previous year-. The pentatomid- \'cv(\ on the larger 
bolls, causing malformation and staining of the lint by the introduc- 
tion of pathogenic organisms, A survey of the cotton in the State 
Showed that 81.5 percent of the bolls of short-Staple and 1 L6 percent 
of those of long-staple cotton had been punctured. The mirids injure 
