Til \\\IAI. REPORTS OF DEPARTMENT OF AGRICULTURE, 1939 
found to be infested by the pea weevil. Five hundred and sev- 
enty eight graded crope were examined. This is approximately five 
g the average pea weevil Infestation in a comparable area during 
1937 and indicates that the L938 Infestation of the pea weevil was one 
of the ni"-! severe on record. The marked increase appears to be 
attributable principally to a mild preceding winter that allowed a 
high rate oi l] of adults and to a reduction of pea a* 
the Palouse area. This reduction apparently resulted in a higher 
degree oi concentration of the weevil population on the relatively 
small area of peas available for oviposition. 
I quiries addressed by this Bureau to entomologist s in New Jei 
New York, Indiana, Illinois, Michigan, and Wisconsin respecting the 
status of tlif pea weevil as a pesl In those States elicited tne Informa- 
tion that in New Jersey, Indiana. Illinois, and Wisconsin the insect 
is ordinarily present in very Limited numbers and cannot be consid- 
ered an important pest. In New York and in Michigan, however, 
the State authorities assert that, although the pea weevil is not now 
abundant, serious damage has been caused by this pest in those 
States during the past years when pea- were grown on a commercial 
scale by the dried pea industry for use as seed or feed. 
GLADIOLUS THRIPS 
Extensive tests made during L938 of various sprays to control the 
gladiolus thrips in the field and in the greenhouse led to a confirma- 
tion of the effectiveness of a tartar emetic-brown sugar spray for this 
purpose and its superiority to any other known insecticide. From 
these tests the following conclusions were reached: (1) Tartar emetic- 
brown sugar sprays, whether composed of 2, 3, or I pound- of tartar 
emetic and s or L6 pounds of brown sugar per 100 gallons of -pray. 
were of practically equal efficiency. On plots -prayed with 2 pounds 
of tartar emetic there appeared to be less residual effect of the tartar 
cinetie than where 4 pounds was used; hence the thrips caused more 
injury later in the flowering season on plots where the lower dilutions 
were used. No injury to gladiolus foliage resulted from the tartar 
emetic sprays, and the degree of control achieved was equal to thai ob- 
tained with -pray- containing paris green and brown sugar. (2 1 While 
a satisfactory degree of control was obtained with sprays containing 2 
pounds of pari- green and 64 pounds of brown sugar per LOO gallons 
of water, this spray caused moderate to severe foliage injury, the 
magnitude of which varied with the variety of gladiolus involved. 
(3) sprays containing derris and peanut oil not only failed to give a 
Satisfactory control of the gladiolus thrips, hut made the normal 
green surface of the foliage oily, and dust covered and yellowed it. 
The plant- sprayed with this combination were also stunted and 
retarded for more than ;i week in the development of their flower 
-pike-. The plant- treated with a derri- root powder spray contain- 
ing 0.02 percent of rotenone were more adversely affected by thrips 
and by the insecticide than those treated with a derris root -pray con 
taining 0.015 percent of rotenone, even though peanut oil was used at 
h concentration of l percent in both -pray-. ( \ ) A spray composed 
of derrh root powder containing 0.015 percent of rotenone, with var- 
nish a- :i sticker, phi- a sodium sulfate of technical lauryl alcohol as 
a wetting agent, gave only partial control of the thrips. (5) A -pray 
