II ANNUAL REPORTS 01 DEPARTMENT OF AGRICULTURE, 1049 
Effect <>n Plants of N arioiifl 1)1)1 Formulations I sed t« » Control 
\\ bite-fringed Beetle! 
Field tests were made to determine the effect on various plant 
DDT foliage sprays applied for the control of white-fringed beetles. 
No injury to any of the plants, which included sweetpotatoes, pea- 
nuts, cotton, crowder peas, squash, soybeans, corn, and sorghum, was 
detected from DDT emulsion applied at 2 pounds of DDT per 
When sweetpotatoes, cotton, crowder peas, and soybeans were evalu- 
ated as to yield, no significant difference was round between any 
t reated crop and its checE plot. 
From .July through November L948, 17 ornamental nurs 
Alahaina. Mississippi, and Louisiana were visited periodically t 
cord any plain injury resulting from the treatment of the soil with 50 
pounds of technical DDT per acre in L947 or L948, and in 11 of these 
nurseries any injury to foliage from applications at the rate of one- 
naif pound of technical 1)1 >T per acre made at 2-week intervals 
throughout June, July, and August L948. Observations were made 
on 706,555 ornamental plant- representing m genera, L31 sp< 
an undetermined number of varieties. These plants included L5i 
azalea plants representing 6 species and }'.» varieties, and 263,966 
camellia plant- of 2 species and 3 17 variet ies. No injury to any plant 
from the use of DDT was observed. Some complaints were made by 
growers that a plant had been injured. In each case, however, obvious 
factors, such as inadequate drainage, improper care, unsatisfactory 
soil conditions, sunscald, shade, diseases, and insect pests, were estab- 
lished as causing the condition of which the nurseryman complained, 
DDT foliage sprays have been used regularly for the control of 
white-fringed bettles since I^H'k In L948, 25,000 acres were treated 
with emulsion or suspension sprays at a rate equivalent to ] ■_» to 1 
pound of technical DDT per acre. No garden, truck, or foliage plants 
included in the spray schedule; however, no injury from spraying 
to cover crops to be turned under or to nat ive vegetal ion was obsen ecL 
CHEMICAL STUDIES OF INSECTICIDES 
New Insecticides Similar to V\ rethrum Made Sj nthetically 
Chemicals almost identical with the natural insecticidal principles 
m pyrethrum flowers have been synthesized in the laboratory. This 
achievement Is the culmination of about L5 years' investigations on 
the chemistry of pyrethrum by chemists of this Bureau. The com- 
pounds responsible for the insecticidal properties of pyrethrum are 
esters known as pyrethrins. The uewrj synthesized compounds are 
closely related to one of these esters. They have the same b 
down, or paralyzing, effect on insects, and indications are that they 
will not lose i hen insect killing value so quickly as the natural mate- 
rial. ( me of t hese compounds, or \>\ rethroids, has been found in Labo- 
ratory tests to be several time* as toxic to house flies as the combined 
active principles of pyrethrum flowers. The toxicity of the synthetic 
products to higher animals is being investigated. 
