LONCHOCARPUS, DERRIS, AND PYRETHRUM CULTIVATION 2h 
cabbage worms, celery leaf tiers, potato leafhoppers, beet leafhoppers, . 
aphids, and tobacco flea beetles. During the recent war enormous 
quantities of pyrethrum were processed into aerosol sprays used to 
destroy anopheles mosquitoes in malarial regions where troops were 
concentrated. Aerosol sprays containing flower extracts, sometimes 
in combination with DDT, are now used as household insecticides. 
The effectiveness of pyrethrum sprays is considerably increased by 
blending with about 5 percent of sesame oil obtained from the seed of 
Sesamum indicum. For certain purposes, the pyrethrin content of 
sprays can be reduced as much as 40 percent without impairing their 
efficiency when sesame oil, which has no inherent insecticidal value, is 
used as a synergist. The effectiveness of pyrethrum sprays is also 
increased by the addition of certain synthetic synergists. The most 
important of these are piperony! cyclohexenone and piperony! butoxide 
29). 
C. cinerariaefolium, native to the Dalmatian coast of Yugoslavia, is 
a temperate-climate plant which is also successfully cultivated in cer- 
tain high-altitude regions of the ‘Tropics where the mean average 
temperature does not exceed 70° F. Although the crop has been grown 
experimentally in the United States and several north-European 
countries, it has not achieved commercial importance, because its 
excessive labor requirements and the comparatively low market value 
of the flowers make its culture unattractive in countries where wage 
scales are high. 
In the normal prewar year of 1938 world production of pyreth- 
rum reached 16,173 short tons (table 3). In the same year the 
United States imported 7,268 short tons or the equivalent of nearly 
45 percent of the total crop. Since the United States is by far the 
largest market for pyrethrum flowers, normally purchasing about halt 
the total world harvest, data (table 4) showing sources of supply from 
1933 through 1947 give a rather interesting indication of the way in 
which production of this crop hes increased, or declined, in various 
parts of the world during recent years. 
TasBLeE 3.—Pyrethrum production, by principal producing countries, 
1935-4 
Country 1935 | 1936 | 1937 | 1938 | 1939: | 19401 
| Short | Short | Short | Short | Short | Short 
| tons | tons | tons tons tons | tons 
ferian Congo.) |... +. 2 (2) (2) ?) | 24 | 110 
LET Se eS ee a* 250 250 250 300 | 300 600 
£2 a eee }12, 200 |13, 776 |12, 000 |12, 858 |11, 283 | 5, 167 
British East Africa (Kenya)__| 652 | 1,165 | 1,087 | 2,015 | 3,115] 5,472 
LEDS hak ee a | 697; 706); 702) 1,000 950} © 
Lin Se a oe 113, 799 |15, 897 |14, 039 |16, 173 |15, 672 | 11, 349 
1 Estimated. 
2 Not available. 
Compiled by Office of Foreign Agricultural Relations from U. 8S. Consular 
reports and other trade data. 
