INSECT POWDER 4e 
TasLe 51.—Insecticidal strength of finely-powdered parts of insect flowers 
Time . 
. Time 
nea Source cones | required 
paralyze to kill 
. : ; Minutes | Hours 
1 | Entire “open” flowers of C. cinerarizfolium____._.-.--.------------------- | 35 7 21 
EAMMERRESATN IC Lote orien ee eg Sy ee 2.4 1914 
Baie het yallowersirom sample diss Fee se Oe a ee We 1, 800 63 
Pa PTVCCOB AE OMnOM] SALLI G. ban sete a ee goles ee 90 50144 
aD OMICEC TOME GAINING Ere tn na ees noe ae ol ee = 240 80 
Disk flowers from ‘‘closed”’ flowers of C. cinerarizfolium____._____-__-_____- 8 314% 
TTS ere a ie ee ean er eas San ee SS a eae he Se eg OO ye ag pe ares eal Os 131 
SeeE LOWEESIOL CAROSCUAB ete eka SS) EE ECT aS ep ERS TET oe 7 23 
OREO MeCkemtr ey seberer rt ee Rr ete oy oP iti ie pce! ihe ese eae 23614 
Apparently the fruit and disk flowers of Chrysanthemum cinerar- 
rxfolium are the parts most active in paralyzing and killing roaches. 
These parts show the highest content of nitrogen, so that this element, 
although not actually a constituent of the active principle, appears to 
be present with it in a constant ratio, and hence can be used as a 
measure of the insecticidal activity. 
Summary of work on the actwe principle—All common organic 
solvents completely remove the insecticidal principle from the flowers 
of C. cinerariefolium. The insecticidal principle is not removed by 
a steam distillation. Water and dilute acids do not dissolve it, but 
dilute potassium hydroxid solution removes all of the activity from 
the powdered flowers. The active principle consists of two closely 
related complicated esters (pyrethrin I and pyrethrin IJ), present in 
the flowers to the extent of 0.2 to 0.3 per cent. The chemical nature 
of these two compounds is now well understood. Slight changes in 
their chemical structure greatly decrease their toxicity and in most 
cases destroy it completely. There seems to be little prospect of 
their commercial synthesis or of obtaining toxic compounds related 
to them but of less complicated structure. 
SUMMARY 
The fact that flowers of certain species of Pyrethrum have the 
property of killing various insects was known to the eastern Kuropeans 
more than a century ago. Since then this knowledge has gradually 
spread, until insect powder is now a common household convenience. 
This powder owes its insecticidal activity to a mixture of esters, the 
chemical nature of which is now well understood. These esters first 
benumb and then kill the insects brought into contact with the 
powder. Although generally considered to be harmless to the higher 
animals, it has produced symptoms of a more or less serious nature 
in a number of cases, according to the records in the literature. 
Insect flowers are now cultivated commercially in Dalmatia, Japan, 
Australia, France, Algeria, and California in the United States, the 
first two countries producing nearly all of the flowers that enter into 
international trade. The powder is made in each of these countries. 
In the enforcement of the insecticide act, insect powder has been 
found adulterated in a variety of ways. In some instances such sub- 
stances as lead chromate, curcuma, and yellow ocher are added to give 
color. Other species of flowers, like the Hungarian or ox-eye daisy, 
are substituted in whole or in part for the true insect flower. Almond 
