INSECT POWDER 7, 
before the flowers are opened fully, the crop is comparatively small, but if har- 
vested after full bloom, the strength of the powder for killing insects is lessened. 
Care should be taken to select the time of harvesting. The proper time is when 
the flower petals are fully opened, until their ends are on a level with the top of 
the calyx and the pollen is falling. Old men and women, carrying hand baskets, 
ean easily pick the flowers by holding them between the middle and fore fingers, 
and by pressing down at the top of the flower with the thumb. By shaking up 
and down, the flowers are soon separated from the stem. A woman generally 
can pick the flowers at the rate of about 40 to 50 pounds during the day. 
In some districts a simpler method of harvesting is adopted. At the time of full 
bloom, the flowers, together with their leaves and stems, are reaped about twice, 
with a tool like a short-handled rake with comb-shaped teeth, and dried in the sun. 
It should be added that powder made from flowers picked by this comb-toothed 
instrument is either inferior or no good, for the reason that flowers in all stages of 
blooming are thereby picked, whereas to obtain the full strength flowers must be 
picked at exactly the right stage of blooming which can be done only by hand. 
The flowers picked are spread on straw mats and dried in a sunny place, ex- 
posed to the wind. Then they are moved to a drying room, which should have a 
good draft. Shelves, similar to those used in sericulture, are made by laying down 
rush screens or old newspapers on the top, where the fiowers are arranged thinly 
and turned over twice or more a day. A few days later, when dried to a certain 
extent, they may be spread out thicker than at first. The drying is finished in 6 or 
7 days. When there is no drying room, they are dried entirely in the sun. By 
adopting this system, a much greater quantity can be dried in a shorter time, 
although it is inferior in quality compared with that dried in the shade. Drying 
in the sun takes only three days in fine weather. If the drying takes too long, the 
flowers lose their strength. Drying has reached the proper stage when the flowers 
ean be roughly powdered by breaking them into small pieces upon rubbing with 
the thumb and forefinger. Artificial heat is also applied at large factories, the 
standard of the heat being 150° F. 
In addition to the districts named by West, the provinces of Ki-i 
and Mikawa are mentioned by Fujitani (89) as supplying flowers. 
Herrera (129) states that the C. cinerarizxfolium grows well in Mexico. 
Efforts to introduce the cultivation of Pyrethrum into this country 
were made by the United States Department of Agriculture as early 
as 1859. In that year Bishop (30) reported that 250 plants of Pyre- 
thrum caucasicum were in the course of cultivation in the Experimental 
and Propagating Garden at Washington, D. C. Markoe (188) de- 
scribes the growing of P. roseum by Asa Gray in the Cambridge, Mass., 
Botanical Garden from seeds distributed by the Government in 1859. 
The seeds yielded by the American-grown plants were sown but did 
not germinate. The root stocks of the’old plants, however, threw u 
shoots in the second year. Gray was of the opinion that the cul- 
tivation of the plant could be made profitable in this country. In 
1860 Abel (1) stated that he was informed by persons receiving some 
of this seed that the plants were in a flourishing condition. In the 
_ eighties the United States Department of Agriculture renewed its 
efforts to establish the cultivation of insect-powder-producing plants. 
In Washington, D. C., Riley (222) obtained good results. He dis- 
tributed seed to correspondents in Alabama, California, Dakota, 
Georgia, Illinois, Indiana, lowa, Kansas, Kentucky, Maryland, Michi- 
gan, Mississippi, Missouri, New Hampshire, New Jersey, New York, 
North Carolina, Ohio, Ontario, Pennsylvania, Vermont, and Virginia, 
but in all the States, except California, the results were unfavorable, 
due, apparently, largely to drought and bad seed. 
On the other hand, better results were obtained by persons more 
familiar with growing plants. Thus Peter Henderson wrote Riley 
(222) regarding P. rosewm: ‘I have grown the plant and its varieties 
for 10 years. It is of the easiest cultivation, either by seeds or 
divisions. It now ramifies into a great variety of all shades, from 
