368 MOSQmTOES of north AMERICA 



country from imported dried fiowerheads brought over in bulk. For this reason 

 it was, many years ago, deemed very desirable to establish a pyrethrum-growing 

 industry in the United States, and in 1881 the United States Entomological 

 Commission imported and distributed the seeds of the two species above men- 

 tioned to a number of correspondents in different parts of the country. The 

 total success was inconsiderable. Further experiments another year met with 

 comparative failure. About this time more extensive plantations were made in 

 California and an insect powder was made by the Buhach Producing and Manu- 

 facturing Company, of Stockton, California, which, being American grown and 

 freshly ground, came into use, and is still being produced and sold under the 

 proprietary name of " buhach," the word being supposedly derived from a Sla- 

 vonic word " buha," meaning flea. An article by the late D. W. Coquillett on 

 the production and manufacture of this powder will be found in Bulletin No. 12, 

 Division of Entomology, United States Department of Agriculture, 1886, pp. 

 7 to 16. 



Formerly most of the insect powders sold in the shops in this country had 

 pyrethrum powder as a basis. It is now difficult to get a pure and thoroughly 

 efficient powder. There is often adulteration. Frequently the powder made 

 from the dried flowerheads is adulterated with powder made from the stems, or 

 with other adulterants. Under the U. S. Insecticide Act of 1910 it is now re- 

 quired that the manufacturers of insect powders indicate on the label the com- 

 position of the powder, unless made of the flowerheads of the following three 

 species: 1. Chrysanthemum (Pyrethrum) dneraricefolium (Trev.) Bocc. ; 2. 

 (7. (P.) roseum Web. & Mohr. ; 3. Chrysanthemum marshallii Aschers (syn- 

 onym: Pyrethrum carneum M. B.). 



Pyrethrum powders are usually used dry and are puffed or blown into crevices 

 frequented by insects, or puffed or blown into the air of a room in which there 

 are mosquitoes or flies. The burning of the powder in a room at night is a 

 common practice. The powder is heaped up in a little pyramid which is lighted 

 at the top and burns slowly, giving off a dense and pungent smoke with an 

 odor very much like that of the Chinese punk used to light firecrackers. Often 

 the powder is moistened and moulded roughly into small cones, and after dry- 

 ing it burns readily and perhaps with less waste than does the dry powder. 

 Of late years in mosquito countries a number of mosquito pastilles have been 

 sold, and many of these are moulded from powders that contain more or less 

 pyrethrum. The efficacy of the burning pyrethrum in a close room is almost 

 perfect. It will not actually kill all the mosquitoes, but will stupefy them and 

 cause them to fall to the floor where they may be swept up and burned. With 

 the windows open, however, and constant currents of fresh air blowing through 

 the room, this fumigation is not especially effective, and it is necessary for pro- 

 tection to sit in the cloud of smoke. 



The pungent odor of burning pyrethrum is not disagreeable to most people, 

 but to some it is disagreeable, and with certain susceptible individuals it pro- 

 duces headache. It is apparently possible, however, to volatilize the oil without 

 producing the actual smoke. Mr. H. W. Henshaw informs us that a few years 



