June, '12] HOLLISTER: TOBACCO EXTRACTS 263 



tents of Sonora, Sinaloa and the Gulf Coast of Lower California 

 should hold such an insect, if not several of them. Large extents of 

 that region are almost rainless and possess a very low average of atmos- 

 pheric humidity. Coccids abound there and there certainly should 

 their enemies abound as well. Parasites and coccineHids adapted 

 to the driest and hottest parts of that region should be able to con- 

 tinue active through the hot dry season of the Peruvian coast region. 

 Lower California, known as a land of drought and desert, offers 

 the most promise of all in this respect in its Gulf coast region near the 

 middle of the peninsula. This part receives the least rainfall of the 

 whole region above outlined, has the least atmospheric humidity, and 

 is evidently the hottest throughout the year. It is probable that an 

 effort will be made to investigate this region in the hope of securing 

 the requisite agency for use against Hemichionaspis minor in Peru. 



TOBACCO EXTRACTS, THEIR COMPARATIVE VALUES AS 



INSECTICIDES 



B}' W. O. HoLLiSTER, Research Laboratory, Parke, Davis & Co., Detroit, Mich. 



The use of tobacco as an insecticide is recommended in the earliest 

 available literature on the subject. It, therefore, bears the unique 

 distinction of being not only one of the oldest of insecticides, but one 

 most frequently used at the present time for a certain class of insects. 

 Just when it was first used is not known, although several of the early 

 writers refer to it in their papers on remedies for insects. 



The first available report of its use was in 1763 when it was recom- 

 mended in France as a remedy for plant lice. Both tobacco water 

 and tobacco powder were used at that time. The first mention of its 

 use in America was in 1814 by Yates of Albany, who applied tobacco 

 water for sucking insects. WilHam Corbett in the English Gardener, 

 1829, recommended tobacco juice for woolly aphis and Thomas Fessen- 

 den in the New American Gardener, 1832, included tobacco in a list 

 of materials Avhich he stated ''may annoy or completely destroy in- 

 sects." 



Doctor Riley in 1884, said that the three most valuable insecticides 

 of general application in use during the earh^ daj^s of economic ento- 

 mology, and up to within a few j^ears, were tobacco, white hellebore 

 and soap. 



It is very evident that tobacco is an old time remedy and its use at 

 the present daj^ for the eradication of a certain class of insects is indis- 

 pensable. During the early use of tobacco it was employed for all 

 sorts of insects, one writer only a short time ago reported that a decoc- 



