WHOLE VOL. APPLIED ENTOMOLOGY HOWARD 65 



evidence came in 1880 through work by Cook in Michigan, and 

 since that time arsenicals of one kind or another have become a nec- 

 essary orchard means of controUing the codHng moth ; and the gen- 

 eral use of this arsenical for leaf-eating insects of many kinds has 

 been recommended. 



For insects that suck the juices of plants, and therefore need not 

 a stomach poison but a contact poison, the first cheap, easily handled 

 and effective insecticide was discovered when Cook in Michigan in 

 1877 and 1878 found that kerosene would mix permanently with 

 soap solution and that this emulsion could be diluted. Kerosene oil 

 had been used as an insecticide before this, but it killed the foliage, 

 Hubbard independently made a kerosene-milk emulsion in 1881, and 

 later made a very satisfactory soap emulsion, the formula for which 

 remained standard for many years. 



Thus in the seventies and early eighties the two standard insecti- 

 cides were Paris green (or London purple, another arsenical) for 

 gnawing insects and kerosene-soap emulsion for sucking insects ; and 

 these, with Pyrethrum for household insects, remained for many 

 years the pieces dc resistance of the economic entomologist's stock 

 in trade in the way of insecticides. 



Along al)out this time the efficacy of the Bordeaux mixture was 

 discovered by French phytopathological exi:)erts, against mildew, and 

 its use soon became widespread for very many plant diseases. In 

 those days I was rather fond of chaffing Doctor Galloway and my 

 other friends in the Division of Phytopathology by saying that it was 

 an easy matter to handle their correspondence, because all they had 

 to do in reply to every letter received was to give the formula for the 

 Bordeaux nnxture. One day Doctor Galloway replied, *' If it were 

 not for Paris green and kerosene emulsion, it is difficult to see how 

 you entomologists could write a proper reply to a correspondent." 

 Mentally I had to admit our limitations, but of course I did not tell 

 Doctor Galloway so. 



It is not, however, my purpose to write a chapter on insecticides 

 nor in any way to indicate the progress that has been made since those 

 days. The publications of every experiment station in the United 

 States show all these later things. 



Journals or Periodicals on Economic Entomology 



The first journal to be devoted to applied entomology in the United 



States was The Practical Entomologist. In our account of Benjamin 



D. Walsh we have mentioned this journal at some length, but it is 



necessary to give it especial consideration under this heading. The 



