NATIONAL COUNCIL OF HORTICULTURE 23 



sects, it is nevertheless necessary for man to supplement their work 

 by the use of insecticidal substances. The applied science of economic 

 entomology had its foundation in this necessity. 



It would be of interest, did time permit, to briefly outline the 

 development of economic entomology in America, as constituting a 

 most interesting chapter in the history of our phenomenal agricultural 

 growth. Insect problems of national importance have, one after another, 

 presented themselves for solution, and a knowledge of methods of 

 insect control has become more and more necessary in agricultural 

 and horticultural operations. At the present time in the United States 

 and Canada, some 150 persons are devoting their time, in whole or in 

 part, to the scientific study of injurious insects, and this number would 

 perhaps be doubled, if account be taken of those engaged in the 

 enforcement of crop-pest laws. Some $300,000 are annually spent in 

 work pertaining to destructive insects, not including emergency appro- 

 priations by the Federal Government, as for the cotton boll weevil, the 

 gypsy moth, the eradication of the cattle tick, etc. 



Neglecting, however, this phase of the subject, attention will be 

 called to some of the methods, and their efficiency, at present employed 

 in reducing insect injuries. 



Broadly speaking, our present battery for insect warfare is about 

 as follows : 



(1) Various poisons, as Paris green, ar.senate of lead, hellebore, 

 etc., for biting insects, which are sprayed or dusted on their 

 food plants. 



(2) Various caustic, soapy and penetrating sprays, as lime sulphur 



wash, whale oil soap, kerosene and crude petroleum emul- 

 sions, etc. These are more especially for sucking insects, 

 and destroy them by corroding or penetrating their bodies, 

 or by stopping up their breathing pores. 



(3) Poisonous gases, so used as to poison the air breathed by 

 insects, as hydrocyanic acid gas, carbon bisulphide, and sul- 

 phur dioxide. 



(4) The utilization of parasitic and predaceous insects, and para- 



sitic fungous and bacterial diseases. 



(5) Cultural methods, as timely planting, cultivation, fertilization, 

 fall plowing, rotation, pruning, etc. 



(6) The employment of plants or parts of plants more or less 



resistant to insect attack, as for grafting stock. 



(7) Mechanical methods, as worming for borers, jarring for cur- 

 culio, etc. 



(8) Legislation, to prevent the introduction and dissemination of 

 noxious species. 



Spraying. The first two mentioned classes of insecticides, namely 

 food poisons and contact remedies, are used mostly as sprays, and 

 spraying without doubt is our most effective way of controlling insects. 

 It is especially valuable for the orchardist, and for the grower of small 

 fruits and truck crops. Of field crops, potatoes, tobacco and cotton are 



