STRUCTURE, GROWTH AND ECONOMICS OF INSECTS 65 



examination, for it may sometimes happen that apparently trivial 

 and minor factors turn out to be important; for example, the discovery 

 of a preoviposition period for many Diptera furnishes a means of con- 

 trolling them at this vulnerable period. 



An important part of the equipment of the economic entomologist 

 is a knowledge of the principles of "ecology" which enables him to 

 analyze and scrutinize the various factors that play upon insects. The 

 ecological sciences that have a more or less direct bearing upon economic 

 entomology are Botany, Zoology, Chemistry, Physics, Geology and 

 Geography, and their outgrowths, Bacteriology, Forestry, Meteorology, 

 Physiology, and the group termed Agriculture. 



While a knowledge of these sciences is valuable in the study of in- 

 sect problems it must necessarily be general in its character and in- 

 sufficient for the solution of many of the more difficult problems. The 

 worker should, therefore, confer with speciaHsts in other depart- 

 ments. Especially is this necessary in deahng with measures of con- 

 trol. Sometimes recommendations are made which are at variance 

 with the most approved farm practice. By consultation with an 

 agronomist, horticulturist or forester such conflicting recommenda- 

 tion would not be given to the pubHc but would first be revised to 

 meet all requirements. 



In the study of insects of farm crops, for example, the investigator, 

 working along his own line, frequently reaches a position where he 

 cannot make further progress without more information from workers 

 in other branches and from experienced farmers. Such information 

 may relate to methods and action of fertilizers, methods of cultivation 

 and rotation, meteorological and physiographic influences, and the 

 practical application of measures of procedure. Similarly in dealing 

 with orchard insects progress in investigation can only be made when 

 there is full co-operation with the expert horticulturist, the orchardist, 

 the pathologist and others, who are able to give valuable advice and 

 assistance. 



As one might expect, every kind of insect demands its own par- 

 ticular method of investigation, for no two kinds of insects are oper- 

 ated upon by the same factors. Hence the successful investigator must 

 be able to contrive simple but effective devices for the determination of 

 the various factors. Costly insectaries and appliances are not abso- 

 lutely necessary; on the other hand, the tendency among the best work- 



