24 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



manager for a survey of the insect problems in the greenhouses of his 

 county, or a similar survey might be conducted among the vegetable 

 growers. 



In cooperating with the farm bureaus, it is important that there 

 should be a definite understanding as to the nature and extent of the 

 work. It is realized, however, that it is not always easy to plan demon- 

 stration work in insect control in advance of the season. The relative 

 importance of even our most common pests varies greatly from year to 

 year and it often happens that the greatest injury is done by an en- 

 tirely unexpected insect. In spite of this fact, demonstration work 

 should be planned as definitely as possible and adapted to the condi- 

 tions under which the crop is grown. In conducting demonstrations, 

 the aim should be to obtain as definite results as conditions will permit. 

 In field tests of the methods of insect control, untreated plats should 

 always be left for comparison. There are, however, some exceptions 

 to this rule as, for instance, in the case of the pear psylla where it is 

 necessary to treat the whole field to prevent reinfestation. Where 

 the value of the crop is great, it is usually necessary to have the un- 

 treated area small in extent. This is especially true in orchards of 

 large, old trees where few growers would care to lose the crop from more 

 than two or three trees. In determining the results of field tests of 

 methods of controlling insects, it is just as important to obtain definite 

 data as in the case of fertilizer tests. General impressions are of little 

 value. In some cases, as in the comparison of the effectiveness of 

 different insecticides in controlling fruit insects, this entails a large 

 amount of careful work — a tedious but necessary task, yet one well 

 worth while. Results backed by definite figures have much more 

 weight with those growers who are not able to see the tests personally 

 than those presented as based on personal opinion or vague observa- 

 tion. 



Since in many cases the control of insects must, in practice, be 

 connected with the control of plant diseases, it is desirable that demon- 

 strations be arranged whenever possible, in cooperation with the plant 

 pathologist of the college. 



In order to standardize spraying practice in a county, it is sometimes 

 desirable to publish an extension bulletin on the control of insects for 

 particular crops in that region. In such cases, the college representa- 

 tive would furnish the general discussion and illustrations, and the 

 farm bureau manager would be able to contribute those finer points of 

 control based on an intimate knowledge of local conditions that would 

 make the publication of greater practical value in his county. Ex- 

 perience has shown that a bulletin prepared for a particular region or 

 county is much more valuable to the growers than one written for the 



