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POMONA COLLEGE JOURNAL OF ENTOMOLOGY 



realized how very great are the chances for uneven results for "shots" that 

 do not hit the mark. Contractors have not taken very kindly to the system 

 of marking tents, and estimating tree by tree after the tents were on. It 

 requires a lot more time and work. Formerly it was a common practice 

 for the estimator to prepare a schedule of the orchard and go through 

 it rapidly, marking, offhand, the dosages for all the trees, and thus one 

 man could serve several crews in this respect. Sometimes where the orchard 

 ran fairly uniform, the contractor would dismiss the whole matter in a 

 very easy way — by prescribing a uniform dosage for the whole orchard. 

 When we have become convinced that the guess-work system of esti- 

 mating is a most uncertain and costly one for the grower, and the Morrill 



Figure lOl. Even though these tents v/ere marked, anything liKe accurate estimating 



wrould be impossible 



or any other system of marking the tents is generally adopted, it will still 

 require great care and judgment to keep within bounds the possible margin 

 of error. We wish to show in this article that in careless hands there 

 are almost as great possibilities for error with the marked tents as without 

 them. Accuracy in tlie use of marked tents presupposes a tent of fairly 

 symmetrical form sloping the same on all sides, to be measured over the 

 top and around tlie base, well illu.strated in Figure 100. If the trees were 

 all absolutely symmetrical, and tlie top growth of the same density every- 

 where, this method would be child's play. But, unfortunatel}', tliis is rarely 

 the case. Our trees are usually unsymmetrical, and there is the utmost 

 variation in the density of the top growth. The density of the top growth 



