General Methods of Procedure 133 



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The necessity of measures against insects can in many 

 cases be ascertained by timely observation and trial collec- 

 tions, as mentioned on the previous page, when the relative 

 number of butterflies in the summer, or of cocoons, egg 

 masses or wintering caterpillars in the fall, indicate the prob- 

 ability of next year's expectations. Next, an investigation 

 of the health conditions of caterpillars and cocoons is indi- 

 cated, for if at least fifty per cent, are found diseased, no 

 measures need be taken. Signs of disease are sluggishness 

 in feeding or other unusual behavior of caterpillars, although 

 this will be possible for only an expert to judge. To make 

 sure, fifty to a hundred caterpillars, larvas, pupas or eggs 

 should be collected, cut open, and the eggs or larvas of 

 parasites found, or else they may be hatched under proper 

 conditions. These investigations require some skill and 

 entomological knowledge and are, therefore, best made by an 

 expert. Next, the observation of weather conditions per- 

 mits a judgment as to the likelihood of ordinary or extraordi- 

 nary development. If the winter has been very severe, 

 or else open and wet, or if early or late frosts are likely to 

 have damaged the wintering caterpillars, there may be no 

 necessity for making warfare. 



To be sure, these prognostications require knowledge and 

 judgment, but with an official entomologist in almost every 

 state, it should not be difiicult to readily secure an expert's 

 opinion. 



General Methods of Procedure. When it becomes neces- 

 sary to fight a pest, there are four general methods to choose 

 from: namely, searching for and killing the insect directly in 

 any of its phases of development, egg, cocoon, larva, or imago; 

 preventing it from reaching its feeding or breeding place by 

 placing impediments in the way, when it can be collected and 

 destroyed; trapping or baiting it; or lastly, poisoning its food. 



