General Methods of Procedure 133 
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 Eutterflies 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, larve, pupe or eggs 
should be collected, cut open, and the eggs or larve 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. Ji 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 dillicult to readily secure an expert’s 
opinion. 
General Methods of Procedure. When it becomes neccs- 
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. 
