1915] © Ecological Foundations of Applied Entomology 9 
and not elsewhere. Still less do we know just why the bound- 
aries of its area of destruction fluctuate in its various outbreaks, 
or why the foci of its injuries shift from place to place in suc- 
cessive years. 
We know that such an outbreak or uprising is commonly 
preceded by widespread drouth for two or more years, and that 
as a rule its disappearance follows upon a season or more of 
comparatively wet weather, especially at its hatching time; 
but we do not know enough of other agencies contributing to 
either movement to give us means of either explanation or 
prevision; and of the climatic or meteorological agencies which 
seem to produce these effects, we do not know how or why they 
produce them, whether by some direct action upon the physio- 
logical or reproductive processes of the insects themselves, or 
indirectly through effects produced upon the food plants of the 
species, or upon its disease germs, or upon its newly discovered 
egg parasite, or upon several or all of these at once, -, together 
with other agencies as yet unknown. 
Concerning its single known effective insect parasite, 
discovered only last year, a species which seems to have special- 
ized upon the chinch-bug’s egg, we know that its rate of mul- 
tiplication so far surpasses that of its host that under favorable 
conditions it may rapidly overtake the latter and reduce an 
outbreak to insignificance—an apparently available weapon of 
first-class importance which has been made ready to our hands; 
but just what are the conditions favorable to its appearance, 
spread, and rapid increase, and whether these processes can be 
hastened artificially or not, of this we know nothing. We do 
not even know concerning this or any other parasitic insect 
how the parasite and the host are brought together in the 
field, whether because they have been so similarly tuned and 
timed to their environment that they find themselves brought 
into each other’s neighborhood automatically, because of like 
reactions to their surroundings, or by some more occult and less 
certain process. 
We know that at the beginning of a chinch-bug outbreak 
fungous disease seems to have little or no effect upon the 
rapidly multiplying hordes, but that when it is declining they 
sometimes burst forth like a flame in dry fuel. We have 
strongly suspected that this is due to a diminished average 
