47 
THE RELATION OF METEOROLOGICAL CONDITIONS TO 
INSECT DEVELOPMENT. 
That meteorological conditions have a strong bearing on the in¬ 
crease and decrease of the number of insects, is a fact well known 
not only to scientists, but to every careful observer. Every farmer 
is well aware of the fact that insects are more abundant in warm 
dry weather, than in cold wet seasons. As a general rule the in¬ 
crease in insect life is more marked in unusually warm and dry 
years, than in those of the opposite character. The years of great¬ 
est drought are those in which insects have been most abundant 
and injurious, especially when those years have been accompanied, 
as is usually the case, by more than ordinary heat. 
Even those dry years, during which the temperature has fallen 
below the average, have generally been marked by an increase in 
insect life, or their influence in this direction has appeared in the 
following season. 
As the lack of sufficient moisture in such seasons weakens the 
plants and renders them less able to withstand the attacks of their 
insect foes, the injury is proportionally greater than it would other¬ 
wise be. 
Although a knowledge of this fact is important in the study of 
insect life, it is too general to be of much practical value, unless 
meteorologists could predict, with greater certainty than at present 
appears to be possible, the character of the coming year. 
It is important, therefore, to examine into, and if possible point 
out more particularly this relation; in other words, to ascertain if 
possible how far this increase in insect development is due to a 
lack of moisture, and how far to increased temperature, to what 
extent it is affected by the character of the winter, and also that 
of the summer months, the injurious species that increase most 
rapidly under the favorable climatic conditions, and those whose 
numbers appear to be least affected by the changes. 
It is possible that when this subject has been more thoroughly 
studied, the entomologist may be able to fix upon the particular 
month, or limited portion of the year, whose character determines 
the status of particular species the following season. 
It is already known that some of the most notedly injurious 
species require two consecutive favorable seasons for their develop¬ 
ment in the great numbers sometimes seen. This is especially true 
