24 
LIFE HISTORY. 
Of all insects the codling moth has the largest number of ])iog- 
raphers. It has been studied in nearly every country in the world 
and in all climates in which it exists. The early accounts were always 
more or less vague and inexact and gave rise to many false ideas. 
Gradually these points were worked out until to-day we can say that 
the life history of the insect is as well if not better known than that 
of any other. Yet, with all the knowledge we have of it, there remain 
several important points to be determined by future work. 
It is a fundamental principle of economic entomology that in order 
to successfully combat an insect the life histor}^ of that insect must be 
given a keen, searching stud3\ With few exceptions these studies 
reveal some point in the life of the insect at which it is vulnerable 
to preventive or remedial measures. Without this knowledge efforts 
are wasted and in some cases are a positive aid to the insects. It can 
not be too strongly urged that each fruit grower make himself familiar 
with the life histor}^ of the codling moth from personal observation, 
for by doing so he is placed in a position to understand the reasons for 
measures of control and to exercise his ingenuity in applying the same 
to his own orchard. 
The ease with which collections can be made in the larval stage and 
the accessibility of literature pertaining to it should specially com- 
mend this insect to teachers as a subject for nature-stud}^ lessons. 
In the present studies upon this insect particular care has been taken 
to keep the different stages under observation in exactly the same con- 
ditions of temperature, moisture, and light as were present in the 
orchard in which the cages were located, and as a result the writer is 
able to present some definite data in regard to the effect of temperature 
upon the length of the stages of the insect under normal conditions. 
As in other lepidopterous insects, the life of the codling moth is 
divided into four distinct stages — egg, larva, pupa, and adult. In the 
winter and early spring the larvae ma}' be found in their cocoons in 
various places, as in cracks and holes in the trees. Later the larva 
transforms into a pupa, and this in turn changes to a moth, which in 
turn lays eggs. 
THE EGG. 
Since the time of Roesel many authors have mentioned the egg of 
the codling moth and stated where it was laid, l)ut it was as late as 
1893 that it was first accurately described and figured. In 1874 Mr. 
W. H. Hurl but described the egg as being about one-eighth of an inch 
in length and nearly white. Riley described it as being very small 
and of a yellow color. Messrs. A. J. Cook, Koebele, Weir, and others 
undoubtedly saw the eggs, but Cook in 1881 and Miss M. Walton 
doubtless saw the eggs of some other insect. 
