ON THE LIFE-HISTORY OF THE APPLE 

 FRUIT-MINER, ARGVRESTHIA CONJUGELLA ZELL. 



By 

 Hanjiro Okamoto. 



Entomologist, Hokkaido Agricultural Experiment Station, Sapporo, Japan. 



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It is a fundamental principle of economic entomology that in order to suc- 

 cessfully combat an insect the life history of that iiisect must be given a keen, 

 searching study. With 'icw 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 insect. 



In the present studies upon the apple fruit-miner a particular care has been 

 taken to keep the different stages of the insect during the experiment in exactly 

 the same conditions as to temperature, moisture and light as in the orchard in 

 which the cages were located. 



As in other lepidopterous insects, the life of the apple fruit-miner could be 

 divided into four distinct stages — egg, larva, pupa atid adult. In winter and early 

 spring, the larva may be found in theii cocoons in the soil. Later the larva trans- 

 forms into a pupa, and this in turn changes to a moth, which in turn lays eggs. 



The Egg. 



The egg is flat and oval in shape. It varies in size from 0.38 to 0.48 mm. in 

 length and from 0.25 to 0.3 mm. in breadth. The surface is covered with a net- 

 work of ridges which are much closer together toward the central portion than 

 around the edge. The color varies with the age of the embryo. When the egg 

 is first laid, it is of a white color, sometimes with a decided yellowish thinge, later 

 becoming light yellowish. 



[Trans, of Sapporo Natural History Soc. Vol. VI. Part, 3. Jan. igiy.l 



