THE CODLING MOTH 
By B. A. Porter 
Bureau of Entomology and Plant Quarantine, Agricultural Research 
Administration, United States Depariment of Agriculture 
(With 6 plates) 
INTRODUCTION 
The codling moth, Carpocapsa pomonella L., is a conspicuous exam- 
ple of an insect species that has been able to maintain itself as a 
destructive pest of apple orchards for more than a hundred years in 
spite of the continuous development and improvement of control 
practices. Forty or more investigators employed by the United States 
Department of Agriculture, State agricultural experiment stations 
and other State agencies, and insecticide companies, are now devoting 
all or a considerable part of their time to this problem, and progress 
is constantly being made in the development of control measures. The 
literature has become so voluminous that no one person has ever re- 
viewed all of it. Yet with all of this progress the insect continues to 
cause serious losses to apple growers. Since similar trends have been 
exhibited by certain other insects, a review of the evolution of control 
measures for the codling moth, and the conditions that have permitted 
the insect species to maintain itself in spite of these control measures, 
may be of interest to students of insect control problems. 
BIOLOGY OF THE CODLING MOTH 
For the benefit of readers who are not well acquainted with the 
codling moth, a brief summary of its seasonal history will be given: 
The codling moth passes the winter as full-grown larvae in cocoons, 
in crevices in the bark of the tree, under loose flakes of bark, in debris 
on the ground, and in similar places (pl. 1, fig. 1). In early spring, 
as the buds begin to push out, the insect changes to the pupa (pl. 1, 
fig. 1), or stage in which the transformation from larva to adult moth 
takes place (pl. 1, fig. 2). The first moths appear about the time the 
apple trees come into bloom; and shortly begin to lay their white, 
scalelike eggs (pl. 2, fig. 1) on the leaves, chiefly around a fruit spur. 
Later many of the eggs are placed directly on the fruit. The newly 
347 
