EVOLUTION OF THE COLOR PATTERN IN THE MICROLEPI- 

 DOPTEROUS GENUS LITHOCOLLETIS. 



By Annette Frances Braun. 



CONTENTS. 



I. Introduction 105 



II. Methods and Observations 106 



(a) Systematic Position and Characteristics of Lithocolletis 106 



(6) Color Classes Represented and Structure of Scales 109 



(c) Comparative Study of the Adult Markings 110 



{d) Ontogenetic Development of the Color Pattern 118 



1. Historical 118 



2. Methods 121 



3. Observations 123 



4. Discussion and Conclusions 141 



(e) Phylogenetic Development of the Color Pattern 149 



III. General Discussion 160 



IV. Summary ^ 164 



I. INTRODUCTION. 



The interest in a study of the origin of the many and complex forms of color 

 pattern in insects hes mainly in the hope that such a study may give additional 

 insight into the fundamental principles of evolution in general. With few 

 exceptions, such as the work of Tower on Leptinotarsa, researches of this nature 

 have been confined to the Macrolepidoptera, chiefly to the butterflies and higher 

 moths. The Microlepidoptera, which are less advanced from the viewpoint 

 of evolution, have been almost neglected. Yet, within this group, several of 

 the older and larger genera afford excehent and ample material for such an 

 investigation. To secure convincing data, a critical study, both ontogenetic 

 and phylogenetic, must be made of the species of a large genus, in which the 

 color patterns, while sufficiently diverse to indicate that a considerable degree 

 of evolution has taken place, are still comparatively simple. 



The genus Lithocolletis fulfills to an extraordinary extent these require- 

 ments; hence the following investigations were undertaken with the object of 

 ascertaining the modes of origin of the various color patterns in this genus and 

 the influences which have been operative in their evolution. The study of 

 adult color patterns has extended over a period of several years; the observa- 

 tions on pupal development were made during the summer of 1910. 



It is a pleasure to express to Prof. M. F. Guyer my appreciation of his 

 many helpful suggestions during the progress of my work. 



