A CONTRIBUTION TO THE PHYSIOLOGY OF WING 

 DEVELOPMENT IN APHIDS. 1 



GEORGE O. SHINJI. 

 UNIVERSITY OF MISSOURI, COLUMBIA, Mo. 



CONTENTS. 



PAGE. 

 I. Introduction 95 



II. Experiments with the Rose Aphid 97 



III. Experiments with other Species of Aphids 102 



IV. Period during which the Wing Development may be Controlled 104 



V. Strength of Magnesium Salts needed to Produce the Winged Aphids. . 105 



VI. Physical Factors: 



1. Temperature 106 



2. Wilting of the Plant 107 



VII. Morphological Studies 108 



VIII. General Discussion no 



IX. List of Aphids Experimented with 113 



X. Summary 114 



XI. Literature Cited 116 



I. INTRODUCTION. 



There are at least two closely related and equally interesting 

 phenomena observed in the aphids, or plant-lice as they are 

 commonly called. These are the development of apterous or 

 alate forms, or both, as the offspring of either a winged or ap- 

 terous viviparous female, and the parthenogenesis exhibited by 

 them. The phenomena are not the result of alternation of 

 generations, for it has been found by Slingerland (1893) and 

 others that under certain favorable conditions a species of aphid 

 might continue multiplying for a period of several years without 

 producing a single male or winged individual. 



Several attempts have been made to explain the phenomenon 

 of wing-development in aphids. Shortage of food supply, it is 

 believed, will usually produce winged aphids so that they may 

 fly away to other plants where the supply of food has not been 



1 A thesis submitted in partial satisfaction of the requirements for the degree 

 of Master of Science in the Graduate School of the University of California, April, 

 I9I3- 



95 



