6 THE SPRING GRAIN-APHIS OR " GREEN BUG." 



Page. 



Embryology -. 94 



Methods and material 95 



General description of the egg 95 



Observations 97 



Summary of embryological development 102 



Natural enemies m. . . . 103 



Internal or true parasites 104 



Aphidius testaceipes Cress 104 



Description and identity 104 



Life history 105 



Oviposition 105 



Length of period from egg to adult * 106 



Effect of parasitism by Aphidius upon development of host. . 106 



Effect of parasitism by Aphidius upon fecundity of host 107 



Movement of larva within the host and manner of attaching it 



to the plant 109 



Fecundity 113 



Parthenogensis 114 



Hosts of Aphidius testaceipes 115 



Hibernation 117 



Influence of winds in the dispersion of Aphidius testaceipes 118 



Temperature influences of Aphidius 119 



Effects of wet weather on the diffusion of Aphidius 121 



Other species of Aphidius 122 



Aphelinus 122 



Notes on life history and habits of Aphelinus 124 



Secondary parasites 125 



Megorismus sp 125 



Aphidencyrtus aphidiphagus Ashm 126 



Pachyneuron sp 127 



Allotria sp 128 



Predaceous enemies 128 



Lady-beetles 128 



Syrphid flies 129 



Lacewing flies 132 



Cecidomyiidse 133 



Birds 135 



Miscellaneous enemies of Toxoptera 135 



Ants and their relation to Toxoptera 136 



Remedial and preventive measures 136 



Field experiments * 136 



Cultural methods 139 



Artificial introduction of parasites 142 



Literature consulted ? 144 



Index ' il45. 



