PINK AND GREEN APHID OF POTATO. 211 



Buckwheat was sown among the potato plants in the insectary 

 and about 200 young and clean plants of shepherd's purse were 

 put into trays. Peas were also sown at the same time. By 

 the time the buckwheat and peas were well up about 100 fresh 

 potato plants were available, and the M. solanifolii, deserting 

 the older potato stalks, colonized thoroughly the fresh potato 

 vines, pea vines, and the shepherd's purse apparently with no 

 preference. Both winged and wingless forms were found for 

 the rest of the season rearing contented progeny upon potato, 

 and shepherd's purse, and also upon the young pea vines. Ex- 

 cept for stray individuals which, of course, would be found upon 

 everything in the crowded insectary, the buckwheat remained 

 apparently untouched for feeding purposes. Whether M. solani- 

 folii would have accepted the blossom tips of the older buck- 

 wheat or not was not demonstrated, as the buckwheat, although 

 it lived, did not make much growth. (On vigorous succulent 

 buckwheat in the field a collection of apparently solanifolii was 

 taken at Houlton, Me., Aug. 31, 1907.) 



October 11, 1907. Insectary search showed the Macrosiphum 

 eggs near some of the oviparous forms both upon potato and 

 shepherd's purse {Capsella Bursa-pastoris.) Many of the eggs 

 were the glistening brownish black of well hardened eggs but 

 some were pellucid green, showing that they had very recently 

 been deposited. They were upon the plants indiscriminately on 

 leaves and stalks. Males and oviparous females were present 

 upon both these plants. 



The appearance of the oviparous females and the deposition 

 of eggs with the uncaged material at practically the same time 

 as that of the forms that had been prisoners for 2 months would 

 indicate that these dates are about normal. In the insectary 

 the dispersion from overcrowded potato stalks to fresh plants 

 seemed to take place irregularly and not at any stated times, the 

 condition of the infested plant apparently influencing these 

 movements. The fact that they seemed to accept the fresh 

 potato plants almost as readily as the peas or the shepherd's 

 purse might seem to indicate that if a similar succession of new 

 potatoes were supplied them in the field they might not seek 

 another host even there. As it is a wholesale migration has 

 taken place each of the seasons these plantlice have been under 

 observation. 



