86 MAINE AGRICUI^TURAL EXPERIMENT' STATION. 191I. 



Insectary Host Plant Tests for M. sonalifolii. 

 (July-October, 1907.) 



By planting potatoes in the insectary often, the plant lice 

 were supplied with fresh plants which were colonized by the 

 individuals which deserted the plants they had rendered sickly. 



Buckwheat was sown among the potato plants in the insect- 

 ary 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, de- 

 serting 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 contended progeny 

 upon potato, and shepherd's purse, and also upon the young 

 pea vines. Except for stray individuals which, of course, 

 would be found upon everything in the crowded insectary, the 

 buckwheat remained apparently untouched. Whether M. so- 

 lanifolii would have accepted the blossom tips of the older 

 buckwheat or not was not demonstrated, as the buckwheat, 

 although it lived, did not make much growth. 



October ii. Insectary search showed the Macrosiphum eggs 

 near some of the oviparous forms both upon potato and shep- 

 herd's purse (Capsclla Bursa-pastoris). Many of the eggs 

 were 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 migration 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 seek the fresh po- 

 tato plants almost as readily as the peas or the shepherd's purse 

 might seem to indicate that if a similar succession of new pota- 



