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Patch (Edith M.). Pink and Green Aphid of Potato {Macrosiphum 

 solanifolii, Ashmead). — Maine Agric. Expt. Sta., Orono, Bull, 

 no. 242, October 1915, 20 pp., 3 figs. [Received loth Februarv 

 1916.] 



Aphids with only one food-plant are comparatively easy to control ; 

 those with two present certain difficulties, but when, in addition 

 to two favourite food-plants, a species of Aphid will accept others 

 not botanically related, the problem of control is complicated by a 

 new element for every different food-plant. This is the case with 

 Macrosiphum solanifolii, Ashmead. At the time that work with 

 this species was first undertaken at the Maine Station, the only 

 food-plants recorded for it were Solannm jasminoides and the 

 potato. The following list is now given : Zea mays (maize), Ii'is sp. 

 (cultivated), Gladiolus sp., Fagopyruni esculentum (buckwheat), Cheno- 

 podium album (white goose-foot), Amaranthus retrojlexus (red-root 

 pigweed), Brassica rapa (turnip), Capsella bursa-pastoris (shepherd's 

 purse), Pyrus oiialus (apple), Rosa sp., Phaseolus vulgaris (bean), 

 Pisum sativum (garden pea), Physalis sp. (ground cherry) Solunmn 

 jasminoides (pepper vine), Solanum 7nelongena (egg plant), Solanum 

 tuberosum (potato), aster (cultivated). Cineraria sp., Lactuca sp., and 

 Sonchus oleraceus. In the spring, M. solanifolii is found on rose 

 bushes, in special abundance near the flower buds. Both wingless 

 and winged individuals migrate to potato plants, the former by flying 

 and the latter by crawling, if near enough. In Maine this usually 

 occurs in the first half of July. On the potato the Aphids increase 

 enormously and often before the end of August cover the tender tips 

 and blossom stalks with their colonies. By mid-September the 

 autumn migration is over and the Aphids have deserted the potato 

 fields. They then prefer roses, but will form colonies upon a variety of 

 plants, some of which are common weeds. The last generation of the 

 year consists of the wingless, egg-laying females and the winged males ; 

 these appear in Maine about 26th September and only at this time, all 

 the other generations consisting of viviparous females. The insectary 

 observations of 1907 showed that under indoor conditions the true 

 sexes may be produced and the over-wintering eggs may be deposited 

 on both potato and shepherd's purse ; it is likely that this generation 

 can be produced on other accepted food-plants also. No evidence has 

 been found in the field, however, that the true sexes or eggs occur 

 normally upon the potato, for the Aphids leave that food-plant earlier 

 in the season when out of doors. It is not known upon how great a 

 range of food-plants M. solanifolii will develop in the spring. In 

 Maine it has never yet been collected during this season upon anything 

 but rose, which would indicate this to be the favourite overwintering 

 host-plant and the one ordinarily chosen for oviposition in the autumn. 



As regards the economic importance of this Aphid, an attack of less 

 than two weeks' duration suffices to kill the potato stalk for a distance 

 of 4 to 6 inches from the tip, and the growth of the tubers on plants 

 thus weakened must necessarily be affected. Apart from this, the 

 wounds afford a favourable entrance for bacterial or fungus disease. 

 The honey -dew formed when Aphids are abundant is soon attacked by 

 a dark fungus, which must interfere with the natural function of the 

 leaves. M. solanifolii has been recorded from Canada, Florida, Maine 

 and California, and from various intermediate localities. Autumn 



