BULLETIN No. J47. 



THE POTATO PLANT LOUSE. 



Xcctarophora solanifolii Ashmead. 



Edith M. Patch. 



On account of their extremely small size, aphids or plant lice 

 are to a great extent unnoticed, but when conditions are favor- 

 able to their increase there are many species of these minute 

 creatures that are capable of bringing devastation to the vege- 

 tation which they frequent and staple crops often suffer severe 

 attacks. The hop plant louse, the several aphids of the apple, 

 the spring grain aphis, the corn aphids, the melon aphis, are, 

 for instance, pests of tremendous importance ; and the destruct- 

 ive green pea louse alone is estimated to have caused a loss of 

 $7,000,000 during the two seasons of 1899 and 1900 just along 

 the Atlantic Coast States. During the past 4 years many spe- 

 cies of aphids representing 14 genera and living upon about 90 

 species of plants and trees have been collected for the Maine 

 Agricultural Experiment Station and some few of these have 

 been given special study. Of these the potato plant louse, 

 attacking as it does one of our chief crops in Maine, and pre- 

 senting in its life history certain points which may be of signifi- 

 cance in connection with closely related species, has seemed of 

 sufficient importance to record somewhat fully. 



Economic Sigxificaxce. 



During the summers of 1904, 1905 and 1906. enormous num- 

 bers of the plant louse, N. solanifolii, appeared over wide areas 

 in Aroostook County, the potato vines being attacked to an 

 injurious extent in the vicinity of Houlton and elsewhere. The 

 colonies cluster thick on stem, leaf and blossom stalk, blighting 



