REPORT OF SOCIETY . 45 



THE POTATO PLANT LOUSE 



By Omer Caron, B.S.A., Assistant Entomologist, Province of Quebec. 



When asked by a director to prepare a paper for this meeting, I decided 

 to speak of a pest that gave me trouble the past 3'ear, since it raged in the dis- 

 trict where I happened to be. 



I feel that it will be somewhat difficult for me to interest a meeting of tech- 

 nical entomologists such as this one. For this reason I shall be brief and shall 

 content m^^self with a discussion of some matters of a practical nature. 



A few words regarding the Potato Plant Louse, called by the scientific name 

 of Macrosiphinn solanifolii : 



This bug, with which the public is not ver^' familiar, is not unknown to ent- 

 omologists. In the L'nited States it has been described at length and studied in 

 those sections where it has done damage. The best descriptions help us but 

 little however, to identify' it, since it resembles very closeh' members of other 

 species. The variety that interested me was the green variety. These plant 

 lice, like others of the family, comprise wdnged and wingless, viviparous females, 

 oviparous females and winged males. 



My observations were made on the farm of the School of Agriculture, Ste. 

 Anne de la Pocatiere where I was in charge of potato spraying. The damage 

 caused last summer was considerable. The plant lice attack by preference healthy 

 and strong plants ; in a few days infested plants wilt, turn brown and dr}' up 

 very quickly. It was evident that as a result the growth of the tubers was 

 arrested. Happily the ravages of the insects did not extend ver}' far beyond 

 the limits of the farm, for an invasion of this kind is more to be feared than 

 the ordinary invasions of the potato beetle. The latter can readih' be com- 

 batted bj' the ordinary means, but in the case of the plant lice, a more complex 

 treatment is necessary. 



The plant lice are sucking insects and they do not feed on the upper surface 

 of the leaves, but on the lower. It was necessar}', therefore, in order to reach 

 them, to use an apparatus directing a jet of spray on the under surface of the 

 leaves, and as this operation has not been satisfactorily accomplished for Bor- 

 deaux applications, better results were not secured in this case. 



The invasion of which I speak took place in the second part of the summer, 

 that is about the 10th of August. 



The plant-louse vmder consideration does not confine its attacks to pot- 

 atoes ; when it is found near fruit trees, I have often met it on them. On fruit 



