Vegetable Plant Lice 5 



It is entirely probable, then, that the infestation starts with a 

 light infestation of winged migrants, which come in from roses and 

 weeds on which the early generations were passed, and that for a 

 period of several weeks there is rapid multiplication of the species 

 without the grower being aware of anything unusual. When the 

 lice have reached the point that there are many hundreds for each 

 potato and tomato plant, the plants begin to look sickly and the grow- 

 er finds to his amazement that they are covered with lice. 



About the time the potato and tomato plants are seriously dam- 

 aged natural enemies of the lice overtake them and those that do 

 not develop wings and leave the fields are destroyed. Although little 

 of a really definite character is known about their movements after 

 leaving the tomato and potato fields, studies made in the State of 

 Maine indicate that they may colonize a long list of weeds as well 

 as members of the rose family. 



Fig-. 2 



The Green Peach Aphis 



i — Adult winged female ; 2 — Immature female ; 3 — Adult wing- 

 less female 



Green Peach Aphis 



(Myzus persicae Sulz.) 



The green peach aphis, alias the spinach aphis, passes the winter 

 as a shining black egg upon the twigs and branches of peach, plum, 

 nectarine, cherry and possibly other trees, and various weeds. The last 

 possibility is mentioned because for the past several years this spec- 

 ies has been very abundant upon vegetables and scarce upon the 

 peach. 



