ArHIDlD.li: OF FORMOSA. 107 



(CommiTual life) 



Tills species is sometimes fuuml with PlnjUapJioidea liamlmslcolt Tak;i]i. in 

 groups ueav Taihoku. 



(Habit) 



It is Terr inactive and does not liave the habit of moving the posterior 

 pair of legs when disturbed. 



(Distiibutioii) 



Formosa: Taihoku. Urtii, Kagi. 



Japan : Tokyo. 



Aphis maidis Fitch. 



(H._.st plants) 



Zea iiicnjfi : the upper and lower surfaces C)f the leaves are attacked. 



Hordeuia sativir/ii : some plants of the Gramineae. 



Oryui sativa : some wingless vivip;U'ou5 females were observed on this 

 plant indoors on April 10 and 13, 1922, near Taihoku. 



Near Taihoku the viviparous females ruay be seen throughout the ye;u-, 

 rarely occiUTiiig in great uumljers. The winged forms are not uncomujon, and 

 the sesuales have never liaen observed. 



Near Tokyo the apliis was t)bserved from Jime to Septemlier, 1919, during 

 which peril id the viinged forms were produced from time t> time. 



Aphis formosanus Takah. 



(Host plants) 



Zca mays : the leaves suffer severe injury fi-om this pest. 



SmrjJnm vuhjarc : the lower surfaces of the leaves are attacked and the 

 infested leaves are withered. 



Some plants of the Graminca- : the under smfaces of the leaves are attacked. 



(Oliservations near Tokyo) 



The fuithor has obseiTed continuously some colonies on the Zai mays 

 fi-om the last of July to the last of September, 1917, during which period 

 many winged fonas were produced from time to time, and the aphis was 

 always almndant. 



