ArUIDID.TS OF FORMOSA. QQ 



Field observations on some Aphididse 

 in Formosa and Japan. 



The observations of the followiug p;xgo3 were made by the author near 

 Tokyo from 1916 to 1920 and near Taihoku from 1920—1922. 



Macrosiphum gobonis Mats. 



(Host plants) 



Ardium lappa : only the nuder snt'aces of the leaves are attacked, the 

 injury uot being severe. lu Japan this species often occurs in very large 

 numbers ou this plant, but, in Formosa, it is quite rare. 



Cirsium Joponicum : the stems are uifested. Neai' Taihoku this insect 

 may be seen on this host from November to June, most abundantly from 

 January to April, while near Tokyo, it is uot uncommon ou the host from April 

 to October. 



Crcpis Joponica : a few wingless viviparous females were found attacking 

 the stem in March 1921, near Taihoku. 



Samsurca affiiiis : the stems are attacked. I have observed many wiuged 

 and wingless viviparous females in March and April, 192 J, and in April, 1922, 

 near Taihoku. 



(Season wheu the insect is abundant) 



lu Formosa this louse is abundant fr'om January to April and is extremely rare 

 from Jirly to October, while near Tokyo it Ls vei'y common from April to October. 



(Wiuged viviparous female). 



The wiuged viviparous females are \^^vy common in Formosa, as well as 

 in Japan. 



(Male and oviparous female) 



In Formosa this aphis is viviparous throughout tlie jear, without pro- 

 ducing the sexual forms, which, in the vicinity of Tokyo, occur frum the beginning 

 of November. 



(Intermediate) 



Only a brachypterous viviparous female has been collected by the author 

 in December, 1917, near Tikyo. 



