ArHIl>Ii:)J3 UF FORilUSA. Ill 



Rlfiis javauka : the lower surfaces of the leaves are a'tacked. The apliis 

 may be seen ou tliis plant from Mai'ch t.j September, the gi-eatest abuudauce 

 ijcciUTirig in cases from the latter part of ^larch to the eud of June, but its 

 numbers are gi-oatlj reduced during the summer and antuiun, at which seasons a 

 fe^v wingless forms group together ou the lower surface of the midribs of the 

 leaves, often I eiug covered with tents by the ants. 



(Saasou when the insect is common) 



Near Taihoku it is common fi'om about March to June. 



(Winged viviparous female) 



Tlie winged fi'oms are very common almost at any season. 



(Male and oviparous female) 



Near Taihoku this aphis seems to be continuously viviparous during the 

 year, without producing the sexes, since I have observed the viviparous females 

 in Februar}-. 



(Intermediate) 



No intermediates have been observed. 



(Distribution) 



Formosa : Taihoku, Shinten, Ural, Shiriu, Tansui, Shiuchiku, Kwaushiroi, 

 Shinkwa. 



B. Obseiwations near Tokyo. 



(Host plants) 



Bhus jovrmici : the aphis inhabits this plant from the Ivgiuniug of May 

 to about August. 



Viburiuiia sieholdi : the apliis may be seen on this plant fi-om April t) 

 September. 



(Season when the insect is abundant) 



It is nne of the most common species near Tokyo, the greatest abundance 

 taking place in May and June, but its numbers arc conspicuously reduced 

 from Augitst onwards throughout September. 



(Winged vi\-iparou3 female) 



The wiugel froms make their appearance fi-om about tlio 10th day of 

 May onwards to September. 



(Male and oviparous female) 



The \viuged males and wingless oviparous females make their appearance 



