APHIDIDAE OF FORMOSA.— L 



BY 

 RYOICHI TAKAHASHI. 



if Entomological Assistant. 



INTRODUCTION. 



Among the more important insect pests of our economic plants 

 in Formosa are those of the family Aphidiae or plant-lice. 



IMost of the species are of no economic importance, t)ut there 

 are many wliich are well known pests of our cultivated crops. 



For example, Oregma lanigera (Zehntner) is a wide-spread pest, 

 of considerable importance, of the sugar cane. 



The cabbage aphis, Rhopalosiphmn pscudobrassicae (Davis) and 

 the cucumber aphis, Aphis niulvae Koch are regarded by native 

 growers as extremely troublesome pests, although they are easily 

 killed with an}' of the common contact insecticides. 



Aphis gossypii Qlov., Aphis medicaginis Koch, Toxoptera aurantii 

 (Boyer). JTyzus persicae (Sulz.) and Pentalonia nigronervosa Coq. are also 

 Well known pests in our island. 



These insects are kept well in check by theii- natural enemies, 

 such as tlie ladj'bird-beetles, the syrphid flies, the lace-wings, the 

 parasitic Hymenoptera, etc. 



(_)f the ladybird-beetles, pn^bably the most efficient in Formosa 

 are Coccinella 7-punctata L., Synonycha grandis Thunb,, Ptychanatis 

 a.dridis Pall, and Scymnus spp. 



( )f the syrphid flies there are many species feeding on plant-lice 

 in our island. Ghrysoixi formosae Mats, and Chrysopa boninensis Okam 

 seem to be the most common aphid enemies among the lace-wings. 



