EHOPALOSIPHUM LIGUSTEI. 13 



coloured than others. Taken on Alisma plantago at 

 the Wanstead ponds. It feeds, however, on a variety 

 of other water plants, such as Butomus umhellatus, 

 Potamogeton natans, Hydrocharis morsus-rance, Lemiia 

 gihha. To this list Passerini largely adds. In some 

 years it attacks the leaves of the water-lily, Numphcea 

 alba, so vigorously that the plants on large sheets of 

 water disappear for the whole year. Occasionally it 

 is but too common at Hampton Court, but at other 

 years the Aphis is difi&cult to find at all. 



Passerini in his ' Gli Afidi,' makes Aphis ni/nq^hwcB 

 the type of his genus Siphocoryfie, but subsequently in 

 his ' Aphididas Italica3 ' he takes A. xylostei for the type 

 of that genus. 



As the water-lily Aphis certainly possesses frontal 

 tubercles, though they may be but small, I exclude the 

 insect from Siphocoryne, which does not possess them. 



Rhopalosiphum ligustri, Kalt. Plate XLI, figs. 4, 5. 



Aphis ligustri, Kalt., Koch. 

 Rhopalosiphum ligustri, Pass. 



Apterous viviparous female. 



Inch. Millimeters. 



Size of body 0-055x0'035 1-39X0-88. 



Length of antenna 0*060 1'52. 



,, cornicles 0*015 0"12. 



Globose, shining, smooth, convex, bright yellow or 

 greenish. Head broad. Frontal tubercles marked, 

 and almost gibbous in form. Antennal joints tipped 

 with black. Cornicles long and tipped with black. 

 Legs wholly green. Taken in July at Wanstead. 



Winged viviparous female. 



