1918-19.] Life-History and Bionomics of Myzus ribis, Linn. 93 
polita. They had already been severely parasitised by a hymenopteron, 
and a fortnight later had completely disappeared. During August and 
September I failed to find this species on any plant in the open. 
P. galeopsidis was first described by Kaltenbaeh in his monograph 
(16, p. 35), and the description does not differ fundamentally from that of 
M. ribis in the same work. He says that in the apterous forms, ribis is 
citron-yellow with a very short cauda, while galeopsidis is green and the 
cauda is “ small.” Further on he mentions that ribis is found under 
swellings on the leaves, and the explanation suggests itself that he wrote 
his account of ribis from the form from the red blisters, which, as I have 
Fig. 6. — The development of the frontal tubercles. Semi- diagrammatic. 
(a) Myzus ribis, winged $ from red blister. 
(b) „ „ ,, ,, green leaf. 
(c) „ ,, ,, first generation after transference to Galeopsis tetrahit. 
(d) Phorodon galeopsidis, Kalt. , winged $ from Galeopsis tetrahit. 
(e) Myzus ribis, & from currant. 
already shown, is yellow, and shorter in the body than the form from the 
green leaves. As regards the winged female, he says that the rostrum 
reaches to the second coxes in ribis, whereas in galeopsidis it does not; 
but in all the examples that I found on Galeopsis the rostrum is 
indistinguishable from that of ribis. Moreover, he continues that the 
first antennal joint is drawn into a strong tooth. This accounts for the 
subsequent inclusion of the species by Passerini in his genus Phorodon, 
which, as Buckton points out, differs from Myzus only in the possession 
of a tooth on Joint I. It will be seen from fig. 6 that no distinction can 
be made between the forms in this respect. Furthermore, Kaltenbaeh 
describes M. ribis with a large dorsal patch on the abdomen, and three 
