Proceedikcs, 1!I24 33 



Stenocranus dorsaiis iFieh.i Slia\viiii;;in. 15/9/22. (W.D.i 

 Laccocera vittipennis \'an D. (ididnn Head. 17 7 2(). (W.D.) 



Family Chermidae 



Aphalara angustipennis (rawf. Duncan, 29/6/22. (W.D.) 



Psyllia alni var. americana (Crawf.). Sooke, 30/6/23. (W.D.) on 

 alder; Victoria, 8/9/22. (W.D.) on Cottonwood. 



THE ELM-CURRANT APHIS (Eriosoma ulmi L.) 

 BY R. Glexdenxin(;. 



Relationship and DisTixcrisiiixn Featxres 

 Tliis aphid is a doulilc host s]i('cifs and has a rather intcrestino- life- 

 history and relationship. 



In the <ienus Eriosoma (Schizoneura) there are at present known 

 some four or five species which use the various elms as primary or winter 

 hosts. These species have heeii hadly mixed in the past, but, now that 

 their complete life-histories are known, they are readily distinguishable. 



lanigera, Hausman, the cdiniiion woolly aphis of the apple, alter 

 nates normally between the American elm (U. americana) and apple. 



americana, Riley, spends the wintei- on American elm, and the sum- 

 mer on the root.s of the Junebei-ry (Amelanchier). 



rileyi, Thomas, spends its whole life on iht liark and twi^s of Amer 

 ican I'lm and nui;rates only lietween trees of the same species. 



lanuginosa, Hartig, has been recently co-related with pyricola (B. 

 and D.), and mig-rates from Eni;lish dm (campestris and vars. i lo tli ■ 

 roots of pear trees. 



ubni L. lias as its winter host English elm, and migrates in early 

 summer to currants and gooseberries, forming subteri-anean c(donies on 

 the roots. 



The se])ai'ation of these species on their sununer hosts is easy, as 

 apparently they are constant in their habits. 



On the elms they are also separable from ciich other without recourse 

 to their structural ditferences, which are rather minute. 



Key to Species of Eriosoma ox Elms ix Caxada. 



(hi Aiiiiricdii ilm — Rosette type of gall, leaves and twigs in 



continuous malformation lanigera 



