90 Second Repoi't on Economic Zoology. 



others in the base of the buds survive. The male is apteroiis, very 

 minute, blind, and yellow in colour ; they were found by I'uckton 

 under a scale when examining the contents of a number of galls. Thus 

 in this species we get a sexual generation, which 

 does not as far as we know occur in luricis. 



The sexually produced egg is always laid 



on the spruce, which is the primary food plant 



of the Aphis, which mn.st now apparently stand 



p • 20— W -rs o ^^ Chcrmci alictis-larieis. How far these two 



OP SUMMER GENERATION, luccs cau Hvc upou onc tree only is a matter 



at present unsettled. 



Dreyfus gives the following life-cycle : — 



First Year. 



Generation I. passes winter on spruce as C. ahldis and there 



lays eggs. 

 Generation II. develops in spruce galls and forms winged alndis 



in August. Part of these migrate to tlie larch and become 



luricis and lay their eggs on the needles. 

 Generation III. hatches on the larch and passes the winter 



under bark scales and in crevices. 



Second Year. 



Generation IV. These come from the eggs laid on the larch, 

 the product of III., \\'hich acquire wings at the end of May 

 and mostly return to the spruce, and their eggs produce 

 generation V. 



Generation V. consists of males and females. From the 

 sexually produced eggs there then hatch and develop the 

 mother queens, which live throughout the winter and corre- 

 spond to Generation I. 



Whether or not each race can live entirely on either the spruce 

 or the larch or whether a migration is necessary does not seem to lie 

 as yet settled. I am confident that the ahietis can go on year after 

 year on the spruce. One under observation became infected with the 

 Ghcvmcs in 1895, and since then the CJiermes have steadily increased 

 year by year. The nearest larch tree is more than half a mile away 

 in a straight line. This larch is annually covered with laricis. 

 That the spruce in question was quite free a few years ago I know, 

 and the first signs of A^^hidea 1 saw upon it were winged forms tliat 

 I could not separate from the winged larch species. 



