248 Insect Pests. 



small twigs and buds. In this position they remain until the buds 

 of the damson burst in spring. The earliest date I have noticed them 

 hatch out is the 29th of March. That is later than the hatching of 

 the true plum aphis. 



Not only are these ova laid on the damsons and now and then 

 plums, but also in numbers on the sloe ; in fact, the damson and sloe 

 are most affected. During the autumn vast swarms of the hop aphis 

 cover the leaves of all prunes, yet but very few eggs are detected on 

 plum trees and greengage, whilst the damsons are literally covered. 

 If damsons and sloes exist in the neighbourhood they are used as 

 winter egg quarters in preference to any other prunes. The planting 

 of damsons without any necessary checks has been a means of increase 

 for the hop aphis. On these trees the ova hatch out in spring into 



FIG. 181. HEAD OF VIVIPAltors FEMAI.K OF TIIK HOP-DAMSON APHIS (I'honidoil lilltlUlli). 



(Greatly enlarged.) 



lice, which speedily grow into wingless and viviparous females ; these 

 are sometimes spoken of as " queen- " or " stem-mothers." These 

 wingless females produce living young like themselves, and suck 

 out the sap of the young damson leaves, often causing untold 

 damage, and the blossom may suffer. They can at once be told 

 from the Plum. Aphis (A prv/ni), by the small processes on the 

 head shown in the figures. Some authorities have considered this 

 prune-hpp aphis a distinct variety, known as variety malahcb ; there 

 is no reason for giving it another name, it is the same aphis, 

 although the antennal swellings are not so developed on the damson 

 as when it is on the hops. On the prunes there seem to be normally 



