ANIMALS INJURIOUS TO FRUIT TREES. 23 



and wilted appearance. As a result, large quantities of the nuts, 

 apparently quite sound, fell off later in the season. 



Unlike most aphids this species lives upon the upper surface of 

 the leaf. Its life-history is only imperfectly known. 



On large trees, such as those this pest occurred on, spraying is 

 only partly effective, as it is almost impossible to reach the upper 

 branches, and as those are killed below, fresh migrations from above 

 take place. 



The most effective treatment in this case proved to be the follow- 

 ing : in August a large quantity of dried weeds and other rubbish was 

 piled up and set on fire beneath the trees on a still day ; it smouldered 

 for some length of time, and the following morning millions of dead 

 and dying aphids were to be seen on the ground beneath the trees. 



This method would probably prove still more effective in the case 

 of the common walnut aphis (Pterocallis juglandicola, Kalt.), which 

 lives on the under-surface of the leaves. 



THE MEALY PLUM APHIS. 



Hyalopterus pruni, Fab. 



Early in June examples of this obnoxious pest were received from 

 a Worcestershire orchard, where it was present to an unusual extent. 



The insect is easily recognisable by its pale green colour and the 

 mealy secretion covering it. The direct injury to the leaves varies. 

 I have seen trees badly attacked, on which the leaves at an early date 

 commenced to turn yellow and fall off, whilst in other years trees 

 equally badly attacked did not seem to suffer. The large quantity 

 of honeydew which the insects secrete often does the most harm, as 

 it falls from off the leaves on to the fruit, turning into a sticky black 

 mass. 



The life-history of this species is only imperfectly known. They 

 usually make their appearance on the plum trees in June and July, 

 disappearing again in the early autumn. Walker was of opinion that 

 this species was the same as that he found on reeds, etc., Hyalopterus 

 arundinis. 



Spraying with paraffin emulsion, to which i Ib. of potassium 

 sulphide has been added to every 100 gallons of the sprayfluid, has 

 proved a successful remedy. 



