PESTS 89 



salt wash has also been found to stop the young of 

 the former (and commoner) species from hatching. 

 Excellent results have been obtained, even after the 

 leaves have become curled, with nicotine wash. 



The Mealy Plum ApJds {Hyalopterus pruni), — This 

 is quite a different aphis from those mentioned above, 

 and does not curl the leaves, though it collects beneath 

 them in dense mealy masses. These plant-lice form 

 much gummy honey-dew, which falls on the leaves 

 beneath, and also spoils the fruit for market. They 

 make their appearance on plums in the summer, and, 

 later in the season, winged forms arise, which then 

 migrate elsewhere, though where they go, and whence 

 they come from to the plums in the first instance, we 

 do not know at present. 



Remedies. — A weak emulsion, preferably one con- 

 taining potassium sulphide (24^^), kills this aphis. 



The Hop-Damson Aphis {PJiorodon hicmiili). — This 

 aphis — the hop blight aphis or " fly " — passes the 

 winter in the egg stage in the axils of the buds of 

 wild prunes (sloe, buUace), and also of the damson^ 

 but very rarely in those of plums. It leaves the 

 damsons, etc., from mid May to early June, and flies 

 to the hops. It is greenish in colour, and can at once 

 be recognised by the horn-like protuberances on its 

 head and at the base of its feelers. 



Remedies. — Weak emulsion (16/;, i6d) should be 

 applied to the damsons, etc., late in April : when 

 hops have to be treated, soft soap and quassia (28), 

 or nicotine solution (26), must be used. 



