26 JOUENAL OF THE ROYAL HORTICULTURAL SOCIETY. 



with the marked structure of the wings, from the frog-hopper, one of the 

 Cercopidas often seen at this time on the trees. 



Treatment. — The usual treatment has been spraying with quassia and 

 soft soap or paraffin emulsion when the young are hatching out. The 

 best results have been with quassia and soft soap, but at best it is only 

 likely to lessen the amount of attack, for this wash must come in contact 

 with the actual insects to kill them, and as they do not all incubate at 

 once we must keep on spraying for at least two weeks to entirely eradicate 

 them. This, of course, on a large acreage would be impossible. 



Another time when contact washes may be theoretically used is in 

 winter to destroy the eggs. Some laboratory experiments have shown that 

 this wash corroded the eggshell, but repeated experiments in the field 

 have shown that it cannot be relied upon. The wash acts only at a 

 certain stage just prior to the hatching of the eggs. Nevertheless much 

 benefit has accrued to orchards where this wash has been repeatedly used, 

 so that it seems some benefit is derived from it. 



At present it cannot be advised as a preventive of Psylla. 



There is then only one other time when we can get at this insect, 

 namely in the autumn, and from some experiments made it was found that 

 a paraffin emulsion would kill many of the winged Psyllae, and thus we 

 can prevent egg-laying, and I cannot but feel sure that this will prove to 

 be the best means of attacking this insidious enemy. 



An emulsion of 1 gallon of paraffin and 10 lbs. of soft soap to 50 gallons 

 of water can safely be used at the time when the leaves are ripe and ready 

 to fall. 



Woolly Aphis. — The world-wide woolly aphis, or so-called American 

 blight, has been very evident this year, and has done much harm to both 

 Apple and Pear trees. One of its habits has been overlooked in this 

 country, and hence treatment is usually only temporarily successful. 



The woolly aphis differs from all other fruit aphides in that it has 

 no cornicles or honey tubes, and does not secrete that copious flow of 

 sticky matter which is so detrimental to the foliage and fruit. 



We rarely find the woolly aphis on the leaves, as we do other Apple 

 aphides ; its main object of attack is the wood, both old and young. Its 

 punctures produce swellings on the young wood, which split, and which 

 in time give rise to large distorted areas very similar to those produced 

 by the canker fungus. In these deformed growths the insect may go on 

 breeding all the year. 



One does not observe the aphis on the young wood during the cold 

 part of the year. Is it that they move down to shelter, or is this down- 

 ward movement connected with their migratory habit earthwards ? 



Many of the woolly aphides may remain on the trunk and boughs 

 during the winter in the active state. 



To ensure the continuity of the species, a few eggs are laid always 

 close to the ground. An oviparous female deposits but a single egg, and 

 her dried skin forms a shelter over it. This egg hatches out in the 

 spring. 



Not only does this plant-louse winter on the trunk of the Apple, but 

 frequently on the roots, there giving rise to a subterranean race which 

 works upon the roots in exactly the same way as the aerial form does 



