172 



Remedies for Apple Sucker. [jUNE r 



air, and soon settle down again nearly on the same spot. They 

 rest mainly beneath the leaves, and suck out the sap, causing, 

 the leaves to turn brown in patches, or sometimes to assume a 

 yellowish hue. 



The eggs are laid on the under sides of leaves, and hatch 

 out in about two weeks. The larvae are at first active and 

 spread over the leaves ; later on they become covered with a 

 pale scale, beneath which — in the cabbage snow fly (Aleyrodes 

 proletella) — two yellow spots are noticeable. In ten days the 

 larva turns into a pupa beneath the scale, and from this the 

 winged snow fly appears in four days. 



The adults, although they appear to be snow white, are not 

 so when the down is rubbed off them ; they are then seen to be 

 black, with some yellow about them. They breed in winter as 

 well as in summer. 



The only method of treatment that can be suggested is 

 spraying with paraffin emulsion, which would have to be done 

 several times at about ten days' interval, as the wash could not 

 be used of sufficient strength to destroy the scaly covering of 

 the maturing larvae and pupae. The delicate snowy white flies 

 would soon be killed by this wash, and also by the use of 

 caustic alkali wash in winter. The method of making paraffin 

 emulsion and caustic alkali wash is described in the two 

 following articles. 



The times when measures may be taken with best results 

 against the apple sucker are in the early spring and the autumn. 



The first spraying should take place with 

 ^Remedies^for^ paraffin emulsion just before bud bursting, 

 ( Psylla malt.) when the eggs are hatching, and a second 

 spraying should be undertaken after the 

 hatching, and when the young leaves have unfolded from the bud r 

 as at this time there would be a chance of reaching the larval 

 psylla. It is possible that occasional lack of success with the 

 spray may be due to the circumstance that the eggs have 

 already hatched, and that the young have penetrated the bud 



* An account of the apple sucker is given in the Board's leaflet, No. 16. 



