This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
This insect (fig. 347) is found in most Apple orchards in Great Britain and Ireland, and is frequently the cause of much damage. It is one of the sucking-mouthed insects belonging to the Hemiptera. The adult is a small green insect 1/10 to 1/8 in. long, with four transparent wings. Both sexes are winged; the males become more brightly coloured in autumn. They can be told by their skipping movements and clear wings. The females lay eggs from September to November; they are small yellowish bodies, yet discernible by the naked eye, and are placed along the leaf-scar ridges, amongst the fine hair on the shoots, and even in crevices in bark; the eggs have fine tail-like processes. They remain on the trees all the winter, and hatch out just as the buds are swelling and are ready to burst; the small flat louse-like young soon enter the buds and commence to suck away the juices. Later, they become green flat nymphs with wing buds, and these hatch out into the adult suckers in June. Both larvae and nymphs pass out long pale-blue or white threads from their bodies, and attached to these little threads are opaque oily globules. These, if we see them at the bases of the blossom trusses, where the larvae feed on the stalks of the blossoms, or on the leaves, where we more usually find the nymphs, are sure signs of Psylla attack. The attacked trusses of blossom turn brown and remain on some time even into the winter.
Treatment consists of (1) spraying with lime-and-salt wash, made as follows: - 1 1/2cwt. fresh slaked white lime, 20 lb. salt, 100 gall, of water. This should be done as late in February as possible, or the first week in March. Many eggs are thus prevented from hatching out. (2) Spraying as soon as the trusses are opening out with (a) nicotine wash at rate of 1 1/5 oz. 98 per cent nicotine to 10 gall, of water, or (b) quassia-and-soft-soap wash at rate of 8 to 10 lb. of quassia, 6 to 8 lb. of soft soap, to 100 gall, of water. [f. v. t.].
It is only comparatively recently that this little insect has got itself into notoriety. Either its ravages were put down to some other cause - perhaps that broad-backed bearer of so much imputed guilt, the east wind - or else it had not propagated its species to such an extent as to cause noticeable damage. Now, however, it is able to create a serious disturbance of an Apple grower's prospects. A row of Apple trees given over to their ravages looks after a week or two of the experience as if scorched by the Sirocco.
Fig. 347. - Apple Sucker (Psylla malt) 1 and la, Pupa. 2 and 2a, Imago (nat. siz: and magnified).
Some sorts of Apples are more susceptible to the attack than others. "Ecklinville Seedling", "Gladstone", and "Devonshire Quarrenden" are among the worst. " Lord Grosvenor", " The Queen", " Lane's Prince Albert" will crop merrily, when the varieties first mentioned are browned, dejected, and fruitless on account of the Apple Sucker.
Various remedies are recommended. It was claimed for some winter sprays that they possessed the power of destroying the eggs; that claim has gone to the limbo of unfulfilled intentions.
The lime-and-salt spray is much believed in by some advisers of the fruit grower; whether any who have tried it remain true to the faith, it is perhaps too soon to know. It is claimed for this spray, or rather wash, that it seals up the embryo sucker in his egg, and thus makes it his tomb, and also that it cleans the tree of lichen and other harbours of hibernating insects. One thing is certain, it is a most unholy preparation to handle, and the grower who himself puts it on his trees deserves a certificate of immunity from all pests for years. [W. g. l.]