New Zealand Department of Agriculture.

Manawatu Herald, 28 March 1896, Page 3

New Zealand Department of Agriculture.

JOBN D. EITCHIE, Secretary. USA FLETS FOR GARDENERS AND FRUITGROWERS, NO. 12.

BLACK APHIS, BLACK FLY (%^»m). By T. W. Kirk, F.L.S., &c, Lond., Government Biologist. Fig. 1. Small branch of peach-trea, showing both winged and wingless forms of the insect: natural size from nature. Specimens received from Onehunga, Auckland. Last season some excitement was it does extensive damage to various caused in Auckland by the discovery orchard trees, sach as cherry, peach, of a supposed new orchard post Japanese plum, &c, and is one of attacking Japanese plums, &c. the hardie3t and most difficult of the Specimens were received from several family to deal with. correspondents, and the most cursory The figures 2to 6 are all copied examination showed that the insect from Buckton's " British Aphides," was no new importation, but a very for, although the specimens obtained old acquaintance—namely, the black last year differed in some very small aphia {Myzw ceraai), known to particulars from the descriptions of gardeners in this colony for probably that famous authority, there is not thirty years past. the slightest doubt of its identity, This insect is in many parts of the and it was thought best to reproduce world dreaded by fruit-growers, aB the typical forms.

These and other Aphides some* times make their appearance in such enormous number? as to border on the miraculous. In this connection, and in order to give a general idea of the life-history of plant-lice, it may be well to quote the brief account by Dr Harris :— "Aphides, or plant-lice, as they are usually called, are among the stoat extraordinary of insects. They are found upon almost all parts of plants,— the roots, stems, young shoots, buds, and leaves,— and there is scarcely a plant which does not harbour one or two kinds peculiar to its«lf. They are moreover, exceedingly prolific, for Reaumer has proved that one individual, in five generations, may become the progenitor of j Dearly six thousand millions of descendants. "It often happens that the succulent extremities and stems cf plants will, in an incredibly short space of time, become completely coated with a living mass of these little lice. These are usually wingless, consisting of the young and of j the females only; for winged individuals appear only at particular seasons, usually ' in the autumn, but sometimes in the spring i and these are small males and larger females. After pairing, the latter lay their eggs upon or near the leafbuds of the plant upon which they live, and, together with the males, Boon afterwards perish. "The genus to which plant-lice belong it called Aphis, from a Greek . word whioh signifies " to exhaust." The following are the principal characters by which they may be distiHgnfshed from other insects : Their ; bodies are short, oval, and soft, and j are furnished at the hinder extremity with two little tebes, knobs, or pores, from which exude almost constantly arinate drops of a fluid as sweet as honey ; their heads are small, their • beaks are tery long and lubu ar, ' their eyes are globular, but they have not eyelets ; their antennae are long and very slender, and there are only two joints to their feet. Their upper are nearly twice as large as the lower win^B; are much longer than the body, are gradually widened towards the extremity, and nearly triangular ; they are almost vertical when at rest, and cover the body above like a very sharp-ridged roof. "The winged plant-lice provile for a succession of their race by stockin^Le plants with eggs in t'io autumn, as before stated. Thes? a c batched in due time in the spring, and the young lice immediately beg n

to pump up sap from the tender leaves and shoots, increase rapidly * in size, and in a short time come to maturily. In this state it is found that tha brood, without a single exception, consists wholly of females, I which are wingless, but are in a con- j! dition immediately to continue their ' kind. Their young, however, are not hatched from eggs, but are produced alive, and each female may be j the mother of fifteen or twenty young lice in the course of a single day. The plant-lice of this second generation are also wingless females, which grow up and have their young in due time ; and thus brood after brood is a, produced, even to the seventh gene- h ration or more, wiLhout the appear- a ance or intervention, througout the t! whole season, of a single male. This extraordinary kind of propagation a end in the autumn with the birth of si a brood of males and females, which " in due time acquire wing 3 and pair. 0 ' Eggs are then laid by these females, tl and with the death of these winged tl individuals, which soon follows, the Sl race becomes extinct for the season." z " The Aphides infest every part of b the plant — root,' branch, shoots, ti leaves, and young fruit— in incredi- L ble numbers, and, as the whole of their nourishment is obtained by piercing the bark or leaf, inserting the beak or rostrum and sucking up rj the juices, it may readily be seen b how very exhausting to a plant a t< severe attack must be. p In New Zealand these insects ° make their appearance in early j spring (August and September), but h do mo3t harm when the trees are in o bloom, and whon the foliage and f( fruit are young. It is not necessary here to give a q description of each form ; the draw- . ings are sufficient for present purposes. \ The larvae of various species of Syrphuß flies and ladybirds destroy - an immense number of these Aphides. (See Leaflet on " Friendly In* sect 9.") Preventives and Remedies. — For destroying the root form of peach aphis, while the tree is dormant re- . move a little of tho surface soil, and I pour over the roots three or four j J gallons of sulphate-of^copper mixture ! usiug half an ounce of sulphnte to the gallon of water. Or, in districts whero tobacco is growj, the diggingin of waste tobacco-dust and stems around the tree is on excellent remedy. As a preventive, nnd to destroy the post;, spray the trea just before growth starts with a solution of sul-

phate of pottassium, loz. to tl gallon of water. Spray also a secor time just after the fruit is set. Tobacco, quassia, and soft-soap foz of each to the gallon of water or weak kerosene emulsion, 1 part I $5 oi warm water. There are numerous other remi dial measvis advocated, but tl above are the moat simple. I h&\ the authority of our Pomologist tht they have proved efficient. Kerosene emulsion is made as fo lows: Take kerosene, 2 ge.llons common soap, £ib ; boiling water, gallons. Melt the soap in the wate; which should by preference be rair water. Hard water is not suitable if only such is to be had, make : soft by adding some soda. Whe the soda has dissolved, pour th solution into the kerosene and the roughly churn up with a syringe, c in an old churn, for ten or fiftee minutes. The emulsion then c' oulc if perfect, form a cream, whic thickens on cooling, without any ap pearance of free kerosene. Another good formula where skim milk is plentiful is as follows : Kerc sane, 2 gallons ; milk (sweet or sour 1 gallon. Churn together ten c fifteen minutes, as above.