The ability of earthworms to spread over large continuous areas is restricted by the specialised habitat preferences of species. Slow spread by their own efforts must have been mainly responsible for their dispersal from the original points of entry into the New Zealand mainland. In the process of spreading, closely defined habitat preferences have become established and consequent specialisation has been responsible for the evolving of new species. Litter-dwelling earthworms and topsoil earthworms that emerge from their burrows at night and move freely about the surface, spread rapidly throughout areas with suitable environmental conditions. The larger subsoil worms would necessarily spread more slowly, yet one such species, Octochaetus multiporus, which can tolerate a wide range of environmental conditions, is found from Manawatu Gorge south-ward and is common in all South Island districts east of the Main Divide and in Stewart Island. Much of this area would have been unsuitable for earthworms in comparatively recent glacial times. Transport by birds and floating organic debris are means whereby dispersal has been assisted and, since most earth-worms can live for a time in fresh water, dispersal is expedited within a river system.

Two subfamilies of the family Megascolecidae are recognised in the native earthworm fauna, the Acanthodrilinae and the Megascolecinae, and these have dissimilar distribution patterns. The Acantho-drilinae are distributed throughout New Zealand while the Megascolecinae are confined almost entirely to northern and western districts. The most prominent break in the distribution pattern is south of Auckland where a northern fauna dominated by megascolecine genera (in particular the genera Megascolides) gives way to a fauna dominated by acanthodriline genera. During early Pleistocene times the ignimbrite eruptions which covered the central North Island presumably destroyed the vegetation and associated soil fauna, and successive volcanic outbursts have helped to maintain a barrier between the Auckland area and those further south. In the central North Island area there has developed a fauna dominated by a few species, each of which is widely distributed within the area and is to be found in one or more adjacent areas.

From the evidence of known distribution it is most likely that the native earthworms came originally from the Indo-Malayan or Australian region and entered New Zealand across a land-bridge connection from the north. They probably arrived in at least two waves, the first (subfamily Acanthodrilinae) in Cretaceous times and the second (subfamily Megascolecinae) in Tertiary times.

The aquatic “earthworms” have apparently been derived from terrestrial ancestors and have secondarily adopted aquatic habits. They should not be confused with a number of families of small Oligochaeta collectively known as the “microdrili” and which are primarily aquatic animals.

Two native species, Diporochaeta aquatica and Pontodrilus lacustrus, have been collected from deep water, the former in Lake Manapouri and the latter in Lake Wakatipu. They apparently swim freely in the lake waters and feed on organic matter suspended or sinking through the water. The apparent absence of similar aquatic worms from other New Zealand lakes may be due only to lack of suitable sampling.

Four species, Decachaetus violaceus, Diporochaeta chatamensis, Eodrilus paludosus, and Perionyx helophilus, have been collected from swamps and bogs. The first two have been recorded only once, whilst the remaining two have been collected from various habitats including swamps. It cannot therefore be said that any native species are undoubtedly confined to swamps. The anaerobic conditions typical of subsurface horizons of swamps and bogs would prevent earthworms from living anywhere but very close to the surface.

Much work on the distribution and manner of dispersal of earthworms has been based on the assumption that they are unable to survive immersion in salt water, even for a short period, and consequently cannot have been transported across the sea by rafting. A number of native earthworms, however, live in the intertidal zone of seashores under stones and debris or in brackish water. Of seven species collected from such habitats, five (Microscolex aucklandicus, M. campbellianus, M. macquariensis, Rhododrilus cockaynii, and R. leptomerus) are found under stones and logs and in the soil under tussocks, forest, or other vegetation, as well as in the intertidal zone. They are therefore well fitted for the colonisation of the isolated sub-Antarctic islands on which they are found as the dominant section of the earth-worm fauna. Pontodrilus matsushimensis var. chathamianus, a Chatham Island seashore worm, is a local variant of a species widely distributed on the shores of Pacific islands.

Despite the limitations imposed by their environmental requirements, earthworms occupy a wide range of habitat but, as their name implies, have achieved their greatest success as soil-dwelling animals. The prolonged geographical isolation of New Zealand and the predominance of forest vegetation have resulted in the development of a forest-earthworm-fauna with species highly specialised to occupy particular ecological niches in particular types of forest, and there is an obvious stratification into leaf-mould, topsoil, and subsoil groups. The leaf-mould species are small, active, and heavily pigmented. The smallest is 15mm long and the largest 180 mm but most are between 20 mm and 50 mm. They do not make permanent burrows but move around freely in the loose material just as arthropods and other animals do; hence they are more prone to capture by predatory birds and are more frequently exposed to ultraviolet light than those species inhabiting topsoil or subsoil. Their ability to move quickly gives some protection from predators and their heavy and varicoloured pigmentation affords some protection from ultraviolet light and provides a degree of camouflage. Thirty-six species are found almost exclusively in leaf mould; most are confined to relatively small areas but at least four species (Diporochaeta obtusa, D. punctata, Neochaeta forsteri, Plagiochaeta sylvestris) are widely distributed.

Both the topsoil and the subsoil dwellers have two distinct methods of making burrows in which to live. In the first method soil is swallowed and subsequently cast either at the soil surface or in natural cracks and cavities in the soil and in deserted burrows. In the second method the anterior end of the body is extended and inserted in spaces between the soil particles and then, by contracting the longitudinal muscles, the body is expanded laterally, compressing the soil to form a burrow. Usually burrowing consists of a combination of these two methods, the former predominating in more-compact soils and the latter in less-compact soils. As a burrow is formed it is lined with slime and thus has smooth walls firmly compacted by the lateral pressure applied during its construction.

The topsoil species are generally larger than leafmould species, the smallest is about 25 mm and the largest 300 mm but most are between 75 mm and 200 mm. They are not as heavily pigmented, nor do they move as rapidly as the leaf-mould species. In most species the body is circular in cross-section but in some (especially in Maoridrilus spp. and Neodrilus spp.) the body is almost square in cross-section with pairs of chaetae on the four corners and with thick body-wall muscle layers. Such species are generally the most active. Topsoil earthworms generally make shallow permanent burrows which they leave either at mating time or in order to forage for the food which they take back into their burrows. Most species appear to continue burrowing outside the confines of their living space and apparently live, to some extent at least, by ingesting soil and digesting the organic matter contained in it. Forty-eight native species are found almost exclusively in topsoil. A number of them found in tussock grassland areas (species of Rhodo-drilus in central North Island, and Maoridrilus in eastern South Island) are widely distributed, but most other topsoil species are confined to small areas.

Subsoil earthworms are usually large, sluggish, and unpigmented. The smallest is 32·5 mm and the largest 1,400 mm, but most are between 100 mm and 400 mm in length. The majority are circular in cross-section and have weakly developed body-wall muscles. They occasionally come to the surface or near to the surface for food, but otherwise are found only in the subsoil. They make very extensive burrows extending both laterally and vertically in the subsoil and occasionally going up into the topsoil. (Burrows of Spenceriella gigantea have been found about 20 mm in diameter and still continuing downwards at a depth of 11 ft 6 in.) They appear to make these burrows to obtain food by ingestion of soil and not primarily for shelter, like the burrows of the topsoil species. As they move forward they may deposit castings in the section of burrow left behind and it is not uncommon to find burrows partly filled with subsoil castings.

Earthworms are frequently found under logs and stones, under the bark of dead trees, in rotting logs, and in the litter of epiphytes in the axils of branches of trees. Most of these are species normally found in leaf-mould or topsoil and, more rarely, in subsoils, but one, Megascolides suteri, is found almost exclusively in rotting logs and is able to digest decaying fragments of wood. Ten species recorded from the Auckland Islands have all been found under logs and stones. Most of the ground is covered with acid peat (pH3·6–4·6) which is an undesirable habitat for these particular species.

The external features of the native earthworms are illustrated in the following diagram. Their size is extremely varied; the largest, Spenceriella gigantea from North Auckland, attains a length of 4 ft 6 in. and a diameter approaching ½ in., while a number of the smaller species are from ½ in. to 1 in. long and less than 1/10 in. in diameter. Most of the native species are red or brown. The red colour is sometimes due entirely to the haemoglobin of the blood showing through the epidermis, but red, purple, or brown pigments are frequently present on the dorsal surface, the ventral surface being usually unpigmented or very lightly so. Certain species, especially those that inhabit forest leaf mould, are deeply pigmented, some with striking patterns of contrasting colours, and these species are usually pigmented both dorsally and ventrally.

The body of the earthworm is divided into segments which are separated externally by intersegmental furrows that correspond to internal septae. Minute chaetae, or bristles, used in locomotion, occur on each segment except the first, each segment having 8, 10, 12, or more. Commencing on or in front of the fifteenth segment is the clitellum, a thick glandular portion of the epidermis, developed over a number of segments on sexually mature worms in the region of the male and female pores. Earthworms are hermaphroditic, both male and female organs being present, but they are not self-fertilising and, when mating takes place, sperm cells are exchanged. During oviposition the clitellum secretes a gelatinous sleeve-like structure, worked forward over the body, which receives ova as it passes the female pores and sperm cells as it passes the spermathecal pores. As the “sleeve” passes off the anterior end of the body, its ends are sealed and it becomes a cocoon.

Native earthworms feed almost entirely on dead and decaying remains of plants and, because of their limited capacity to move about, they are obliged to live very close to their sources of food. The presence of free water is essential for they have virtually no mechanism for conserving moisture. Respiration takes place by diffusion of gases through the moist body wall; hence both moisture and dissolved oxygen are essential. Earthworms are injured and may die by exposure to daylight, except when the intensity is very low, the more pigmented species being more resistant to light damage than the less pigmented. They are killed by temperatures in excess of 85°F–100F, but in most New Zealand habitats they escape the effects of extreme high or low temperatures by retreating to lower layers.

The pH tolerance varies from species to species but no native earthworms have been found in soils lower than pH4. Most earthworms are able to tolerate submersion in water and there are a few species that prefer an aquatic life. During heavy rains, however, earthworms are commonly driven to the surface, but this is most probably due to the shortage of oxygen in the water in their burrows.

The term “earthworm” cannot be satisfactorily defined in the scientific sense but it serves to describe a large number of species of the order Oligochaeta which inhabit soils and accumulations of decaying plant materials, and are occasionally found in shore and aquatic habitats. The earthworms of New Zealand consist of two groups of species. A large group of 173 native and five introduced species (27 genera) belong to the family Megascolecidae and a smaller group of 14 introduced species (seven genera) belong to the family Lumbricidae.

A very brief outline of the stages wool goes through from farm to woollen mill is useful:

(1) The sheep are mustered by shepherds with dogs and brought to (2) the sheep yards where they are “drafted” (sorted out) and those needing it (3) “dagged”, i.e., the pieces of dried dung are clipped off the wool round the tail. (4) They are held overnight in the shearing or woolshed to keep them dry. They also sweat, which makes (5) the shearing easier next day. (6) The shorn sheep are counted out (shearers are paid by the hundred shorn) and (7) returned to their paddocks. (8) The shorn fleece is picked up and expertly thrown out flat on a slatted wool table, where it is (9) skirted to remove wool not matching the main portion of the fleece. The fleece is then (10) rolled into a compact bundle. On some, mainly large sheep stations, it is now (11) classed by a specialist wool classer who places fleeces of similar type together into (12) the bins, where they are held until required for (13) pressing into bales by a manually operated press. The bales are now (14) stencilled with the owner's brand, bale number, and description of wool and (15) dispatched to the wool broker, who (16) records, weighs, and (17) stacks them. Some or all may be sent to other parts of the store for (18) reclassing, (19) binning, or (20) interlotting. A proportionate number of bales from each line are (21) displayed with ends opened on the well-lighted show floor. Here they are (22) valued by wool buyers, who subsequently (23) bid for them at auction. The wool is (24) pushed back into the bales, which are resewn and (25) check weighed. (26) Shipping marks are stencilled on them and they are (27) “dumped”, i.e., compressed to a smaller volume and secured with steel wires ready for (28) shipping. Wool may also go to local mills for domestic use, or to wool-scouring plants for further processing before export.

The steps outlined are typical for most of the wool – but the farmer may choose to ship his wool, either greasy or after scouring, direct to London for sale, or sell privately to a buyer in New Zealand. Freezing works also export much slipe wool from skins – about 200,000 bales per annum.

by John Pinkerton Erskine Duncan, M.AGR.SC. (1911–65), Chief Advisory Officer (Wool), Department of Agriculture, Wellington.

• Sheep (2 vols.), Stevens, P. G. (1958–61)

1835–1916: Wool and tallow, our only important pastoral products in the early days, were regularly shipped to Britain for sale and it was not until 1866 that the first wool auction sales were held locally. These quickly became popular, and soon British merchants were sending wool buyers to the New Zealand auctions. Other countries followed suit. Some of the big stations, however, continued to ship their wool to the London wool market, and a few still do this.

1916–20: Under a proclamation of 1916 the Crown became the sole buyer and seller of wool in New Zealand. During the remainder of the First World War, and up to 1920, Britain bought all New Zealand wool at a fixed price. This period is generally referred to as “the commandeer”.

1920–39: At the close of “the commandeer” Britain still held enormous stocks of unsold wool, including almost 800,000 bales from New Zealand. To prevent complete market chaos the British Australian Wool Realisation Association Ltd. (BAWRA) was set up and successfully disposed of the surplus between 1921 and 1924 without upsetting the market. Between the two world wars sheep numbers and wool production increased fairly steadily, though wool prices fell to ruinous levels of 3d. and 4d. a pound during the Depression.

1939–45: When war broke out in 1939 Britain once more offered to buy all New Zealand's wool for the duration of the war and one season thereafter. The average general price of the clip to be paid to the New Zealand grower was fixed at 12·25d. per pound and a team of appraisers was set up to value the many individual lines of wool. This was generally known as the “appraisement scheme”. A type and price schedule, known as the “Bareme”, was drawn up for all grades of wool: 977 individual types of greasy wool were listed with a “clean scoured” price for each. This was a tremendous task, as the general average price to the farmer for the 800,000 odd bales of greasy wool falling into these many different grades had to work out at 12·25d. per pound greasy. In 1942 the price was increased to 13·95d. per pound.

For many years New Zealand had eight selling centres for wool – Auckland, Napier, Wanganui, Wellington, Christchurch, Timaru, Dunedin, and Invercargill. During the appraisement scheme Tokomaru Bay, Tolaga Bay, Gisborne, Nelson, Blenheim, and Oamaru were added as appraisal centres. The seven wool clips from 1939–40 to 1945–46 were bought under this scheme.

1946–51: At the end of the war there was again an accumulation of more than 10 million bales of stockpiled wool in Britain, including 1¾ million bales from New Zealand. Once again a special organisation was set up to deal with it – this time called the “joint organisation”, usually called the “J.O.”. It set up minimum reserve prices for each grade of wool. Its main work was to sell stockpiled wool without disrupting the market, though it would also if necessary buy in new-clip wool when auction prices were below the reserve price. The New Zealand branch of “J.O.” became known as the New Zealand Wool Disposal Commission, and only once, in 1946–47, did it have to buy in much wool (nearly 108,000 bales, which it later resold at a profit). It was supposed to be a stabilising influence, but it did not have enough of the right kinds of stock wool in the right selling places to prevent the very high prices of 1948 to 1951. It successfully liquidated stocks and, its work done, was terminated in 1951. Growers provided half the operating costs of the “J.O.” scheme through a “contributory charge”.

1952 to the Present: It had been hoped to follow with a Commonwealth scheme for a reserve-price plan for wool – but Australia withdrew. Eventually New Zealand went ahead alone with its present “floor prices” plan, which was launched with the Wool Commission Act, from January 1952. The New Zealand Wool Commission must mainly ensure minimum or “floor” prices for New Zealand wool sold at auction. The Commission has not so far been severely tested by a long period of low prices which would force it to buy in a lot of wool at floor prices. Indeed, the reverse has been the case – prices have generally been well above the floor level and most of the relatively small amount of wool bought in has been resold later at a profit.

The capital funds of the Commission came originally from the Government's half share of the “J.O.” profits – about £20 million, plus the balance, about £6 million, remaining in the woolgrowers' contributory charge account. This capital has since been increased by interest on investments and profits on resale of wool. The Commission is not only self-supporting but also contributes money to the activities of the New Zealand Wool Board.

The figures given in the first column under “Quality Group” indicate the average fineness of the wool. In general, the higher the “count” or “quality number”, the finer the wool: 60s and upwards represents Merino wool, of which we produce only 2 per cent. A range in quality number (50/56s or 48/50s) indicates that the wool presented for sale is of mixed fineness. Counts 52s up to 58/60s represent half-bred and quarter-bred wools – showing varying proportions of Merino blood in the finer types: 20¼ per cent of wool sold at auction is of this class. The remaining 79 ½ per cent represents what the trade calls crossbred wool – a confusing term to the layman, for most of the wool comes from Romney sheep. (Besides fleece wool there are all the “oddments”, bellies, pieces, necks, crutchings, locks, lambs' wool, etc.) After every wool sale newspaper reports show a list of qualities and prices. The following table should be helpful in understanding these reports:

• Merino, 60/64s

• Extra-fine half-bred and Corriedale, 58s and 58/60s

• Fine half-bred and Corriedale, 56/58s

• Medium half-bred and Corriedale, 56s

• Extra-fine crossbred, 52s and 50/56s

• Fine crossbred, 50s

• Medium crossbred, 48/50s

• Crossbred, 46/50s

• Coarse crossbred, 46s and 46/48s

New Zealand runs a very large number of sheep for its size and produces over 600 million equivalent pounds of greasy wool a year. This includes shorn wool, slipe wool pulled from skins in the freezing works, scoured wool (which has been washed clean) and some wool on sheepskins: 97 per cent is exported to (mainly) Britain, France, and the United States of America. New Zealand ranks first in the world as a producer of crossbred wool, second to Australia as an exporter of wool, and third to Australia and the Soviet Union for total wool produced.

Different breeds of sheep grow different kinds of wool. The wool trade traditionally describes wool by its physical properties – fineness, length, tensile strength, colour, etc., rather than by the breed of sheep that grew it. The only dependable analysis of our clip is published annually by the New Zealand Wool Commission. The latest analysis gives this table:

Wool-producing farms can be roughly (and conveniently) divided into three groups: (i) High hill country (ii) Hill country (iii) Lowland.

1. High hill-country farms are mainly in the South Island. They are well up in the mountains, have low fertility, and therefore tend to be large. Nearly all run fine-wool sheep. Merinos are the only sheep which can stand up to the rigorous conditions in the higher parts. Lambing percentages are low, mortality can be very high in bad snowstorms, and almost the only source of income is wool. These farmers therefore pay much attention to the selection of their rams, as they have almost no scope for culling their flocks, and they take good care that their wool is well prepared for market. This is a highly specialised type of farming not closely related to the next two groups.

2. Hill-country farms are important because of their large total area and the surplus stock they supply to the lowland farms. Although conditions vary widely, farms of this sort would carry, on the average, between one and two sheep an acre. General fertility on these farms had for a long time been steadily declining until aerial topdressing halted or reversed the trend. Romneys and a small proportion of Romney-Cheviot cross are generally carried in the North Island, and mainly Corriedales, half-breds, and a few Merinos in the South. Rams are usually the only stock bought in. The products are wool (still the main income), some store lambs, a few fat wethers and store cattle, and an annual draft of cast-for-age ewes.

3. Lowland farms, also referred to as fattening farms, are a ready market for these old ewes which are mated with suitable rams for another season or two to produce fat lambs. Such farms are highly fertile and of high carrying capacity. The farmers usually buy in almost all their stock. They sell to the freezing works fat lambs (mostly milk fed off their mothers), fat ewes, and possibly some cattle. Wool used to be regarded as a by-product and received scant attention; but at present, with the price of lambs down by comparison, wool plays a bigger part in the returns.