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Volume 67, 1938
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Observations on the Pollination of New Zealand Flowering Plants

[Read before Canterbury Philosophical Institute, October 2, 1935; received by the Editor, October 15, 1935; issued separtely, September, 1937.]

Introduction.

Seven years ago a paper on the pollination of New Zealand flowers was published by G. M. Thomson. In this he summarized the work that had already been done on this subject and commented on the extraordinarily few facts that had so far been recorded. In spite of his assertion of the urgent need for further investigations before the vegetation and insect life had undergone even greater changes, the study of the pollination of our native plants, however, does not appear to have attracted further attention. This is all the more surprising as the correlation between the flowers and insects in a country where both display such striking peculiarities should certainly be worth investigating, and might be of no little assistance in helping to elucidate some of the many biological problems to be found in New Zealand to-day.

The aim of this paper, therefore, is to record a few more observations which have been made on the pollination of New Zealand flowering-plants. In these investigations the aim has been to get a general view of the relationship between the plants and insects in New Zealand rather than to examine a few exceptional cases of flowers with peculiar pollinating contrivances, which have been to a large extent already described in other papers.

It is with great pleasure that I here acknowledge the research grant of the Royal Society of New Zealand, which enabled me to collect data from a wide area and observe plants in their natural habitat. I also wish to thank Miss E. A. Plank, Entomologist, of the Dominion Museum, for her kind assistance in identifying the various insects for me.

General Discussion.

Whether the peculiarity of our flora has been brought about by the peculiarity of our insect life, or vice versa, is a moot point; but in either case the perfect correlation between the one and the other is most striking.

The features that stand out most when New Zealand flowers are compared with those of the rest of the world are their lack of colour and size, as well as the fact that so many of them are unisexual; the bright reds, blues, and purples which render the flowers of other countries so attractive are here only occasionally met with, while most of our flowers are but puny specimens in comparison with those found in other parts of the world. When we turn to our native insects and compare them with those to be found elsewhere, we are again struck with certain peculiarities, which, though perhaps not

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so spectacular, are nevertheless most remarkable. Probably the most striking feature is the paucity of our insects; but of equal importance is the unusual proportion in which the various orders are to be found in New Zealand. According to Tillyard (1926) New Zealand possesses in proportion less than a third the number of Hymenoptera and more than twice the number of Diptera to be found anywhere else in the world. When these peculiarities of our insect life and of our flowers are considered, they are seen to elucidate each other. The various points will now be dealt with separately from a botanical point of view, showing how the flowers of New Zealand are particularly well adapted for pollination by the insects to be found here.

The Size of the Flowers.

Robertson (1927), who has investigated the flowers and insects of America for a great number of years, states that Mueller seems to have under-estimated the insect visitors of small flowers and the flowers visits of small insects. He says (1926) that flowers with exposed nectar admit the smaller insects. Such flowers are usually small. The larger the flowers the greater the number of unbidden guests. Homogamous flowers, which are so small that insects cannot obtain the nectar or collect the pollen without effecting pollination, seem to be best adapted to utilize all of the visitors which they attract.

In New Zealand, where insect visitors are scarce, it is not surprising, therefore, to find most of the flowers small in size. This will enable them to make use of all possible visitors; and often the lack of conspicuousness due to their minuteness is overcome by crowding them together in dense inflorescences. This, according to Robertson (1926), also enables flowers to make use of the lower insects of which our insect life is largely composed. He says, “The advantage to the plants of crowded flowers is probably in making the pollen and nectar more attractive by increasing a readily-obtained supply and in using the lower insects, 88 per cent. of whose visits are to social flowers.” The small flowers of New Zealand, therefore, are far more likely to be pollinated by our native insects than the large flowers of other countries, where the greater percentage of the flowers are adapted for pollination by long-tongued bees, which do not exist in New Zealand.

The Colour of Our New Zealand Flowers.

The lack of bright colours in our native flowers is probably the peculiarity that impresses itself most on people who visit New Zealand for the first time.

Thomson (1880), in his earliest paper on fertilization, states that he has consulted several authorities on this subject, amongst them Wallace (1876), who attributes the striking deficiency of gaily-coloured blossoms in New Zealand to the striking deficiency in the variety of insects. But this is not the case; it is due rather to the great predominance of Diptera and the total absence of long-tongued bees in New Zealand. In spite of the fact that at that time few

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flies had been observed to act as pollinators, Thomson very shrewdly suggests that Diptera will be found to be by far the most numerous class of flower-fertilizers. This is actually the case.

In correlating the unusual nature of our insects with the predominating colours of our flowers, we find that those colours predominate which attract the greatest percentage of our insects. Robertson (1926) states: “As we pass from red through yellow to white, the average number of visits increase. The visits of long-tongued bees, of bees in general, and Lepidoptera decrease, while the visits of flies, lower Hymenoptera and short-tongued bess increase.” This statement is amply borne out by the flowers in New Zealand, where white is the commonest colour of entomophilous flowers, and the reds, blues and purples are comparatively rare. In other countries the blue and purple flowers are in general constructed for long-tongued bees and Lepidoptera, of which the former are the more efficient as pollinators. In New Zealand red flowers are either large and adapted for bird-pollination or else small and adapted for short-tongued bees and flies, while the few blues and purples are also mostly adapted for short-tongued bees.

Yellow flowers are commoner in New Zealand than all the red, blue and purple flowers put together; these yellow flowers are mostly adapted for flies and short-tongued bees, although they are to a large extent visited by beetles; 30 per cent. of the flowers examined were found to have beetles on them, while 50 per cent. of them were visited by flies. In many cases the insects or beetles are probably of no great value to the flowers, but in quite a number of cases they were found to carry considerable quantities of pollen, and undoubtedly take a part in the cross-pollination of flowers.

Approximately 50 per cent. of the entomophilous flowers in New Zealand are white. This extraordinarily large percentage is explained by the insects found here. Grant Allen (1882) states: “The flowers which lay themselves out for fertilization by miscellaneous small flies are almost all white.” While Robertson (1928) says: “White, whether a simple or a specialized colour, usually belongs to short-tubed flowers adapted to short-tongued bees.” In New Zealand it has been found that white is the colour most attractive to the majority of New Zealand insects. It attracts a large number of native bees, more Lepidoptera than any other colour, besides a large number of beetles and flies.

It is interesting to note that many families, orders and genera, which in other parts of the world are typically bright-coloured and adapted for long-tongued bees, in New Zealand have white flowers with short tubes. Robertson (1928), after examining the flowers of America, makes the following statements: “Of 99 Gentiales, Personales, Lamiales, and Leguminosae, 59.5 per cent. are red. The majority are long-tongued bee flowers of which 70.7 per cent. are red. White seems to be a specialized colour, occurring in only 27.2 per cent. of the species. Of the short-tongued bee flowers, 64.2 per cent. are white.” A little earlier he states: “In general, red flowers have the deepest tubes, yellow flowers have intermediate, while white flowers have the shortest.” In New Zealand none of the Gentiales are red—all being either pure white or tinged with yellow or green;

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of the Personales 85 per cent. are either pure white or white faintly tinged with lilac, and 66 per cent. of the Lamiales are white. The Leguminosae show a greater percentage of colour, many of the Carmichaelias being tinged or streaked with purple; but, in spite of this, they are mostly adapted for short-tongued insects, 85 per cent. of them being less than ½in. long and many are as little as 1/10 in. long. So here the striking difference in our flowers from those of other countries may be attributed to the absence of long-tongued bees.

The large number of green flowers in New Zealand must also be mentioned. Thomson (1880) considers that New Zealand flowers are in a transition stage between entomophilous and anemophilous flowers. But this idea, that green flowers are flowers metamorphosed for wind-pollination, Robertson considers to be wrong. He says (1928) that he has examined green flowers and found a large number of insects sucking their nectaries. This statement is supported by the greenish-coloured flowers in New Zealand which are very effective in attracting insects, especially Diptera. Seventy per cent. of the flowers recently examined were found to be visited by flies. Most of these flowers were sweet-scented, a more effective lure for flies than bright colours, since in proportion these green flowers were visited by a greater number of Diptera than any other coloured flowers. It is interesting to note, too, that these green flowers were visited almost exclusively by flies, the other visitors being odd beetles. The efficiency of flies as pollinators cannot be doubted, as nearly all the ones examined carried large quantities of pollen on various parts of their bodies.

The Structure of the Flowers.

It has been mentioned above that most of the New Zealand flowers either attract all possible visitors, or if they are restricted to certain insects, these appear mostly to be short-tongued bees or Diptera. On examination the structure of the various flowers is seen to substantiate these facts.

Where in other countries we find numerous complicated devices to ensurc cross-pollination by long-tongued bees, these are comparatively rare in New Zealand. In most cases, the flowers are simple in structure with exposed pollen and nectar in a position where it can be easily reached by most insects, thus enabling cross-pollination to be carried out by a number of different insects. Where insects are so scarce we are not surprised to find that flowers are reduced to exposing their pollen and honey rather than hiding it in such a way that only the more highly-developed insects can reach it.

Where we find highly-specialized flowers, either these are adapted for birds, or, in the case of orchids, their wonderful construction does not seem to have the desired effect. Thomson (1927) states that of 80 Dendrobium Cunninghamii examined he found only 10 with the pollinia removed; and of 75 Prasophyllum Colensoi only 4 had their pollinia removed, while many of the Pterostylis species likewise did not seem capable of bringing about cross-pollination. He also states that in a number of orchids of various species he found self-fertilization taking place. Recent examination supports these facts.

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A number of Thelymitra longifolia and T. unifolia were watched and examined, yet, though the air was alive with insects, none were seen to approach the flowers, nor were any found with pollinia removed. The same was the case with Pterostylis Banksii. It therefore appears that the simpler structure mentioned above is more likely to ensure pollination by the insects in New Zealand.

This fact probably accounts for the prevalent so-called imperfection of our native flowers. Many species and genera which are hermaphrodite in other parts of the world are unisexual in New Zealand. It is by means of this unisexuality that our flowers can ensure cross-pollination taking place in spite of the comparatively simple structure due to the paucity of insects and large percentage of Diptera. Where in other countries flowers have highly complicated contrivances by means of which they can prevent self-fertilization taking place, in New Zealand this is not possible, as the chief insect visitors will only visit flowers which are short-tubed, with pollen and nectar within easy reach. To ensure cross-pollination the easiest and safest way is for the flowers to assume a unisexual habit, and this seems to have been brought about in an extraordinarily large number of cases in New Zealand, where unisexuality certainly need not be regarded as any sign of primitiveness.

Effect on the Degree of Hybridisation in New Zealand.

The large number of wild hybrids to be found in New Zealand is to some small extent explained when we consider the remarkable similarity and simplicity of the flowers and to what extent they attract all possible visitors. In flowers which are able either to protect their pollen or their pistil from a large number of insects the degree to which hybridization is possible will naturally be far smaller than in those which expose both their pollen and pistil to all visitors.

On examination, most of the genera containing hybrids will be found to have small flowers with the pistil and pollen well exposed and with no great difference in the structure of the flowers of the various species. In a genus such as Hebe, which seems to have an unlimited supply of hybrids, the flowers of the various species attract every type of insect—Diptera, Lepidoptera, Hymenoptera, and Coleoptera. All of these are frequent visitors, especially the first three orders, and all of these are capable of carrying quantities of pollen from one flower to another in such a manner as to effect crosspollination. With such ample opportunities it is no wonder that so many hybrids exist.

List of Insects.

The following is a list of the insects which have been caught actually in the flowers of the plants mentioned below. Their movements in the flowers were watched whenever possible, and their effect on the pollination of the flowers noted.

Order Thysanoptera.

Unidentified species have been found on the following:— Ranunculus Lyallii, Hoheria glabrata, Angelica montana, Hebe

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anomala, Hebe buxifolia, Hebe evenosa, Hebe speciosa, Hebe Lewisii, Hebe hulkeana, Melicytus ramiflorus, Myrtus bullata, Myoporum laetum, Pratia angulata, Olearia avicenniaefolia, Senecio eleagnifolius, Helichrysum glomeratum.

Order Hemiptera.

Immature Hemiptera on Helichrysum glomeratum, Olearia lacunosa.

Super-fam. Pentatomoidea (stink-bugs; shield-bugs). Immature specimens on Cotula coronopifolia, Epilobium glabellum, Ourisia macrophylla.

Fam. Lygaeidae (chinch-bugs). Hebe anomala, Olearia nummularifolia.

Nysius clavicornis on Ourisia macrophylla, Hebe buxifolia, Senecio perdicioides, Angelica rosaefolia, Olearia albida, Olearia arborescens, Olearia lacunosa.

Super-fam. Miroidea.

Fam. Miridae on Hebe albicans, Hebe anomola.

Stenotus binotatus on Hebe hulkeana, Hebe anomola.

Sub-order Homoptera.

Fam. Cercopidae.

Philaenus trimaculatus on Melicytus ramiflorus, Carmichaelia flagelliformis.

Super-fam. Fulgoridea. Fam. Cixiidae.

Koroana arthuria on Gaultheria rupestris.

Super-fam. Psylloidea. Fam. Psyllidae.

Rhinocola sp. on Corokia cotoneaster.

Fam. Aphididae on Senecio remotifolius.

Order Coleoptera. Sub-order Polyphaga.

Super-fam. Hydrophiloidea. Fam. Hydrophilidae.

Rygmodus modestus on Rubus australis. Hebe salicifolia, Euphrasia cuneata.

Super-fam. Colydioidea. Fam. Coccinellidae.

Coccinella tasmani on Ranunculus acaulis.

Cryptophagus sp. Melicytus ramiflorus.

Telmatophilus nitens on Ranunculus acaulis. Fam. Cryptophagidae.

Super-fam. Lampyroidea. Fam. Melyridae.

Dasytes sp. on Euphrasia cuneata, Leptospermum scoparium, Dracophyllum acicularifolium, Olearia arborescens, Aciphylla squarrosa.

Dasytes minuta on Melicytus ramiflorus, Helichrysum glomeratum.

Dasytes anacharis on Hebe speciosa X Lewisii.

Super-fam. Dascilloridea. Fam. Dascillidae.

Nesocyphon marmoratus on Aciphylla squarrosa, Leucogenes leontopodium.

Cyphon sp. on Senecio eleagnifolius, Olearia lacunosa.

Super-fam. Scarabaeoidea. Fam. Scarabaeidae.

Pyronata festiva on Leptospermum scoparium.

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Super-fam. Cerambycoidea. Fam. Cerambycidae.

Navomorpha sulcatum on Hebe speciosa X Lewisii. Fam. Chrysomelidae.

Luperus. sp. on Gaultheria rupestris, Phormium Colensoi, Celmisia spectabilis, Aciphylla squarrosa.

Luperus vulgaris on Brachyglottis repanda.

Super-fam. Curculionoidea.

Fam. Curculionidae (weevils) on Rubus australis, Coriaria aborea, Aristotelia racemosa, Ranunculus Lyallii, Olearia sp.

Stephanorhynchus tarsalis on Hebe salicifolia.

Eugnomus sp. on Ourisia macrophylla.

Eugnomus dennanensis on Senecio eleagnifolius.

Platyomida caudata on Dracophyllum rosmarinifolium, Aciphylla Colensoi.

Sargon hudsoni on Aciphylla Colensoi.

Scolopterus penicillatus on Helichrysum glomeratum.

Scolopterus tetracanthus on Schefflera digitata.

Oreocharis sp. on Ourisia macrophylla.

Unnamed species of Coleoptera on Aciphylla squarrosa, Melicytus ramiflorus, Leucogenes leontopodium, Geniostoma ligustrifolium, Senecio remotifolius, Senecio eleagnifolius, Angelica rosaefolià, Helichrysum glomeratum, Olearia arborescens, Olearia lacunosa, Pratia angulata, Ranunculus Lyallii, Angelica montana, Myoporum laetum, and Carmichaelia sp.

Order Neuroptera.

Dragon-fly on Euphrasia cuneata.

Order Hymenoptera.

Super-fam. Ichneumonidea.

Fam. Ichneumonidae on Veronica Bidwilli, Melicytus ramiflorus.

Fam Braconidae on Melicytus ramiflorus, Muehlenbeckia complexa, Celmisia coriacea.

Super-fam. Chalcidoidea on Helichrysum glomeratum.

Super-fam. Formicoidea on Ranunculus Lyallii, Angelica montana, Apium prostratum, Ranunculus acaulis.

Super-fam. Apoidea. Fam. Colletidae.

Paracolletes sp. on Hebe albicans, Hebe Barkeri, Hebe buxifolià, Hebe speciosa X Lewisii, Olearia furfuracea.

Paracolletes hirtipes on Hebe speciosa, Hebe Lewisii.

Fam. Andrenidae.

Halictus sordidus on Hebe anomola, Hebe buxifolia, Hebe angustifolia, Hebe speciosa X Lewisii, Ourisia macrophylla, Olearia nummularifolia.

Halictus familiaris on Libertia ixioides.

Fam. Hylaeidae.

Hylaeus capitosus on Metrosideros robusta, Metrosideros tomentosa, Hebe speciosa, Gentiana patula, Olearia lacunosa.

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Fam. Apidae.

Apis mellifera on Myosotidium Chathamica, Astelia Solandri, Gentiana patula.

Bees, species unknown, on Astelia solandri, Metrosideros robusta, Metrosideros lucida, Hebe speciosa X Lewisii, and various Hebe hybrids, Myoporum laetum.

Order Diptera.

Super-fam. Tipuloidea.

Fam. Tipulidae on Corokia cotoneaster.

Super-fam. Bibionoidea. Fam. Bibionidae.

Dilophus sequis on Angelica rosaefolia, Olearia arborescens.

Dilophus nigrostigma on Clematis Colensoi, Leptospermum scoparium var. incanum, Myoporum laetum, Muehlenbeckia complexa, Hymenanthera crassifolia, Hebe hulkeana, Olearia arborescens, Celmisia Lindsayi.

Super-fam. Culicoidea. Fam. Chiromidae.

Tanypus malus on Dodonea viscosa.

Super-fam. Tabanoidea. Fam. Tabanidae.

Silvius maorium on Hebe salicifolia.

Fam. Stratiomyiidae.

Odontomyia chloris on Parsonsia capsularis.

Odontomyia atrovirens on Hebe hulkeana, Hebe salicifolia.

Odontomyia fulviceps on Hebe salicifolia.

Actina opposita on Aciphylla squarrosa.

Super-fam. Asiloidea. Fam. Therevidae.

Anabarrhynchus castaneus on Angelica rosaefolia.

Super-fam. Asiloidea. Fam. Asilidae.

Itamus bulbus on Hebe speciosa X H. Lewisii.

Saropogon fugiens on Hebe hulkeana.

Super-fam. Empidoidea. Fam. Empididae.

Hilarempis niger on Olearia arborescens.

Super-fam. Syrphoidea.

Fam. Syrphidae on Celmisia coriacea.

Helophilus hochstetteri on Myoporum laetum, Veronica decumbens, Angelica rosaefolia, Olearia arborescens.

Syrphus novae-zealandiae on Pittosporum crassifolium, Hebe speciosa X Lewisii, Gentiostoma ligustrifolium, Hebe salicifolia, Senecio remotifolius, Gaultheria rupestris, Angelica rosaefolia, Celmisia prorepens, Celmisia coriacea, Aciphylla squarrosa, Metrosideros robusta, Leptospermum scoparium.

Melanostoma sp. on Olearia avicenniaefolia.

Melanostoma apertum on Ranunculus Lyallii.

Platycheirus clarkii on Ourisia macrophylla.

Super-fam. Eristalimae.

Helophilus antipodus on Hebe parviflora.

Super-fam. Muscoidea. Section Acalyptrata.

Fam. Sciomyzidae.

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Limnia sp. on Aciphylla Colensoi.

Fam. Opomyzidae on Pittosporum crassifolium, Olearia avicennniaefolia.

Section Calyptrata.

Fam. Anthomyiidae on Hebe macrocarpa, Angelica rosaefolia.

Trichophthicus melus on Melicytus ramiflorus, Angelica rosaefolia.

Fam. Muscidae.

Musca domestica on Metrosideros robusta, Senecio Greyii.

Calliphora stygia on Pittosporum crassifolium, Leptospermum scoparium.

Calliphora erythrocephala on Metrosideros robusta, Olearia avicenniaefolia.

Calliphora quadrimaculata on Rhopalostylis sapida, Schefflera digitata, Angelica rosaefolia.

Lucillia caesar on Aciphylla squarrosa

Anastellorhina stygia on Hebe speciosa.

Fam. Tachinidae.

Macquartia sp. on Hebe Lewisii.

Hystricia pachyprocta on Seneco remotifolius, Olearia arborescens, Leptospermum scoparium, Angelica rosaefolia, Hebe speciosa X Lewisii, Dodonea viscosa.

Unknown Tachinidae on Olearia nummularifolia, Pittosporum crassifolium, Pittosporum tenuifolium, Dodonea viscosa, Rubus australis, Angelica rosaefolia, Leptospermum scoparium, Griselinia littoralis.

Protohystrichia signata on Hebe salicifolia.

Unknown flies on Hoheria glabrata, Gentiana patula, Leptospermum scoparium, Gaultheria rupestris, Olearia Colensoi, O. avicenniaefolia X moschata, Olearia arborescens, Olearia furfuraceae, Olearia lacunosa, Geniostoma ligustrifolium, Melicytus ramiflorus, Helichrysum glomeratum, Pratia angulata, Ranuculus Lyallii, Hebe subalpina, Senecio Greyii, Senecio eleagnifolium, Senecio lautus, Metrosideros robusta, Tillaea siberiana, Myoporum laetum, Muehlenbeckia complexa, Schefflera digitata, Metrosideros lucida, Parsonsia capsularis.

Order Lepidoptera.

Super-fam. Pyraloidea. Fam. Pyraustidae.

Scoparia sp. on Aciphylla Colensoi.

Super-fam. Noctuoidea. Fam. Hypsidae.

Nyctemera annulata on Senecio remotifolius.

Super-fam. Notodontoidea. Fam. Sphingidae.

Hopliocnema cyanea on Helichrysum glomeratum, Ourisia macrophylla, Senecio latifolius. Fam. Larentiidae.

Hopliocnema hookeri on Angelica rosaefolia.

Xanthorhoe aegrota on Aciphylla Colensoi.

Notoreas sp. on Gentiana patula.

Super-fam. Nymphaloidea. Fam. Nymphalidae.

Pyrameis gonerilla on Hebe albicans.

Fam. Lycaenidae.

Chrysophanus feredaye on Hebe salicifolia.

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Chrysophanus sallustius on Hebe salicifolia, Muehlenbeckia complexa, Celmisia prorepens, Hebe hulkeana, Hebe subalpina.

Moths (unnamed) on Pratia angulata, Angelica montana, Metrosideros robusta, Parsonsia capsularis.

List of Plants Observed.

The following is a list of the plants which were observed wherever possible in their natural habitat. The insects found on the flowers were collected without discrimination and all were examined for any pollen they might be carrying. The pollen found on them was also examined to see whether it was obtained from the flower on which the insect was collected orfrom some other flower.

Palmae.

Rhopalostylis sapida: Calliphora quadrimaculata and numerous other small and large flies not identified.

Liliaceae.

Cordyline australis: Numerous Diptera not identified.

Astelia Solandri: Numerous large Diptera. Numerous bees, amongst them the introduced Apis mellifera.

Phormium Colensoi: Beetles belonging to the genus Luperus.

Iridaceae.

Libertia ixioides: Halictus familiaris, a burrowing bee.

Orchidaceae.

Microtis unifolia: A small spider.

Pterostylis Banksii: A spider. A number of other species (Dendrobium Cunninghamii, Earina suaveolens, Thelymitra longifolia, Thelymitra uniflora, Corysanthes rotundifolia, and Gastrodia Cunninghamii) were also examined, but no insect visitors were observed.

Polygonaceae.

Muehlenbeckia complexa: Dilophus nigrostigmata, fam. Bibionidae, numerous, as well as a number of other flies not identified. Chrysophanus sallustius, a butterfly.

Ranunculaceae.

Clematis Colensoi: Dilophus nigrostigmata, flies, numerous.

Clematis indivisa: Numerous large flies and introduced bees, not identified.

Ranunculus Lyallii: Melanostoma apertum as well as numerous other Diptera, weevils and thrips.

Ranunculus acaulis: Telmatophilus nitens, a beettle, and a number of ants.

Crassulaceae.

Tillaea Siberiana: Numerous flies not identified.

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Pittosporaceae.

Pittosporum crassifolium: Numerous flies, Calliphora stygia, Syrphus novae-zealandiae, and members of the fam. Tachinidae, and the fam. Opomyzidae were common; also the introduced bee Apis mellifera.

Pittosporum tenuifolium: Numerous Diptera belonging to the family Tachinidae.

Rosaceae.

Rubus australis: Rygmodus modestus, a beetle, and flies belonging to the family Tachinidae were common; also a number of weevils and thirps.

Leguminosae.

Carmichaelia flagelliformis: Philaenus trimaculatus, fam. Cercopidae.

A common frog-hopper, and some beetles not identified.

Carmichaelia odorata: Numerous small native bees not identified.

Clianthus puniceus: A number of bumble-bees.

Corynocarpaceae.

Corynocarpus laevigata: Numerous flies not identified.

Sapindaceae.

Dodonea viscosa: Hystricia pachyprocta, flies belonging to the Tachinidae and other small flies were numerous. Also Tanypus malus, a midge.

Rhamnaceae.

Pomaderris elliptica: Hover flies.

Discaria toumatou: Numerous Diptera not identified.

Elaeocarpaceae.

Aristotelia racemosa: Numerous weevils not identified.

Malvaceae.

Hoheria populnea: Numerous Diptera not identified, also Thysanoptera.

Hoheria sexstylosa: Numerous Diptera and Hymenoptera not identified.

Violaceae.

Melicytus ramiflorus: Trichophthicus melus, fam. Anthomyiidae, cannibal flies and Ichneumonidae numerous; also Philaenus trimaculatis, fam. Cercopidae, a frog-hopper. Braconidae, Dasytes minuta, fam. Melyridae, and Cryptophagus sp., fam. Cryptophagidae, beetles numerous, as well as a number of Thysanoptera.

Hymenanthera crassifolia: Dilophus nigrostigma, fam. Bibionidae, and Xenocalliphora hortense, fam. Calliphorinae, flies, numerous.

Myrtaceae.

Leptospermum scoparium: Pyronota festiva, fam. Scarabaeidae, the Manuka beetle, beetles belonging to the Dasytes sp., fam. Melyridae. Small flies, Dilophus nigrostigma, fam. Bibionidae,

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Calliphora stygia, fam. Calliphorinae, the Australian blow-fly, Hystricia pachyprocta, fam. Tachinidae, and other Tachinidae besides Syrphus novae-zealandiae, fam. Syrphidae, hover-flies all numerous.

Metrosideros lucida: Small native bees and numerous Diptera, among them hover-flies and blue-bottles not identified.

Metrosideros tomentosa: Hylaeus capitosus, fam. Hylaeidae, bees.

Metrosideros robusta: Hylaeus capitosus, fam. Hylaeidae, bees most numerous. Also a number of Diptera. Musca domestica, fam. Muscidae, Calliphora erythrocephala, and Syrphus novaezealandiae, fam. Syrphidae.

Onagraceae.

Epilobium glabellum: Immature insect belonging to fam. Pentatomidae.

Araliaceae.

Schefflera digitata: Numerous Diptera, Calliphora quadrimaculatus, fam. Calliphorinae and Xenocalliphora hortense, fam. Calliphorinae. Also a weevil, Scolopterus tetracanthus.

Nothopanax arboreum: Numerous Diptera not identified.

Umbelliferae.

Aciphylla Colensoi: Flies, belonging to Limnia sp., fam. Sciomyzidae. A moth, Xanthorhoe aegrota, fam. Larentiidae, and Scoparia sp. and several weevils. Platyomida caudata, fam. Curculionidae, and Sargon hudsoni, fam. Curculionidae.

Aciphylla squarrosa: Numerous Diptera—Actina opposita, fam. Stratiomyiidae, Lucilia caesar, fam. Muscidae, and Syrphus novae-zealandiae, and a number of beetles, Nesocyphon marmoratus, fam. Dascillidae, Dasytes sp., fam. Melyridae, Luperus sp., fam. Chrysomelidae.

Anisotome dissectum: Numerous Diptera not identified.

Angelica montana: Several flies and moths and a number of beetles not identified, also thrips.

Angelica rosaefolia: Numerous flies, Calliphora quadrimaculatus, fam. Muscidae, Dilophus sequis, fam. Bibionidae, Trichophthicus melus, fam. Anthomyiidae, flies belonging to the Tachinidae and Anthomyiidae, Helophilus hochstetteri, fam. Syrphidae, Syrphus novae-zealandiae, fam. Syrphidae, Anabarrhynchus castaneus, fam. Therevidae, Hystricia pachyprocta, fam. Tachinidae, as well as a number of unidentified flies. Also beetles, Hopliocnema hookeri, fam. Curculionidae, and a plant-bug Nysius clavicornis, fam. Lygaeidae.

Cornaceae.

Corokia cotoneaster: Rhinocola sp., fam. Psyllidae, a plant-louse and a daddy-long-legs, fam. Tipulidae.

Griselinia littoralis: Numerous small Diptera not identified.

Ericaceae.

Gaultheria rupestris: Syrphus novae-zealandiae and other flies. Beetles, Luperus sp., fam. Chrysomelidae, and Koroana arthuria, fam. Cixiidae, a leaf-hopper.

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Epacridaceae.

Dracophyllum acicularifolium: Beetles, Dasytes sp., fam. Melysidae.

Dracophyllum rosmarinifolium: Platyomidae caudata, fam. Curculionidae, beetles.

Loganiaceae.

Geniostoma ligustrifolium: Syrphus novae-zealandiae, fam. Syrphidae, and numerous other flies as well as Rygmodus modestus, fam. Hydrophilidae, a beetle.

Gentianaceae.

Gentiana patula: Apis mellifera, fam. Apidae, and numerous native bees, Hylaeus sp., fam. Hylaeidae. As well as unidentified flies, beetles, and a moth Notoreas sp., fam. Hydriomenidae.

Apocynaceae.

Parsonsia heterophylla: Numerous flies, Odontomyia chloris, fam. Stratiomyiidae, Hystricia pachyprocta, fam. Tachinidae, and hover-flies, also a beetle Luperus vulgaris, fam. Chrysomelidae, and several moths, of which one belongs to Scoparia sp., fam. Pyraustidae.

Boraginaceae.

Myosotidium Chathamica: Apis mellifica, fam. Apidae.

Scrophulariaceae.

Hebe speciosa: Hylaeus capitosus, fam. Hylaeidae, and Paracolletes hirtipes, fam. Colletidae, bees and flies Anastellorhina stygia, fam. Muscidae and thrips.

Hebe speciosa X Lewisii: Numerous flies, Hystricia pachyprocta, fam. Tachinidae, Itamus bulbus, fam. Asilidae and Syrphus novae-zealandiae, fam. Syrphidae. Also bees, Paracolletes sp., fam. Colletidae, Halictus sordidus, fam. Andrenidae, and beetles Dasytes anacharis, fam. Melyridae and Navomorpha sulcatum, fam. Cerambycidae.

Hebe Barkeri: Numerous bees, Paracolletes sp., fam. Colletidae.

Hebe salicifolia: Numerous bees, Halictus sordidus, fam. Andrenidae and Paracolletes hirtipes, fam. Colletidae, butterflies, Chrysophanus feredaye, fam. Lycaenidae, and Pyrameis gonerilla, fam. Nymphalidae, a beetle Nysius clavicornis, fam. Lygaeidae, and Diptera, Protohystrichia signata.

Hebe macrocarpa var. talisepae: A fly belonging to the Anthomyiidae.

Hebe angustifolia: Numerous bees Halictus sordidus, fam. Andrenidae.

Hebe parviflora: Diptera, Helophilus antipodes, fam. Syrphidae.

Hebe Lewisii: Nyctemera annulata, fam. Arctiidae, a moth, Paracolletes hirtipes, fam. Colletidae, bees and numerous flies of Macquartia sp., fam. Tachinidae, also a number of thrips and unidentified butterfly.

Hebe evenosa: Pyrameis gonerilla, fam. Nymphalidae, the red admiral butterfly and thrips.

Hebe subalpina: Numerous unidentified Diptera and Chrysophanus sallustius, fam. Lycaenidae, a butterfly.

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Hebe buxifolia: Numerous bees, Halictus sordidus, fam. Andrenidae, and Paracolletes hirtipes, fam. Colletidae. Also Pyrameis gonerilla, fam. Nymphalidae, a butterfly and a weevil Nysius clavicornis, fam. Lygaeidae, and numerous thrips.

Hebe anomola: Numerous bees, Halictus sordidus, fam. Andrenidae, a number of unidentified flies, thrips and plant-bugs Stenotus binotatus, fam. Miridae, thrips.

Hebe decumbens: Helophilus hochstetteri, fam. Syrphidae.

Hebe albicans: Numerous bees of Paracolletes sp., fam. Colletidae, butterfly Pyrameis gonerilla, fam. Nymphalidae and Hemiptera belonging to the fam. Miridae.

Hebe hulkeana: Numerous Diptera, Odontomyia atrovirens, fam. Stratiomyiidae, Dilophus nigrostigmata, fam. Bibionidae, and Saropogon fugiens, fam. Asilidae, a butterfly Chrysophanus sallustius, fam. Lycaenidae, plant-bugs, Stenotus binotatus, fam. Miridae and numerous thrips.

Veronica Bidwillii: Hymenoptera belonging to the Ichneumonidae.

Ourisia macrophylla: Numerous bees, Halictus sordidus, fam.

Andrenidae. Numerous bees, Diptera, Platycheirus clarkei, fam.

Syrphidae and numerous weevils of Eugonomus sp., Hopliocnema cyanea, fam. Sphingidae, and of Oreocharis sp., fam. Curculionidae.

Euphrasia cuneata: Numerous beetles, Rygmodus modestus, fam. Hydrophilidae, Dasytes sp., fam. Melysidae.

Myoporaceae.

Myoporum laetum: Numerous flies and moths, also a few bees and beetles not identified, also thrips.

Campanulaceae.

Pratia angulata: Numerous unidentified flies and Coccinilla tasmanii, fam. Coccinellidae, a beetle, also some small moths.

Compositae.

Olearia Colensoi: Unidentified Diptera.

Olearia furfuraceae: Bees belonging to Paracolletes sp., fam. Colletidae.

Olearia lacunosa: Numerous small beetles, Cyphon sp., fam. Dascillidae. Numerous bees Hylaeus capitosus, fam. Hylaeidae, and Nysius sp., fam. Lygaeidae, plant-bugs.

Olearia albida: Nysius clavicornis, fam. Lygaeidae, a weevil.

Olearia nummularifolia: Diptera belonging to family Tachinidae.

Olearia arborescens: Diptera, Dilophus nigrostigma and Dilophus sequis, fam. Bibionidae, Helophilus hochstetteri, fam. Syrphidae, Hystricia pachyprocta, fam. Tachinidae, Hilarempis niger, fam. Empididae. Also beetles, Dasytes sp., fam. Melycidae and a weevil Nysius clavicornis, fam. Lygaeidae.

Olearia avicenniaefolia: Calliphora erythrocephala, fam. Muscidae, Melanostoma sp., fam. Syrphidae and other flies belonging to the fam. Opomyzidae. Also thrips.

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Clemisia prorepens: Syrphus novae-zealandiae, fam. Syrphidae. A hover-fly and a butterfly Chrysophanus sallustius.

Celmisia spectabilis: A beetle, Luperus sp., fam. Chrysomelidae.

Celmisia coriacea: Numerous Diptera belonging to the Stratiomyiidae and the Brachonidae. Also Syrphus novae-zealandiae.

Leucogenes leontipodium: Nesocyphon marmoratus, fam. Dascillidae and other beetles; also unidentified Diptera.

Helichrysum glomeratum: Unidentified Diptera, a small moth Hopliocnema cyanea, fam. Sphingidae, an immature Hemiptera and several wasps belonging to the Chalcidoidea. Also beetles, Dasytes minuta, fam. Melyridae and Scolopterus penicillatus, fam. Curculionidae, and thrips.

Cotula coronopifolia: Immature insects belonging to the family Pentatomidae.

Brachyglottis repanda: Luperus vulgaris, fam. Chrysomelidae; numerous beetles.

Senecio lautus: Numerous unidentified small flies.

Senecio latifolius: Hopliocnema cyanea; a plant-bug.

Senecio perdicioides: Small weevils, Nysius clavicornis, fam. Lygaeidae.

Senecio Greyii: Musca domestica, fam. Muscidae, a fly.

Senecio remotifolius: Numerous flies, Hystricia pachyprocta, fam.

Tachinidae and Syrphus novae-zealandiae, fam. Syrphidae. Also a moth Nyctemera annulata, fam. Hypsidae.

Senecio eleagnifolius: Numerous beetles belonging to Cyphon sp., fam. Dascillidae, and weevils, Eugnomus dennanensis, fam. Curculionidae. Also numerous unidentified flies and thrips.

Summary.

The object of this paper is to show the correlation which exists between the flowers and insects of New Zealand, and to what extent the peculiar insect fauna has affected the flora of New Zealand.

1.

The lack of colour, small size and unisexuality of the New Zealand flowers, and the unusual proportion of insect families and comparative scarcity of insects in New Zealand are discussed.

2.

The prevalence of small flowers and their social grouping is considered to be due to the scarcity of insect life.

3.

The colour of New Zealand flowers is considered. The lack of reds, blues and purples is due to the absence of native long-tongued bees, while the yellow and white flowers are best adapted for pollination by short-tongued bees and flies which are the chief pollinators in New Zealand. The comparatively large percentage of green flowers is due to the fact that Diptera predominate.

4.

The adaptation of New Zealand flowers to pollination by short-tongued bees and flies has led to a predominance of short tubes and exposed pollen and pistil, which in its turn results in reversion to unisexual flowers to avoid self-pollination.

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5.

The similarity and simplicity in the structure of the flowers and the great extent to which cross-pollination is brought about by a variety of insects may be regarded as one of the causes of the large number of wild hybrids in New Zealand.

References.

Allen, G., 1882. The Colours of Flowers, Macmillan & Co., London.

Robertson, C., 1924. Flowers and Insects, XXIII, Bot. Gaz., vol. 78, pp. 68–83.

—— 1927. Flowers and Insects, XXIV, Ecology, vol. VIII, no. 1, pp. 113–132.

—— 1928. Flowers and Insects, XXIV, Ecology, vol. IX, no. 7, pp. 505–526.

Thomson, G. M., 1880. On the Fertilization of New Zealand Flowering Plants, Trans. N.Z. Inst., vol. XIII, pp. 271–288.

—— 1927. The Pollination of New Zealand Flowers by Birds and Insects, Trans. N.Z. Inst., vol. 57, pp. 106–125.

Tillyard, R. J., 1926. The Insects of Australia and New Zealand, Angus and Robertson, Australia.

Wallace, A. R., 1876. The Geographical Distribution of Animals, vol. 1, p. 457, Macmillan & Co., London.