Transcriber’s notes:
In this transcription, paired _underscores_ denote italicised text.
Archaic spellings such as ‘sedementary’ and ‘millepedes’ have not
been altered, and the following spelling inconsistencies have also
been left as in the original text: omnivorous/omnivorus,
eleagnus/elæagnus, silverfish/silver-fish, woodlice/wood-lice,
blowfly/blow-fly.
The following typographic errors have been corrected:
kindom —> kingdom
aphis lion —> aphis-lion
Jose —> José
ocurring —> occurring
necesary —> necessary
Crytolæmus —> Cryptolæmus
Crape —> Grape
pupuli —> populi
CAWTHRON INSTITUTE MONOGRAPHS
GARDEN PESTS
_in_
NEW ZEALAND
_A Popular Manual
for
Practical Gardeners, Farmers
and Schools_
By
DR. D. MILLER
Ph.D., M.Sc., F.R.S.N.Z., F.R.E.S.
Assistant Director and Chief Entomologist,
Cawthron Institute, Nelson
CONTENTS.
Page
Introduction 5
Chapter i.: General Review of the Animal Kingdom 7
Chapter ii.: Soil Organisms and Soil Fertility 12
Chapter iii.: Structure of Insects 17
Chapter iv.: Life Histories of Insects 22
Chapter v.: Sucking Insects 29
Chapter vi.: Sucking Insects (Concluded) 42
Chapter vii.: Leaf-feeding Insects 50
Chapter viii.: Boring and Underground Insects 61
Chapter ix.: Miscellaneous Pests 67
Chapter x.: Principles of Pest Control 74
Index 81
_Introduction_
This work deals with the insects and other animals having a detrimental
or beneficial influence upon horticulture in New Zealand. Its purpose
is to supply such general information as will enable the common animal
inhabitants of the garden to be identified and controlled, to act as a
popular guide for the use of practical gardeners and schools, and at
the same time serve as a source from which the examination requirements
set out in the syllabus of the New Zealand Institute of Horticulture
may be met.
As this work is for the benefit of the gardening public, and an
endeavour to diffuse some knowledge of certain natural problems, the
language of the scientist--which, unfortunately, tends to guard what
is known of these problems from the general reader--has been avoided
as much as possible; at times, however, this ideal cannot be adhered
to, but in such cases the reader should find no difficulty, and should
be prepared to become familiar, with the few terms used. To know the
scientific names of animals without being acquainted with the animals
themselves is a habit to be avoided, and is just about as instructive
as memorising the names of people in a town or telephone directory.
But animals must be named; though their popular names are used in
the following pages and as such names are very often misleading, the
scientific names are given in brackets in order to avoid confusion.
In such a work as this, illustrations are of great value, and these
are given wherever possible. One drawback to illustrations is that the
relative proportions of animals may be lost; for example, a microscopic
organism might require magnification by some 4,000 times its natural
size and so become equal to that of some of the most conspicuous
insects. Even with the best illustrations, however, it is essential
that the reader becomes familiar with the animals themselves. This
should present no difficulty to the reader, since he will find in his
garden all of the animals with which he is concerned--mostly insects
and their near relatives. Further, of very great assistance to him, he
will find the several excellent public museums throughout the country,
as well as the specialists at such research institutions as the
Cawthron Institute at Nelson.
To keep a work for the general reader in a readable form, the desire of
the author to cite the sources from which he derives his information
must be suppressed. If this were not done, the text would rapidly
become littered with endless references, much to the weariness and
confusion of the reader. Therefore, it should be remembered that a work
of this kind is a compilation from the publications of many scientists,
to which is added what little original information the writer himself
might possess.
Opportunity must be taken here to express one’s appreciation of the
assistance given by Mr. W. C. Davies and Mr. L. J. Dumbleton in the
preparation of the photographs and drawings, respectively.
CHAPTER I.
General Review of the Animal Kingdom.
At the outset it is advisable, by reviewing the animal kingdom as a
whole, to secure in perspective the relationships of the animals with
which the horticulturist has to deal.
To most people the animal kingdom is comprised chiefly of those animals
commonly met with in everyday life or in general reading--the game and
domestic animals and the fishes, all of which are similar in that they
possess a backbone or vertebral column, and are consequently known as
the vertebrates. Popularly, however, they are generally classed as the
“lower” and “higher” animals; there is certainly some accuracy in such
a haphazard classification, since, though all the vertebrates are,
strictly speaking, the “higher” animals, some are “lower” (_e.g._,
fish, frog, and bird) than others (_e.g._, kangaroo, dog, and man, the
highest of all).
But when it comes to the true “lower” animals, that vast assemblage
of less conspicuous creatures, the jelly-fish and corals, worms of
all kinds, sea-urchins, crayfish, wood-lice, spiders and insects,
shell-fish and snails, all characterised by the absence of a vertebral
column and known as the invertebrates, they are not collectively
visualised in a general sense as are the vertebrates. As a rule, these
invertebrates are known individually as independent units, except,
perhaps, in the case of worms, insects, spiders, wood-lice, etc., which
are very often collectively and haphazardly referred to as “insects,” a
term, in this sense, as ill-defined as it is unlimited.
That the average person should be more conversant with the vertebrates
than the invertebrates is, to a great extent, the natural outcome
of association and training; a possible influence is to be found at
the outset of one’s career in the many illustrated nursery books
depicting game and domestic animals, but seldom, if ever, any of
the invertebrates; and this impression tends to be further fostered
in later life by visits to the zoo, where we meet in person most of
the nursery book animals, and perhaps some of the lower forms, such
as insects; but the latter, in most cases, are there by chance, not
design, and against the will of the authorities.
In recent years, however, more public attention has been given to
the lower animals owing to the detrimental influence of many upon
agricultural development as well as upon public health. That such
animals are capable of ranking as fundamental factors hindering
human progress, may be realised when it is considered that, of the
invertebrates, insects alone comprise nearly four-fifths of the whole
animal kingdom! This has been graphically illustrated as follows by
F. E. Lutz, of the American Museum of Natural History:--Extend the arms
and fingers at right angles to the body, and let the distance from the
tip of the middle finger of one hand to that of the other represent
the number of different kinds of living animals; then the last joint
of the middle finger of the right hand will be proportionate to the
number of mammals (kangaroos, hoofed animals, rabbits, man, etc.), the
second joint to the reptiles and their relations, the first joint to
the birds, and the distance between the knuckles and the wrist to the
fishes. “In other words, you can hold the so-called zoological gardens
and their aquarium annexes in one hand.” Finally, the distance between
the wrist of the right arm and the tip of the middle finger of the left
will proportionately represent all the known species of invertebrates,
and of this section of the extended arms all except between a wrist and
an elbow will be insects.
The zoologist classifies the animals under twelve main divisions,
of which eleven contain the invertebrates and one the vertebrates;
these divisions are arranged in a series, the first containing the
simplest or lower animals, and the last the most complex or highest.
A glance at this classification will serve to give some idea of the
relative position in the animal kingdom of the animals which will be
dealt with in the following pages. The very lowest forms, belonging to
the first division, are micro-organisms known as the Protozoa; they
inhabit water and soil, and live upon their own kind or upon minute
plants, including bacteria, or are parasitic upon the higher animals,
some of these parasites causing such diseases as malaria. The Protozoa
are single units of living matter (protoplasm), and may be referred
to as the one-celled animals; they are mostly microscopic, and lead
an independent life, or are associated in colonies, but are capable,
as a rule, of carrying on independently all the functions of life,
though there are no organs such as those of digestion, respiration, and
circulation, as we know them in the higher animals. It is amongst such
simple forms that the distinction between the lowest animals and plants
ceases to be clear. As will be discussed later, there is evidence that
certain Protozoa have an important influence on soil fertility.
The remaining eleven divisions contain all other animals, ranging in
size from mere specks to the mass of the elephant; the bodies of these
are built up of a complex aggregate of countless cells of protoplasm
arranged in groups to form the organs of digestion, circulation,
respiration, reproduction, etc., each having its definite function
in the animals’ lives. The following are some typical or well-known
examples of each of these divisions, the technical names, with the
exception of the Protozoa, not being given:--
The Protozoa (reference should be made here to Fig. 1) are followed
by (2) sponges; (3) jelly-fish, sea-anemones, corals; (4) flat worms
(tape-worms, etc.); (5) round worms (thread-worms, eel-worms);
(6) sea-mats, lamp-shells; (7) wheel-animalcules; (8) star-fish,
sea-urchins; (9) segmented worms (earthworms); (10) crayfish, woodlice,
centipedes, millepedes, spiders, mites, insects; (11) shell-fish,
slugs, snails; (12) fish, frogs, lizards, birds, hedgehogs, rabbits,
man.
So far we have reviewed the animal kingdom from one aspect only--that
of classification, based on the resemblances and differences of the
individuals. It is now necessary to look at the subject from the
viewpoint of the horticulturist--that is, the relationships of the
animals to their surroundings, or environment, and to the welfare of
man. Of the two great life-groups--animals and plants--the plants are
of fundamental importance; without them no animal could exist, since,
of all living things, it is the green plants alone that are able to
convert the inorganic chemical constituents in soil, air and water
into living matter or protoplasm; and all animals, either directly or
indirectly, are dependent upon plants for their food supply. Plants,
therefore, may be looked upon as the primary producers of life, and
animals as the consumers. It is in this respect that the horticulturist
becomes interested, in that certain of these consumers destroy too many
of the plants grown by him for other purposes; fortunately, not all
of the consumers are destructive; many are of very great use to the
horticulturist and mankind in general.
The last point is well illustrated by the following classification
of the animal kingdom based upon the part it plays in human welfare;
this is a modification of the scheme adopted by the British Museum of
Natural History:--
_Group I._--Wild or domesticated animals used by man as beasts
of burden, source of food, or in the manufacture of various
products--_e.g._, sponges, crayfish, bees, silk-worms, shell-fish, and
various vertebrates, as fish, birds and mammals.
_Group II._--Animals detrimental to man’s welfare, attacking man
himself; animals and plants of value to him, or the products derived
therefrom--_e.g._, Protozoa, parasitic worms, mites, insects, and such
vertebrates as certain birds and mammals.
_Group III._--Animals aiding man’s welfare, as scavengers, or by
pollinating flowers, or by attacking and checking such animals as are
included in Group II.--_e.g._, Protozoa, parasitic worms, earthworms,
parasitic insects, spiders, and such vertebrates as certain birds and
mammals.
An analysis of the above classification shows that animals both aid and
hinder the progress of man, hence the use of the terms “beneficial”
and “destructive.” In nature, however, these terms are not altogether
applicable in the same sense, since the balance maintained between
animals and plants under natural conditions is an extremely fluctuating
one, though sufficient for natural purposes; with man, however, the
case is different. In order to compete in the world’s markets, and to
supply the growing demands of increasing population, a much higher
and dependable standard of productivity is required than is found in
nature. Consequently, whilst utilising, and increasing the efficiency
of the so-called natural enemies as auxiliaries in his fight against
destructive animals, man has found it necessary to develop an effective
system of artificial control, involving chemicals, resistant plants,
cultivation, crop rotation, etc., for the purpose of maintaining a more
stringent balance to meet his requirements.
Historical Review of New Zealand Conditions.
The animal population of European New Zealand is very different from
that of pre-European times, a position brought about naturally enough
by the changes resulting from agricultural development as practised in
the Old World, and the consequent creation of an environment foreign to
the country.
Though the official date of the settlement of New Zealand by Europeans
is 1840, the influences, inaugurating that upheaval of the natural
conditions which was later to have such a marked effect on the
economic development of the country, had commenced many years earlier.
[Illustration: Fig. 1.--Some common animals grouped to represent the
twelve main divisions of the animal kingdom.]
When the first Europeans set foot in New Zealand, they must have been
impressed by their unique surroundings, totally different from anything
to be met with in the Old World. They found the country dominated by a
forest quite unlike the forests of any other land, and inhabited by an
animal population presenting many unusual features. This terrestrial
population was characterised by an abundance of insects and spiders,
and a paucity of vertebrates excepting the birds; the vertebrates
consisted of a species or two of frogs, a few species of lizards, some
200 species of birds, and two species of bats, the last being the only
terrestrial mammals. In fact, the insects, spiders and birds were the
dominant animals, a feature common to other parts of the world, but the
scanty vertebrate population, other than birds, was a characteristic of
primeval New Zealand.
New Zealand being a country fitted for agriculture, settlement by
Europeans naturally resulted in extensive and rapid changes, since
the settlers brought with them the knowledge, implements, animals and
plants of the civilised world; and to make way for settlement, it was
necessary to remove the forests and drain the swamps, and to replace
them with cultivated crops and pastures. These activities have been so
thorough, that, within a period of some 90 years practically the whole
of the original North Island forests, and the greater part of those of
the South Island, have been cleared.
An outstanding feature of these changes is that many of the pests
associated with the agricultural animals and plants have been brought
to New Zealand with the animals and plants they infest, and these
exotic pests comprise by far the greater proportion of the destructive
animal population, there being but few native species forming the
balance. For example, 71 per cent. of the destructive insects are
exotic, and 29 per cent. native, while all the parasitic worms of
economic importance, all the destructive birds (_e.g._, sparrows) and
mammals (_e.g._, deer, wild pigs, and goats) are introduced.
The exotic factors that have set up this new environment may be
summarised as follows:--
(1) Clearing of the native vegetation.
(2) Introduced plants: _e.g._, grasses, forage crops, trees, etc.
(3) Introduced game animals: _e.g._, deer, pigs, rabbits, birds,
etc.
(4) Introduced destructive animals, infesting animals and plants of
economic value: _e.g._, parasitic worms, insects, etc.
(5) Animals imported to control pests, but which have become
destructive themselves: _e.g._, weasels, birds.