Principles of Pest Control.
In dealing with the control of plant pests, the objective is to prevent
attacks, or, when the attacks have established, to check them as much
as possible. In the latter case the term “exterminate” is in too
frequent use; it is not usually practicable to exterminate a pest, and
the best that can be done is to check or control it.
In the control of animal pests, it should be borne in mind that the
pests are usually associated with other factors inimical to plant life,
such as unthrifty plants, due to injury or malnutrition, and fungous
and bacterial diseases, any one of which might be either the primary or
secondary cause of plant injury.
Though at times one method may serve as a means of control, generally
it is a combination of methods that gives the most satisfactory
results, rendering the conditions favourable for the plant and
unfavourable for the pests and diseases. The principles underlying
control are:--
(_a_) Garden management.
(_b_) Use of chemicals.
(_c_) Influence of natural enemies.
(a) Garden Management.
All parts of plants, both above and below ground, are subject to
infestation by pests and diseases. Under garden conditions, cultivation
is intensive, and plants are grown year after year on the same ground
in surroundings much more sheltered and crowded than in the open field.
Sound garden management is therefore an important control factor, and
the following features are fundamental:--
CONDITION OF SOIL.--The vigour of plants is dependent on the soil,
which therefore must be kept in the right state; it must be well
tilled, and must contain the requisite nourishment and moisture
available for plant use, and as far as possible be free of an abnormal
population of root feeding pests, such as eelworms and the larvæ of
many insects. Proper cultivation is therefore the important factor in
bringing the soil into the state most favourable to plant life, as all
inimical factors, including pests, are reduced. Wherever practicable,
as in glass-houses, soil-inhabiting pests and diseases can be
completely controlled by steam sterilisation.
IMPORTATION OF PESTS.--One of the readiest methods of infesting a
garden is the importation of pests on plants, and every care should
be taken to secure only pest-free stock. In this respect, also, must
be mentioned the use of stable and barnyard manure, in which pests
such as insect larvæ, woodlice and eelworms are introduced; artificial
fertilisers are therefore safer.
OVERCROWDING.--The tendency to overcrowd, especially in household
gardens, is to be avoided; a favourite habit is to plant something
in every available space. Under such conditions pests and diseases
will abound, and before attempting to spread over a large area, and
so lessen the effect of their depredations, they concentrate in mass
formation within the confines of the garden as long as the food supply
lasts; further, plants tend to be less vigorous and more susceptible to
infestation under crowded than under more open conditions.
INJURY TO PLANTS.--Care should be taken not to injure plants with
garden tools during cultivation, and a clean cut should always be the
object in pruning. Mechanical injury opens the way for infestation by
diseases and some insects.
GARDEN SANITATION.--Clean gardening is an extremely important control
factor. In most gardens there are rank growths of grass and weeds in
out-of-the-way places, along boundaries, and bordering cultivated
plots. Such growths, especially when the weeds are related to the
garden plants, are always favourite breeding places for many pests that
move on to cultivated plants immediately they appear above ground.
If these growths are cut and burned in the winter, and the ground
thoroughly dug, many a spring infestation will be suppressed by the
control of hibernating pests; it is the control of spring infestations
that will save a great deal of trouble throughout the summer and autumn.
The compost heap, where garden refuse is dumped until sufficiently
rotted, may be a source of infestation; not only does it attract and
breed many destructive underground pests, but it may be infested with
the spores of diseases harboured by the plant refuse of which it is
composed; it is thus a ready means of reinfesting the soil. Diseased
and pest-infested refuse should be burned without delay, and only
healthy refuse used for the compost heap if not dug into the ground,
where it will rot.
CROP ROTATION.--Growing the one type of crop on the same piece of
ground for several seasons encourages the development of pests and
diseases; but by a rotation of different kinds of plants the continuity
of the conditions favourable for the pests and diseases is broken, and
the latter do not have the chance of becoming thoroughly established.
DISEASES SPREAD BY PESTS.--It should be borne in mind that the fewer
the animal pests, the less chance there is for diseases to spread. It
is now well known that many pests, though not necessarily epidemic
themselves, are carriers from plant to plant of certain destructive
fungous, bacterial and virus diseases.
CO-OPERATION.--In a locality of many gardens a co-operative spirit is
essential, since a single neglected garden in an otherwise well-managed
locality will be responsible for discounting the labours of the
neighbours.
(b) Use of Chemicals.
Chemicals are essential in the control of pests and diseases, and
are applied either in the form of sprays or dusts. The former method
is the more usual in this country, but where the water supply is
poor dusts tend to take the place of sprays. Chemicals used for
horticultural purposes are of two distinct kinds--those for the control
of animal pests and those for the control of diseases. The commercial
horticulturist, however, finds it necessary to apply both in the one
spray or dust for the dual purpose of controlling both pests and
diseases. As the present work is concerned with the pests, and not
diseases, only those types of chemicals for the control of the former
will be referred to.
Sprays and dusts are of three kinds, and act upon pests accordingly:
they are either stomach poisons, or act externally on the animal by
actual contact and corrosion, or cause death by fumigation. The kind
used is governed by the feeding habits of the pest; if the latter is
possessed of jaws (woodlice, caterpillars, beetles, etc.), and feeds
by chewing the plant tissues, then a stomach poison is applied and is
swallowed with the food; if the food is the nutrient sap of plants,
and so could not be poisoned, a spray acting by contact is used, as
against such animals as aphids (green fly), scale insects, etc., in
which the mouth-parts are not adapted for chewing, but for puncturing
plant tissues to feed on the sap, much the same as a mosquito punctures
one’s skin and sucks the blood. Fumigants can be used against both the
chewing and sucking pests, the fumes passing into the breathing system.
STOMACH POISONS.--The chief of these are arsenate of lead and Paris
green, though the latter has practically gone out of use. Arsenate of
lead is sold as a paste and as a powder, and is mixed with water to
form a spray, 3lb. of paste, or 1-1/2lb. of powder, to 100 gallons
of water being the proportions used. For garden purposes, smaller
quantities must be kept to this strength.
CONTACTS.--The chemicals used in contact control are red oil, kerosene
and lime-sulphur, but all are also fumigants, lime-sulphur being also a
stomach poison to a limited extent, though best known as a fungicide.
Commercial red oils can be purchased ready for mixing with water
without the necessity of emulsification, and the strength at which each
brand should be used is given by the manufacturers. Though red oils
have mostly replaced kerosene emulsion, many horticulturists still
prefer the latter. It is prepared by dissolving 8oz. of soap in one
gallon of hot water, and then adding two gallons of kerosene, stirring
briskly until emulsification is complete. This is the stock emulsion,
and must be diluted before use, the strengths being one part to six of
water for use in the winter, and one part to fifteen of water for use
in the growing season. Commercial brands of concentrated lime-sulphur
are on the market, and the manufacturers’ directions for their dilution
should be followed.
FUMIGANTS.--The chief fumigants are black-leaf 40, carbon-bisulphide
and calcium cyanide.
Black-leaf 40, in which nicotine sulphate is the effective principle,
is the most useful fumigant on the market, and acts as a most effective
control for sap-sucking, and even some chewing pests. The strength at
which this fumigant is used is one part in 800 parts of water, and is
applied as a spray.
Carbon-bisulphide is a liquid, the gas evolved from it being an
effective fumigant. It is not used as a spray unless emulsified,
its chief use in horticulture being for the fumigation of the soil,
glass-houses, stored seeds and vegetables, and imported plants. It
is very inflammable and extremely volatile, especially under higher
temperatures, the heavy gas being highly explosive when mixed with air.
The amount of carbon-bisulphide to be used varies, according to
circumstances. For soil fumigation a special type of “gun” is on the
market for injecting the bisulphide into the soil, but for ordinary
garden purposes it is sufficient to make holes in the ground with a
stick, pour in the fumigant, and close up the holes. When holes are
made about 18 in. apart, half an ounce of bisulphide to a hole is
sufficient, the depth of the hole varying according to the depth of the
pest to be controlled.
For the fumigation of seeds, bulbs, potatoes, etc., an airtight chamber
is necessary. This is also of value in the control of pests of potted
plants. The dimensions of a chamber will vary according to the demands
made upon it. Carbon-bisulphide gas being heavy, the containers
(shallow dishes) should be placed on a shelf near the top of the
chamber during fumigation. The proportion of fumigant to the air space
varies according to the plants and insects to be fumigated.
For lawn-infesting insects, carbon-bisulphide can also be used in an
emulsion as a spray prepared as follows:--Fifty grams of powdered
resin are gradually added to 135 cc. of a 7 per cent. solution of
sodium hydroxide, previously warmed; 450 cc. of hot water is now added,
and the whole agitated until the resin is completely dissolved, when
50 cc. of oleic acid is also added. To prepare the emulsion, three
parts of this soap solution are thoroughly agitated with seven parts
of carbon-bisulphide until emulsification is complete, which can be
gauged by the creamy-white colour and viscosity. For use dilute in
the proportions of 18 pints of the emulsion with 50 gallons of water,
applying by means of a watering-can or spray-pump at the rate of one
gallon to every square foot of lawn.
Calcium cyanide, on being exposed to the atmosphere, gives off
hydrocyanic acid gas, the evolution of the gas being governed by
temperature and humidity. Calcium cyanide has replaced the old method
of generating the gas by the action of sulphuric acid on potassium
cyanide, and is sold in the form of dusts or granules. In the use of
this material very great care is necessary, since the gas is highly
poisonous, and also scorching of the foliage of plants results if
atmospheric conditions are not considered carefully. With ordinary
care, however, calcium cyanide can be safely handled. It is extremely
effective against all kinds of pests, and can be used to fumigate soil,
glass-houses, or as a dust on plants in the open.
(c) Influence of Natural Enemies.
As stated in the first chapter, plants are to be looked upon as the
primary producers of life (since all animals are directly or indirectly
dependent upon them), and the animals as the consumers. Many of the
latter are destructive to crops grown by man, and become pests, but
others, fortunately, exist upon these pests, and are classed as
beneficial animals; it is the purpose of this section to deal with the
more important of these from a horticultural viewpoint. In New Zealand
such beneficial animals are insects, birds, and the hedgehog.
Insects.
There is a wide range of insects that live at the expense of their
fellows, and without these plant production would be impossible, either
by Nature or by man. These so-called beneficial insects or parasites
are the greatest factor in maintaining within reasonable bounds the
insects that destroy vegetation; they are of much greater value in this
respect than birds. In recent times the utilising of beneficial insects
as a means of pest control has developed as one of the most important
branches of entomological research.
From a general viewpoint, the beneficial insects are to be found mainly
among the groups, including wasps, beetles, flies (two-winged insects)
and lace-wings. The following are some examples:--
Common examples of parasitic insects are the ichneumon wasps
(Fig. 14a), chalcid wasps (Fig. 14b), and ensign wasps, the first being
the most conspicuous, the others less so owing to the minute size of
many of them. A characteristic feature of these forms is the stalk-like
attachment of the abdomen to the thorax and the sting-like ovipositor
of the female, which may be of short or moderate length, sometimes
projecting as a tail-like appendage beyond the end of the abdomen.
Parasites deposit their eggs either upon or within the body of their
victims or hosts, which are eventually destroyed by the larvæ hatching
from the parasites’ eggs. Destructive caterpillars and their pupæ, and
also aphides, are attacked by these wasp-like parasites, which in many
cases restrict their depredations to one or a limited number of host
species, while others are more general in their selection. Another
group, the predaceous wasps, should be mentioned here. These insects in
the adult state are hunters, and capture and paralyse by stinging such
insects as caterpillars and flies, as well as spiders, which are stored
in nests or cells for the nourishment of the predators’ offspring.
Important natural enemies of aphides and young caterpillars are the
hover-flies, which can be easily recognised by their manner of flight.
They are two-winged insects (Fig. 14c), and when on the wing hang
motionless, as if suspended by some unseen means, to suddenly dart off
with marvellous rapidity, until they hang motionless as before. These
flies lay their eggs upon the foliage of plants infested by aphids or
caterpillars, and from these eggs legless and headless larvæ emerge
(Fig. 14d), and commence to search for and feed upon their victims.
Another important group of two-winged flies is the tachinids. They
are rather robust, usually very bristly (Fig. 14e); they vary in size
from that of a large blue-bottle to comparatively minute forms. The
tachinids lay their eggs either upon their hosts or on the food plants
of the latter, where they can be swallowed; some tachinids give birth
to living larvæ, which crawl about in search of their victims.
Among the beneficial beetles are the well-known ladybirds (Fig.
14f); they are mostly oval in outline, dome-shaped above and flat
below, while many of them are spotted by yellow, red, or white in a
characteristic manner, though others are of one uniform colour. The
eggs are laid on plants infested by the aphides and scale insects
upon which the beetles and their larvæ (Fig. 14g) feed. There are
other kinds of beetles of importance as predators, such as the common
tiger-beetle, but they are not especially selective in their types of
victims.
A very valuable group of insects includes the lace-wings or
aphis-lions. The adult insects (Fig. 14h) carry the seemingly
over-large lace-veined wings roof-like over the small body; the larvæ
are alligator-like (Fig. 14i), and possess a pair of caliper-shaped
jaws, by means of which they capture their prey. The eggs are laid
directly on plants or are attached at the end of long stalks.
Birds.
It is generally recognised that birds are a very important aid in
keeping destructive insects in check, though it is well-known that a
great deal of damage can be done by these animals. Without a systematic
study of the stomach contents of birds, it is not possible to decide
when a species is beneficial or injurious, and in New Zealand no such
study has been made; practically all the information we have is based
on field observations, which are, unfortunately, influenced largely
by the outlook of the observer, and are thus misleading. Though some
species subsist for the most part on insects, most land-birds have a
mixed diet of vegetable and animal food, but they specialise on an
insect diet when rearing their young and when moulting.
[Illustration: FIGURE 14.
(a) An ichneumon (natural size 1-1/4 in); (b) a chalcid (natural size
1-25 in); (c) a hoverfly (natural size 1/8 in); (d) hoverfly larva
(natural size 1/4 in); (e) a tachinid fly (natural size 1/4 in); (f)
a ladybird beetle (natural size 1/5 in); (g) ladybird larva (natural
size 1/4 in); (h) lacewing (natural size 1/4 in); (i) lacewing larva
(natural size 1/5 in).]
Based on the nature of their diet, birds fall into three principal
groups: (1) those feeding almost solely upon seeds and fruits; (2)
insectivorous birds feeding on insects and other animals; and (3) the
omnivorous species feeding both on insects and vegetable matter. The
seed-feeding birds are a potential menace to the agriculturist, though
in New Zealand the native species are fundamental to the well-being of
the native forests; the insectivorous birds are obviously beneficial,
though they devour both destructive and useful insects; while the
omnivorous birds may be either useful or harmful, according to the
circumstances. It should be remembered that, no matter what the food of
the adult bird may be, most species give their young a diet of insects
or other animal matter. When it is realised that the weight of nestling
birds increases from one-fifth to one-half each day, requiring at times
more than half the weight of the nestling in food, one can better
visualise the enormous quantities of insects daily destroyed for this
purpose. Consider the common house sparrow, which is usually condemned:
an analysis of the nestling diet has shown that it consisted of 40 per
cent. grain and 60 per cent. insects and related forms, while that of
the adult comprised 75 per cent. grain and 25 per cent. insects, etc.
To summarise the situation, it may be said that, on the whole, enormous
numbers of insects are destroyed by birds each year, and, unless
allowed to become abnormally abundant, the benefit derived from birds
outweighs the damage they may cause.
Hedgehog.
The hedgehog was first introduced by the Canterbury Acclimatisation
Society in 1870, and later by other societies and private individuals.
The animal is now very abundant in many parts of the Dominion. Though
condemned and destroyed by some people, who consider it a menace to
eggs, chickens and even vegetables, the hedgehog is really a very
useful animal, in that, being a night prowler itself, it destroys
numerous nocturnal pests, such as slugs and snails, earwigs, grass
caterpillars and cut-worms.
The hedgehog, on the approach of winter, constructs a nest in some
suitable place, where it becomes torpid and hibernates. On the advent
of spring, it becomes active once more, and during summer produces a
litter of four young; a second litter is sometimes produced in the
autumn.
INDEX.
Page
Acacia, 32, 38
_Agrotis ypsilon_, 52
_Algæ_, 14, 15
Almond, 35, 38, 64
Amaryllis, 66
American blight, 47
_Amœbæ_, 15
_Anguillulina dipsaci_, 72
Animal Kingdom, Divisions of, 8
_Aphelinus fuscipennis_, 40
_Aphelinus mali_, 47
_Aphelinus mytilaspidis_, 38, 40
Aphides, 42
Aphis-lion, 28, 78
_Aphis persicæ-niger_, 44
Apple, 34, 35, 37, 38, 40, 41, 47, 48, 61, 64, 67
Apple leaf-hopper, 48
Apple leaf-roller, 51
Apple mealy-bug, 34
Apple mussel-scale, 30, 37
Apple red-mite, 57
Apricot, 35, 36, 38
Army-worms, 54
Arsenate of lead, 76
Asexual, 42
Ash, 38
Asparagus, 36
_Aspidiotus hederæ_, 40
_Aspidiotus perniciosus_, 38
_Asterolecanium variolosum_, 37
Austrian pine, 46
Bacteria, 14, 15
Bag-moth, 56
Baker’s mealy-bug, 35
Beet eelworm, 72
Beetles, 56
Begonia, 34
Beneficial insects, 77, 78
Birds, 79
Blackberry, 36, 41
Blackbird, 35
Black cherry-aphis, 44
Black-currant, 36, 44
Black-leaf 40, 76
Black peach-aphis, 44
Black scale, 40
Blister-mites, 70
Blue-gum, 59
Borers, round-headed, 64
Breathing systems of insects, 21
_Brevicoryne brassicæ_, 45
Briar, 41
Bronze beetle, 58
Broods of insects, 22
Broom, 52
Brown-beetle, 58
Brown-mite, 68
Brussels sprouts, 45
_Bryobia prætiosa_, 68
Bulb-eelworm, 72
Bulb-mite, 68
Bulb or Narcissus flies, 66
Cabbage, 45, 48, 55
Cabbage aphis, 45
Cabbage green-fly, 45
Cabbage-tree, 56
Cabbage-tree moth, 56
Cabbage-tree scales, 38
Cabbage white butterfly, 55
Calcium cyanide, 76
_Caliora limacina_, 59
Camellia, 35, 36, 37, 40
Camellia scale, 37
Carbon-bisulphide, 76
Caterpillars, 51
Caterpillars in lawns, 65
Cauliflower, 45, 55
_Cecidomyia oleariæ_, 60
Cereals, 54
Chalcid wasps, 78
Chemicals, 75
_Chermes pini_, 46
Cherry, 38, 44, 59
Cherry-aphis, black, 44
Cherry slug, 59
Chitin, 17
Chrysalis, 25
Chrysanthemum, 64
_Chrysomphalus aurantii_, 40
_Chrysomphalus rossi_, 40
Cicada, 28
Cineraria, 24, 34, 56, 64
Citrophilus mealy-bug, 34
Citrus, 32, 35, 36, 40, 64, 67
Click-beetles, 65
Clover, 52
Coccids, 29
_Coccus hesperidum_, 36
Cockchafers, 57
Cockroach, 17, 27
Cocoon, 25
Codlin moth, 61
Comstock’s mealy-bug, 35
Contact sprays and dusts, 76
Convolvulus, 54
Coprosma, 40
Cornicles, 42
Cottony-cushion scale, 30, 32
Crayfish, 17
Crickets, 27, 51
Crocus, 68
Crop rotation, 75
Cruciferous crops, 45
Cryptolæmus ladybird, 34
_Cryptolæmus montrouzieri_, 34
Curl-grubs, 58
Currant, 37, 38, 61, 68
Currant clear-wing borer, 61
Cuticle, 17
Cut-worms, 52
_Cydia pomonella_, 61
Daffodil, 72
Development of insects, 22
Diamond-backed moth, 52
Digestive system of insects, 21
Douglas fir, 32, 46
Dusts, 75
Earthworms, 15
Earwig, 27, 50
Easter lily, 68
Eelworms, 8, 72
Eggs of insects, 22
Elder, 35
Eleagnus, 37
Elm, 38, 47
Elm-leaf aphis, 42, 47
Elytra, 58
Ensign wasps, 78
_Eriococcus coriaceus_, 35
_Eriophyes pyri_, 70
_Eriosoma lanigerum_, 47
Eucalypts, 35, 59
Eucalyptus tortoise beetle, 59
_Eucolaspis brunneus_, 58
_Eulecanium berberidis_, 37
_Eulecanium corni_, 36
_Eumerus strigatus_, 66
Euonymus, 35, 37, 40
European earwig, 50
European red-mite, 67
Fantail, 35
Ferns, 34, 36
Fig, 34, 35, 36, 40
Flax, New Zealand, 38
Flea-beetles, 58
_Forficula auricularia_, 50
Fruit lecanium scale, 36
Fumigants, 76
Fungi, 14, 15
Galls, 42
Galtonia, 66
Gladiolus, 72
_Gnorimoschema plæsiosema_, 62
Goat-willow, 64
Golden oak-scale, 37
_Gonipterus scutellatus_, 59
Gooseberry, 35, 36, 37, 38, 64
Gorse, 32
Grape louse, 46
_Grape phylloxera_, 46
Grape-vine, 34, 35, 36, 37, 40, 46, 51, 67
Grass caterpillars, 65
Grasses, 64, 65
Grass-grubs, 57, 64
Grasshopper, 17, 51
Greasy cut-worms, 52
Green-fly of cabbage, 45
Green-house thrips, 49
Green-house white-fly, 48
Green manuka beetle, 58
Green peach-aphis, 44
Groundsel, 24, 56
Grub-proofing lawns, 64
Gum-tree scale, 35
Gum-tree weevil, 59
_Habranthus_, 66
_Habrolepis dalmanni_, 37
Hawk moth, 54
Hawthorn, 37, 38, 59, 67
Hedgehog, 80
_Heliothrips hæmorrhoidalis_, 23
Hemispherical scale, 36
_Heterodera radicola_, 73
_Heterodera schachtii_, 72
Hibernation, 23
Holly, 35, 36
Honey-bee, 19
Honey-dew, 29, 42
Honey-tubes, 42
Hop, 68
Horse chestnut, 35
Hover-flies, 66, 78
Hyacinth, 66, 68, 72
Hydrangea, 35
Hydrocyanic-acid gas, 77
_Hypopus_, 68
_Icerya purchasi_, 32
Ichneumon wasps, 78
Importation of pests, 74
Insects, proportion of, 7
Insignis pine, 46, 51
Invertebrates, 7
Iris, 35
Ivy, 35, 36, 40
Japonica, 36
Karaka, 40
Kerosene, 76
Kowhai, 52
Kowhai moth, 52
Kumara, 54
Lace-wing, 34, 78
Ladybird beetles, 78
Larch, 46
Larger narcissus fly, 66
Larva, 24
Laurel, 35, 36
Lawns, 64, 65
Lead arsenate, 76
Leaf-hoppers, 48
Leaf-mining flies, 64
Leaf-rollers, 51
Leech, 59
Lemon, 35, 40
_Lepidosaphes ulmi_, 37
_Lepisma saccharina_, 26
Lettuce, 55
_Leucaspis cordylinidis_, 38
_Leucaspis stricta_, 38
Leucojum, 66
Life-cycle of insects, 22
Lime-sulphur, 76
Loganberry, 41
Long-horned beetles, 64
Long-tailed mealy-bug, 34
Lupins, 52
_Macrosiphum rosæ_, 47
Magpie-moth, 24, 55
Management of garden, 74
Manure, 74
Mealy-bugs, 29, 30, 32, 34
Mealy-wings, 43
_Mecyna maorialis_, 52
_Merodon equestris_, 66
Metamorphosis, 24
_Micromus tasmaniæ_, 28, 34
Millepedes, 71
Mites, 67
Moulting, 22
Mouth appendages of insects, 19
Mulberry, 35, 36
Mussel scale of apple, 30, 37
Mustard, 44, 45, 48, 52
Myrtle, 36
_Myzus cerasi_, 44
Narcissus, 66, 68, 72
Narcissus flies, 66
Natural enemies, 77
Nectarine, 36, 44
Nervous systems of insects, 21
Nicotine-sulphate, 76
Northern Spy, 47
_Novius cardinalis_, 32
_Nyctemera annulata_, 24, 55
Oak, 37, 51
Oak-scale, 37
_Odontria zealandica_, 57, 64
_Oeceticus omnivorus_, 56
Oleander, 34, 35, 36, 40
Oleander-scale, 40
Olearia forsteri, 60
Olearia gall-midge, 60
Olive-scale, 30, 35
Onion, 66
Orange, 35, 40, 51
Orange-scale, 40
Orchids, 36, 40
_Orcus chalybæus_, 36, 40
Oviparous, 42
Ovipositor, 21
Palms, 34, 35, 36, 40
_Paratetranychus pilosus_, 67
Paris green, 76
_Paropsis dilatata_, 59
Parthenogenetic, 42
Passion vine, 34
Pastures, 64, 65
Peach, 35, 36, 38, 44, 48, 59
Peach-aphis, black, 44
Peach-aphis, green, 44
Pear, 34, 35, 36, 37, 38, 40, 41, 50, 59, 60, 61, 70
Pear and cherry saw-fly, 59
Pear and cherry slug, 59
Pear-leaf blister mite, 70
Pear-midge, 60
Pelargonium, 51
_Pemphigus populi-transversus_, 48
Pepper-tree, 35
_Perrisia pyri_, 60
Persimmon, 35
Phormium, 34
_Phthorimæa operculella_, 62
_Phylloxera vastatrix_, 46
_Pieris rapæ_, 55
Pine-tree chermes, 46
Plant food, 12
Plant-lice, 42
Plum, 34, 35, 36, 38, 40, 44, 48, 59
Plum-aphis, 48
_Plutella maculipennis_, 52
_Pontania proxima_, 60
Poplar, 35, 37, 38, 48, 64
Poplar Gall-aphis, 42, 48
Porina, 65
Potato, 34, 62, 72
Potato sickness, 72
Potato tuber-moth, 62
Predaceous wasps, 78
Privet, 38
Protozoa, 8, 15
_Pulvinaria camelicola_, 37
Pupa, 25
Puparium, 25
_Pyronota festiva_, 58
Quince, 38, 40, 41
Radish, 55
Ragwort, 24, 56
Rape, 45, 48
Raspberry, 36, 41, 67
Red currant, 44
Red oil, 76
Red orange-scale, 40
Red spider, 68
_Rhizoglyphus hyacinthi_, 68
Rhododendron, 47
_Rhophalosiphum nymphææ_, 48
_Rhophalosiphum persicæ_, 44
Root-knot eelworm of tomato, 73
Rose, 35, 38, 40, 41, 47, 51, 58, 67
Rose-aphis, 42, 47
Rotation of crops, 75
Round-headed borers, 64
_Saissetia hemispherica_, 36
_Saissetia oleæ_, 35
San José scale, 32, 38
Scale insects, 29
Scylla, 66
Seasonal history of insects, 22
Seeds, damage to, 65, 66, 71
_Sesia tipuliformis_, 61
Shallot, 66
Shepherd’s purse, 44, 52
Silver-fish, 26
Slugs, 8, 71
Smaller narcissus fly, 66
Snails, 8, 71
Soil fumigation, 76
_Sphinx convolvuli_, 54
Sphinx moth, 54
Spiders, 8, 67
Sprays, 75
Springtails, 66
Spruce, 46
Steam sterilisation, 74
Steel-blue ladybird, 36, 40
Stomach poisons, 76
Strawberry, 64, 68
Subterranean grass caterpillars, 65
Sulphur smudge, 58, 65
Syrphids, 66
Tachinids, 78
_Tetranychus telarius_, 68
Thrips, 27, 48
Thrush, 35
Tobacco, 54, 73
Tomato, 47, 54, 62, 73
Tomato root-knot eelworm, 73
Tomato stem-borer, 62
Tortoise beetle, 59
_Tortrix postvittana_, 51
Tree-lucerne, 64
_Trialeurodes vaporariorum_, 48
Tui, 35
Tulip, 66, 68
Turnip, 45, 48
Turnip-fly, 57
Turtle-scale, 36
_Typhlocyba australis_, 48
Vallota, 66
Vegetable caterpillars, 65
_Venusia verriculata_, 56
Vertebrates, 7
Violet, 68
Viviparous, 42
Walnut, 35
Watercress, 46, 52
Water lilies, 48
Wattle, 32, 41
Wax-eye, 35
Weta, 17
White butterfly, 55
White-flies, 48
Willow, 35, 37, 38, 60, 68
Willow saw-fly, 60
Wings of insects, 20
Wireworms, 65
Wistaria, 34, 35, 36
Woodlice, 8, 70
Woolly-aphis, 42, 47
Woolly-bear, 24, 56
End of Project Gutenberg's Garden Pests in New Zealand, by D. Miller