Identify and Control Insects on Fruit and Nut Crops

Unit D: Controlling Pests and
Diseases in the Orchard
Lesson 3: Identify and Control Insects of
Fruits and Nuts
1

Terms
• Eggs
• Nymph
• Adult
• Instar
• Imago
• Larvae
• Pupa
2

I. Understanding the vocabulary used when
describing insects will help when controlling
insects in the orchard. Some common terms
include:
A. Most insects develop from eggs which contain
the developing nymph.
B. Nymph is the name given to the young stages of
those insects which undergo a partial
metamorphosis. The nymph is usually quite
similar to the adult except that its wings are not
fully developed. It normally feeds on the same
kind of food as the adult.
3

C. The adult is the mature form of the insect which has
the ability to reproduce.
D. Instar is the stage in an insect's life history between
any two moults. A newly-hatched insect which has
not yet moulted is said to be a first-instar nymph or
larva. The adult (imago) is the final instar.
E. Larvae is the name given to a young insect which is
markedly different from the adult: caterpillars and fly
maggots are good examples.
F. The 3rd stage in the life history of butterflies and
other insects undergoing a complete metamorphosis
during which the larval body is rebuilt into that of the
adult insect is called a pupa. It is a non-feeding and
usually inactive stage.
4

II. There are a number of insects which can
cause damage in a fruit and nut orchard.
The most common insects and their control
methods are covered below. This is not an
all-inclusive list and other insects may occur
in your area.
5

A. Leopard moth (Zeuzera pyrina)
1. Life cycle and description
a. oval and salmon to orange-yellow color about 1.5
mm long. Females will lay 400-600 eggs under
the bark of trees.
b. Adults Leopard Moths have a furry white thorax
with six black spots.
i. The wings are heavily spotted and are about
35–60 mm long.
ii. Females are larger,
iii. The moth flies from June to September
depending on the location.
c. Larvae will hatch in about 10 days after eggs are
laid.
d. Soon after they will burrow into the nearest bud,
twig or branch crotch.
6

e. They will enter the pith and grow to about
25 mm by the end of the first season.
f. In fall, larvae bore tunnels that slant
upward, 50 mm or more below the bark
surface, where they remain dormant over
winter.
g. Larvae resume feeding the following
summer, pass a second winter in
dormancy, and begin pupation the second
spring after the eggs hatch.
h. Pupation takes about 4 weeks.
i. The pupal cases remain in the exit holes
and is one method of determining their
existence in the orchard.
7

2. Damage
a. The caterpillar feeds on the fruit
and nut trees.
b. It can burrow inside the
branches and feed for up to two
years where it will emerge and
pupate under the bark.
c. The earliest signs of damage will
be girdled or broken twigs.
9

3. Control
a. It is difficult to control this pest once it has
burrowed into the stems and branches.
b. Controlling the adults before they lay eggs or
the caterpillars before they burrow into the
stems and branches will ensure control in the
next year.
c. The best control is birds, also remove any
infected branches and destroy them by
burning.
d. Insecticides can be used in the tunnels.
e. Since females do not move far from where
they pupated to lay their eggs, space trees far
enough so that the moths will not move to
other trees.
11

B. Apple aphid (Aphis pomi)
a. Eggs are shiny black and oval shaped.
b. They are generally found on smooth twigs
and water sprouts.
c. The green-colored young, called nymphs,
begin to hatch from overwintered eggs as
soon as shoot leaves are rapidly
expanding.
i. The nymph is about 1.5 mm long,
yellow-green to dark green and oval
shaped, generally found on smooth
branches or leaf undersides.
12

d. The adult can be winged or wingless
about 3 mm long and bright green.
i. The adult will commonly be
found on the underside of leaves.
e. The first aphids produced in the
spring are generally female who
produce live young asexually.
f. Towards the end of the season both
male and females are born so that
eggs can be produced for
overwintering.
13

g. During the spring and summer,
females produce live young without
mating.
h. In addition, they can complete a life
cycle in as short as one week during
the warm summer months.
i. The short generation time and
ability of these aphids to reproduce
asexually allows them to rapidly
increase their populations and
feeding injury to apple trees.
14

Nymph
Nymph
Adult
Adult laying eggs
Eggs
15

2. Damage
a. Aphids feed by sticking their mouthparts into
the leaf and sucking out the sap.
b. Leaves affected by aphids will often appear
dried and shriveled. Aphids produce a
secretion called honeydew.
c. If large populations of aphids are present this
honeydew can drip down onto fruit or other
parts of the tree and cause sooty mold.
d. This will reduce marketability of fruit and
weaken the tree.
e. Established trees are rarely damaged as any
minor leaf loss will not have a major impact
on fruit production.
f. Young trees can be greatly damaged or even
killed if aphid infestations are too high.
17

3. Control
a. Natural enemies include lady beetles,
lacewings, parasitic wasps and certain
fungi.
b. Organic insecticidal sprays are effective
and often include liquid dishwashing
soap.
c. Because of their size, aphids are often
easily controlled by a strong blast of
water to displace them from the leaves
of the affected plant.
d. Dry weather also greatly reduces the
population.
19

C. Wooly Apple Aphid (Eriosoma lanigerum)
a. Wooly Apple Aphid produces live young.
b. The nymphs are about 1.25 millimeters long and
are reddish purple in color covered in a white
cottony wax.
c. Wooly Apple Aphids (WAA) overwinters as
nymphs.
d. The adults are about 1.5 millimeters long and
similar in color to the nymph.
e. Females are generally observed on the apple tree,
males are rare.
f. Females produce live young without mating.
20

Left: first instar aphid. Middle: female carrying one egg. Right: Male
aphid
21

2. Damage
a. WAA can attack the roots and
cause galls.
b. Over several seasons the galls
will increase in size and cause
major root damage.
c. Similar to the Apple Aphid, the
WAA produces honeydew
causing sooty mold on the fruit
and tree.
22

3. Control
a. The most important natural enemies are green
lacewing larvae, lady beetle adults and larvae,
and syrphid fly larvae.
b. Flowering plants in or on the borders of orchards
provide nectar and pollen, which helps maintain
and attract natural enemies.
c. If replanting or starting a new orchard, plant
resistant rootstock.
d. The Malling Merton (MM) rootstock series,
MM.106 and MM.111, have been bred to be
resistant to WAA,
24

e. WAA are easily controlled with
broad-spectrum insecticides.
f. In order to significantly increase
insecticide efficacy, it is
recommended a horticultural oil
be added to the tank mix.
g. Without horticultural oil the
insecticide has difficulty
penetrating the waxy covering of
the colony.
25

D. Green peach aphid (Myzus
persicae)
a. Eggs are deposited on Prunus spp.
trees.
b. The eggs measure about 0.6 mm long
and 0.3 mm wide, and are elliptical in
shape.
c. Eggs initially are yellow or green, but
soon turn black.
26

d. Mortality in the egg stage
sometimes is quite high.
e. Nymphs begin greenish but turn
yellowish.
f. Adults can be winged or
wingless.
g. They have a black head and
thorax and a yellowish green
abdomen.
h. They measure 1.8 to 2.1 mm in
length. 27

2. Damage
a. Green Peach Aphids will travel to any
plant available and will deposit a few
young and then move on to another
place.
b. Aphids will then begin to colonize on
peach trees when the leaves begin to
turn color and fall off.
c. The Green Peach Aphid damages
trees much like the other aphids- by
sucking out the sap from leaves and
tender stems.
29

d. The major damage caused by
the Green Peach Aphid is
through the transmission of plant
viruses.
e. Both nymphs and adults can
spread the virus, but adults can
spread it more because of their
mobility.
f. Over 100 viruses have been
identified to be carried by the
aphids.
30

3. Control
a. Natural enemies of the Green
Peach Aphid are the same as
the other aphids- lady
beetles, lacewings and
parasitic wasps and fungi.
b.Using horticultural oils and
insecticides are a very
effective way to control large
outbreaks.
32

E. San Jose scale (Aspidiotus
perniciosus)
a. Partially mature nymphs overwinter
on branches and in spring developed
into winged males or females which
do not move.
b. When the weather is warm and trees
have budded out, females will lay
eggs which hatch immediately.
c. The young are called crawlers.
33

d. They look for new shoots and
settle to feed until adults where
they will overwinter to complete
the cycle again.
e. Multiple generations per year are
possible.
f. Scale is a very tiny insect covered
in a scab-like structure.
g. If the scale is removed a yellow
body can be seen.
34

2. Damage
a. San Jose scale can infest branches,
shoots, leaves, and fruit. Adults and
nymphs suck plant juices and cause
considerable damage. They have
been known to seriously weaken
branches and main scaffold limbs,
thus causing permanent injury to
mature trees. Crawlers settling on
fruit may cause fruit spotting.
36

3. Control
a. Oil sprays can be effective in
controlling low to moderate
populations of San Jose Scale.
b. Native predators are also very
effective.
c. Predators include the
twicestabbed lady beetle,
Chilocorus orbus, and another
small beetle Cybocephalus
californicus.
38

F. Olive scale (Aspidiotus hederae)
a. The adult female scale is about 0.10
(2.5 mm) inch long, with a grayish,
oval, waxy covering.
b. The male scale is more elongate
with a black spot at one end.
c. If the coverings are removed, the
scale bodies of both sexes are
reddish purple.
40

2. Damage
a. Olive scale feeds on twigs,
leaves, and fruits.
b. The first brood will emerge early
in the growing season and eat
the young rapidly growing fruit.
c. A second brood in mid-season
causes purple spotting on the
green fruit.
d. Heavy infestations greatly reduce
the productivity of the tree.
42

3. Control
a.Olive scale is effectively
controlled by natural
enemies such as Aphytis
maculicornis and
Coccophagoides utilis.
b.Chemical treatment is rarely
needed unless the biological
control is disrupted.
43

G. Citrus Whitefly (Dialeurodes citri)
a. Adults are white and have a distinctive Y-shape on
their back.
b. Whiteflies develop rapidly in warm weather, and
populations can build up quickly in situations
where natural enemies are destroyed and
weather is favorable.
c. They grow in stages.
i. the first nymph is a very small crawler, later
nymph stages settle and remain immobile
and are flattened and oval.
ii. Older nymphs do not move.
iii. Finally a winged adult emerges.
iv. All stages feed by sucking juices from leaves.
44

Nymph
Nymph
Adult Adult and eggs
Colony Citrus spp.
45

2. Damage
a. Whiteflies suck sap out of the phloem.
b. Large populations can cause massive leaf
death.
c. Whiteflies produce honeydew like aphids
so black sooty mold can occur.
d. Low levels of whiteflies are not generally
damaging but some adults can carry plant
pathogens.
3. Control
a. Large populations of whiteflies are hard to
control and can be adequately controlled
by beneficial insects.
46

H. Citrus Leafminer (Phyllocnistis
citrella)
a. Adults are very small, about 4 mm
wingspan, with white and silvery
iridescent scales on the forewings.
b. There is a noticeable black spot on
each wing tip.
c. The hind wings and body are white,
with long fringe scales extending
from the hindwing margins.
48

d. Larvae are very small (3mm) and
translucent yellow-green.
e. They can be found on the underside of
leaves creating meandering paths inside
the leaf.
f. Usually only one leaf mine is present
per leaf but heavy infestations may
have two or three mines per leaf.
g. larvae are protected within the leaf
during their feeding cycle.
h. Larvae have four instars and
development takes from five to 20 days.
49

i. Pupation is within the mine in
a special pupal cell at the leaf
margin, under a slight curl of
the leaf.
j. Pupal development takes six
to 22 days.
k. Adults emerge about dawn
and are active in the
morning; other activity is at
dusk or night.
50

2. Damage
a. Larvae mine into the leaves of citrus
trees.
b. They eat through the leaf destroying
tissue and disrupting nutrient transfer.
(see picture on bottom right of slide
#51)
3. Control
a. Biological control and application of oil
are suitable methods to help reduce
populations.
b. Because of their position inside the leaf,
larvae may be hard to eliminate.
52

I. Codling moth (Cydia pomonella)
a. The Codling Moth is the main pest of apple.
b. The adult moth is greyish with light grey and
copper stripes on its wings, with a wingspan
of 17 mm.
c. The females lay eggs on fruit or leaves and the
black-headed yellow larvae attack the fruit
immediately upon hatching.
d. Each larva burrows into the fruit, eats for
around three weeks, then leaves the fruit to
overwinter and pupate elsewhere.
e. They mainly feed on the seeds of the apple.
54

2. Damage
a. Larvae bore into the interior of
the apple consuming the seeds
and apple.
b. The infected fruits will often
abort and fall off the tree.
c. Once the caterpillar has entered
the apple it is of no use as a
marketable fruit.
56

3. Control
a. Insecticides are generally the best method of
control for Codling Moths.
b. Because of their location inside the apple,
they are protected from any natural enemies,
leaving biological control out of the control
methods.
c. Another method for control and sampling,
'trunk banding', consists of wrapping a
corrugated cardboard strip around the tree
trunk.
d. Larvae making their way back to the tree to
pupate after the infested fruits are aborted
will use bands as pupation sites.
e. Bands may then be removed and burned.
58

J. Red spider mite (Tetranychus
telarius)
a. The adult female is approximately 0.65
mm long, rotund oval in shape, and pale
yellow or greenish with two
characteristic lateral dark green or black
spots on the body.
b. The adult male is slightly smaller than
the female and has a narrower, more
pointed abdomen.
c. Eggs are spherical and very small (about
0.1 mm in diameter).
59

d. Nymphs vary in coloration,
depending on their host plant, but
are normally pale yellow, pale
green, or beige, with two green
spots.
e. Frequently the end of the abdomen
is a dark green.
f. The first stage is six-legged while the
second stage is eight legged.
g. The adult females overwinter to
begin the life cycle the next season.
60

Eggs
Mites’ clumping habit
Adults
61

2. Damage
a. The Red Spider Mite will attack
grapes, raspberries and tree
fruits.
b. They damage the plant by
piercing the plant cells and
sucking out the contents.
c. This results in a noticeable pale
colored spotting on the topside
of the leaf.
62

3. Control
a. There are a number of miticides
available for mite control in the
orchard.
b. However, mites rarely reach a level
that can cause major economic
damage to an orchard.
c. In general, if fruit trees are healthy
and well established a mite
population will not have a major
impact on production.
64

K. Oriental mite (Eutetranychus
orientalis)
a. Adult females are larger than the
males.
b. They are oval and flattened and are
often pale brown through brownish-
green to dark green.
c. The citrus brown mite can only be
identified by the adult male and is
easily mistaken for the Texas citrus
mite (E. banksi).
65

d. Females begin to lay eggs when only a
few days old.
e. The eggs are laid along the main veins
of the host plant leaves and hatch after
a week or less.
f. The length of the entire life cycle is
around 10-12 days.
g. Adult longevity lies between 1 and 3
weeks.
h. Under optimal conditions, there can be
10-30 generations per year, depending
on the geographical location.
66

Oriental red mite, left male on top of a darker female. Right
males clustering around a pre-adult female
67

2. Damage
a. The presence of E. orientalis can be detected
by discoloration of the host leaves and pale-
yellow streaks along the midribs and veins.
3. Control
a. Oriental mites are primarily found on citrus.
b. There are a number of miticides available for
mite control in the orchard.
c. However, mites rarely reach a level that can
cause major economic damage to an orchard.
d. In general, if fruit trees are healthy and well
established a mite population will not have a
major impact on production.
68

This is damage
done by Oriental
Mites on a palm.
The damage will
look similar on
fruit trees-
discoloration of
the leaf
especially along
the midrib.
69

Review/Summary
1. What is the common terminology
used to describe an insect’s life
cycle?
2. What are some common orchard
insects and how can they be
controlled?
70

Identify and Control Insects on Fruit and Nut Crops

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