This document discusses several lepidopteran pests that affect crops like cotton and rice. It provides details on the lifecycles, damage caused, and control methods for the following pests: 1. Pectinophora gossypiella (Pink Bollworm), a serious cotton pest whose larvae damage cotton bolls and seeds. 2. Tryporyza incertulas (Yellow Stem Borer), a rice pest whose larvae bore into and feed inside rice stems. 3. Cnaphalocrocis medinalis (Rice Leafroller), whose larvae feed on rice leaves and cause stripping. 4. Nymphula depunctalis (Rice

1. Lepidopteran pests

2. Lepidoptera
• The Lepidoptera is an order of insects that
includes moths and butterflies (both are
called lepidopterans).
• Lepidopteran species are characterized by
more than three derived features, some of the
most apparent being the scales covering
their bodies and wings, and a proboscis.

3. • butterflies and moths are holometabolous, meaning
they undergo complete metamorphosis.
• The larvae are commonly called caterpillars, and are
completely different from their adult moth or butterfly
forms, having a cylindrical body with a well-developed
head, mandible mouth parts, three pairs of thoracic
legs and from none up to five pairs of prolegs.
• As they grow, these larvae change in appearance, going
through a series of stages called instars.
• Once fully matured, the larva develops into a pupa.

6. Pectinophora gossypiella (Saunders)
The Pink Bollworm
It is a serious pest of cotton

7. • Adult is a small moth having wingspan of 10-
15 mm, dark brown, with irregular black
markings on the fore wing. Hind wing silvery
gray with no distinct markings.

8. • Fecundity is about 150 eggs/female.
• Eggs are flattened, pale yellow with striated
surface and laid in the night on bracts, buds or
flowers, singly or in small groups.
• Incubation period is 4-6 days.
• Larvae are pinkish in color with brownish head and
10 mm when full grown.
• Then it penetrates the lint until it reaches the
seed, which also it bores and damages.

10. • There are four larval instars and total larval
development takes 20-30 days depending on
temperature.
• Larvae overwinter by curling inside cotton seeds
and become active again in April.
• Pupation takes place either in the lint or in
debris or under bracts or bark on the plant.
• Pupal period is 7-10 days and total life cycle is
completed in 4-5 weeks

13. Cultural control:
• Threshing and thoroughly burying all plant
remains after cotton.
• killing the larvae within seeds or lint bales by
heating to about 60ºC.
• Mass trapping with long-lived pheromone
traps.

14. • Chemical control: Organophosphates were
used in the past to control the pest
• Genetically modified cotton: The use of
modified Bt cotton, which expresses toxins
from Bacillus thuringiensis (Bt), has reduced
the need for pesticides.

15. Tryporyza incertulas
The Yellow Stem borer

16. • This is primarily a pest of rice but also has
been recorded to feed on maize and some
wild grasses.

17. • Adults show sexual dimorphism.
• Eggs are oval, flattened and whitish in colour.
Incubation period of eggs is 5-8 days.
• Larvae are pale yellow in colour with a brownish
head, 20 mm long and bore into the stem near
the node.
• They usually feed on the lower part of the stem
and migrate from one plant to another to mature.
• There are 6 larval instars and larval development
takes 20-27 days.

18. • Pupation takes place inside a whitish silken
cocoon within the rice stem, near the root-
stem joint.
• Before pupation larva cuts an exit hole on the
stem, above the surface of water and covers it
with a silken web as an exit for emerge.
• Pupal period is 9-10 days or longer in cold
weather. Total life cycle takes about 45 days.

21. Damage
• The larva feeds inside the stem and makes
gallery causing dead heart in younger plants.
The flowering plants show white head.

22. Control
• Collection and destruction of egg masses and
plants showing dead hearts helps to reduce
pest population, particularly in nurseries.
• Burning of stubbles or ploughing the field
after harvesting is a good cultural practice.
• Early or late planting is recommended in
areas of heavy infestation.

23. • The following natural enemies keep the pest
population under check :
• Egg Parasites: Trichogramma sp.
• Larval parasites: Amauromorpha accepta
schoenobii; Isotima javensis.
• Larval-pupal parasite: Trichomma sp.

24. Cnaphalocrocis medinalis
Rice leafroller
• The larvae are considered a pest on Oryza sativa and
others.

25. • The moth is very active, bright yellow or straw in
colour with two distinct wavy lines in the fore
wing and one wavy distinct line in the hind wing.

26. • Eggs are laid singly or in groups arranged in longitudinal
rows on the undersurface of the leaves which are scaly
white in color.
• Incubation period is 4–8 days.
• 5–6 larval instars are found, larval period is about 22–
23 days.
• It pupates with in the infested leaf fold for a period of
6–7 days.
• The fully grown caterpillar is green in color and is
16.5mm long.
• The total life cycle completed in about 5 weeks.

27. • Once protected in leaf roll , the larvae scrape
and feed on the green tissues (the mesophyll
layer) of the rice leaves, resulting in the
appearance of linear, pale-white stripe
damage.

29. Control
• Host-Plant Resistance
Several rice lines transformed with toxin genes from Bacillus
thuringiensis (Bt) have been shown to be highly resistant to C.
medinalis .
• Cultural Control
• Wider spacing and low usage of nitrogenous fertilizer decrease the
percentage of leaf folder infestation.
• Early planting may enable plants to escape a high degree of
defoliation.
• Chemical Control
Many different kinds of insecticides including neem seed oil
(Saxena et al., 1980) have been used for leaffolder control

30. • Biological Control
• C. medinalis has a rich community of natural enemies in
insecticide-free ricefields.
• In China, Trichogramma japonicum and Apanteles cypris are
the most important egg and early larval instar parasitoids.
• In Sri Lanka, larval parasitization ranges from 38 to 70%. Five
parasitoids (four hymenopterans and a tachinid) are quite
common.

31. Rice Caseworm (Nymphula
Depunctalis)
• It is found in all the rice growing tracts of India
and assumes serious proportions in certain
season under swampy conditions.

32. • Tiny eggs are laid on leaves and leave sheath
in rows and batches.
• Under South Indian conditions a female lays
about 150 eggs which hatch in about a week.

33. • Young larvae feed by scrapping the
leave surface.
• The larva makes a cylindrical, tubular
case out of a portion of the leaf cut
and remains inside it, moving with
the case on the leaves.
• It feeds on the leaves actively and
becomes fully grown in about 20
days reaching a length of 10-12 mm.

35. • The larval stage pupates inside the last case.
• Before pupation the case is attached to the leaf sheath
above the water level and its both ends are plugged.
• The pupal period lasts for about a week, after which it
is converted into an adult insect.
• The pest is active during the monsoon and there may
be two or three broods in a season.
• The life cycle is completed in about 35-40 days.

36. • The caterpillars can breathe in aquatic
medium with the help of branched tubular
gills, hence the pest infestation is found in the
fields which are filled with water.
• Dispersal of larvae takes place by floating on
water. The case with larva drops in the water
and it paddles to reach another plant.

37. Control
• Cultural Method:
• 1. Draining out the stagnant water from the field is very
much effective in reducing the population of this pest.
• 2. Rotation of crop is advisable.
• 3. Destruction of weeds around the paddy fields
(weeds acts as alternate host of this pest).
• Chemical Method:
• 1. Spraying with DDT or dusting the crop with 10% BHC
or Carbaryl at the rate of 15-20 lbs/ acre is effective.
• 2 Spraying of “К-oil” or any other insecticides on the
water surface kill the caterpillars.

38. • Biological Method:
• 1. Introduction of Elasmus sps; Apalteles sps;
Bracon sps; Hormius sps is effective in
controlling the destruction caused by the larvae
because they paracitises the larval stages.
• 2. Introduction of Pediobius sps and Apsilops sps
is effective in controlling this pest because they
parasitises the pupal stage.

39. • Snails are useful predators of eggs of the rice
caseworm. The larvae are fed upon by the
hydrophilid and dytiscid water beetles.
Spiders, dragonflies, and birds eat the adults.

40. Rice Swarming Caterpillar
(Spodoptera mauritia)
• The adult is stoutly build dark-brown moth with
a Bloch of white on the fore wing. The males are
characterised by immense tuft of hairs on the
fore legs.

41. • The female moth is nocturnal in habit and
mate just 24 hours after their emergence.
• The eggs are laid in batches on various kinds of
wild grasses and paddy leaves.
• The number of eggs laid per batch may be 200-
300.

42. • The fully grown larva is smooth, cylindrical and
has a large pale colour with sub-dorsal and dorsal
stripes.
• The larvae feeds on rice leaves undergoes six
instars and grows to a length of 3.8 cms.
• It feeds during night and hides in soil in day time.
Pupation takes place in soil in an earthen cocoon.

44. • Plants attacked by caterpillars have
skeletonized leaves, shot holes, and
dieback stems. Commonly the entire
paddy crop dies within few days due to
swarming attack.

45. • The caterpillar feed at night on the leaves and defoliates
the plants completely.
• Generally they invade the transplanted plots in large
number in big swarm and devastate the whole plot
overnight like cattle’s do.
• After finishing the crop of one field the swarm marches
to another field in a regular army formation manner,
hence this pest is also called as “Army worm”.

46. Control
Cultural Method:
• 1. In case of severe attack of this pest, the entire
area should be isolated by trenching and the crop
should be ploughed up.
Chemical Method:
• 1. The field edges and bundh should be dusted
with Gammexine (0.025 %) at the rate of 15
lbs/acre in early stages.
• 2. Application of contact insecticide like BHC,
Carbaryl or Methyl Parathione controls the
caterpillars effectively.

47. Mechanical Method:
• 1. Collection of caterpillars with a hand net or
sweeping basket and their destruction.
Biological Method:
• 1. In the seedling stage, the nurseries may be
flooded with water. This will bring up the
caterpillars to the surface from where they
will be picked up by predator birds.
• 2. In small areas duck can be released in the
field which feed upon the larvae of this pest.

48. • Adults can eliminated by introducing Bolas spiders to
the fields.
• This spider has the ability to spray a pheromone
similar to female moth, to attract male moths.
• Moths traps like wing traps and unitraps can also
used to collect adults.