Light traps are commonly used tools in integrated pest management to monitor pest populations and determine seasonal patterns. They attract a wide variety of night-flying insects through the use of ultraviolet or fluorescent lights. While light traps provide useful information, pheromone traps have replaced them as they target specific pest species. Light traps are also used to manage some pest populations through mass trapping. Different light colors and wavelengths attract varying numbers of insect orders. Black lights and blue lights tend to attract the highest percentages of insects.

1. Role of light traps
Course: Ag. Ento 510- Integrated Pest
Management
Dineshkumar G. Dalvaniya
M.Sc.(Agri) In Entomology
1st Sem.-C.P.College of
Agriculture
S.D.A.U

2. How can a Crop be monitored
• A field crop is monitored to determine a pests
economic status or to determine whether a
natural enemy is at a level capable of
suppressing a pest's population density. So
identification of pests and beneficial insects is of
prime importance before any control operation is
executed.

3. • Monitoring tools like pheromone, light and sticky
traps can be advantageously used. Field
scouting adopting fixed plot survey or roving
survey should be taken from time to time to
monitor the crop in determining whether the pest
population attained ETLs.
• Which Products Form Part of The Ipm
Strategy
• Different monitoring tools like pheromone traps,
light traps, coloured sticky traps
• Preserved specimens of pests, natural enemies,
infested plant portions as identification tools

4. • Bird perches.
• Seed dressing chemicals and seed dressing
machines.
• Seeds of Resistant varieties.
• Ecofriendly insecticides like Neem products and
bio-fungicides like Trichoderma sp.
• Natural enemies like Trichogramma egg cards,
and microbial preparations of NPV & Bt.
• Soft and target specific pesticides.
• Bait preparations.
• Good plant protection equipment.
• Finally mostly farm based renewable resources
that can enhance the recycling phenomenon of
ecosystem should form part of IPM strategy

5. Light traps
• Light traps are mainly used for attracting moths
& other night flying insects which are attracted
towards the light. The insects are actively caught
or encouraged to enter a trap.
• The simplest light trap consists of a light on a
cable handling out side the building. Any bright
white or bluish light is suitable although mercury
bulb is the best. The effectiveness of the trap
can be enhanced if the lamp is positioned beside
a white wall or has a white sheet hung next to it.

6. • If electricity supply is not available then gas lamp
or paraffin vapour can be used. Light traps
should not be operated during rain because
water drops falling on the hot bulb will crack it if
it is not protected from rain water.
• Collections of a light trap provide significant clue
to the diversity of insects active at night
(Southwood and Henderson, 2000), their
respective affinity to different wavelengths of
light and to understand and predict how
populations function (Southwood and
Henderson, 2000).

7. • Such information, if properly documented, could
be put to multi-dimensional use by field-
researchers, such as, selection of light-traps for
attracting specific order of insects. Inspite of the
market being flooded with different models of
light traps with lightsources varying in their
intensity and wavelengths, no scientific data on
the trap collection, diversity, number and its
efficacy is available for ready use. Such a data
could shed light on the insects attracted to
specific range of light. In this regard, a
comparative analysis of different light trap
collections becomes mandatory in order to study
the efficacy of different wavelengths of light in
attracting insect of specific orders viz.,
Coleoptera (Sushil et al., 2004),

8. • Hemiptera (Rai and Khan, 2002; Manimaran and
Manickavasagam, 2000), Lepidoptera (Rose et
al., 2004), Hymenoptera and Diptera (Nair et al.,
2004). Further corelating this data with weather
parameters could help to predict the period of
maximum insect diversity and activity. In order to
make such information available, a complete
segregation of the individual trap collection over
a period of time on the basis of order and total
catch, and simultaneously corelating it with the
prevalent weather conditions becomes
necessary.

9. Using Lights to Attract Insects
• A great number of insect species are attracted to
light of various wavelength. Although different
species respond uniquely to specific portions of
the visible and nonvisible spectrum (as
perceived by humans), most traps or other
devices that rely on light to attract insects use
fluorescent bulbs or bulbs that emit ultraviolet
wavelengths (black lights).

10. • Hundreds of species of moths, beetles, flies, and
other insects, most of which are not pests, are
attracted to artificial light. They may fly to lights
throughout the night or only during certain hours.
Key pests that are attracted to light include the
European corn borer, codling moth, cabbage
looper, many cutworms and armyworms,
diamondback moth, sod webworm moths, peach
twig borer, several leaf roller moths, potato
leafhopper, bark beetles, carpet beetles, adults
of annual which grubs (Cyclocephala), house fly,
stable fly, and several mosquitos.)

11. • The mosquitoes Ochlerotatus (formerly Aedes)
triseriatus, Ochlerotatu (also formerly Aedes)
hendersoni, and Aedes albopictus are not
attracted to light, however.) Lights and light traps
are used with varying degrees of success in
monitoring populations and in mass trapping.
• Light traps similar to the one pictured in Figur
have been used for several decades to monitor
the presence of insects and to determine
seasonal patterns of pest density.

12. • But because pheromone traps are much more
specific (they catch only one or a few pest
species instead of many) and more convenient,
light traps are no longer as widely used.
Nonetheless, light traps provide useful
information about the timing, relative abundance,
or species composition of flights of European
corn borer, white grubs, sod webworms, and a
few other pests.

13. • A light trap used to survey nught-flying insects.
Most light traps use ultraviolet lamps and
capture a wide range of moths, beetles, and
other insects.Although numerous companies
market devices that use light as a lur for mass
trapping or removal trapping, using light to trap
out insect infestations is effective in only a few
specific situations. One widely used but very
ineffective application of light for insect control is
the placement of electrocutors or "bug zappers"
on lawns or patios. Such uses are ineffective for
at least two reasons.

14. • First, many insects that are attracted to the area
around the light traps (sometimes from
considerable distances) do not actually fly into
the trap. Instead, they remain nearby, actually
increasing the total number of insects in the
immediate area. Second, these lighted
electrocutors attract and kill a wide variety of
insects, the overwhelming majority of whi are not
pests. The nonpest species killed by such
devices include such beneficial insects as the
green lacewing, a predator that attacks a variety
of plant pests.

15. • Insect electrocutors can be effective in certain
indoor situations, especially in food warehouses,
processing plants, and restaurants. In these
facilities, electrocutors are placed in otherwise
dimly lit areas where their light is not visible from
outdoors. In such locations the trap does not lure
insects into the building, yet it does attract and
kill certain flies, moths, and beetles that are
pests of stored products or nuisances in food
production areas (see Gilbert, 1984).

16. • These traps can also be used somewhat
effectively in barns and stables to reduce some
fly and mosquito infestations. The efficiency of
electrocutors in such situations appears to be
low, however, and they must be positioned so
that they do not attract insects into a building
from outdoors.
• Although using electrocutor-light traps outdoors
is not efficient, the placement of outdoor lights
can be important. Positioning outdoor lights
away from entrances, windows, or other
openings reduces problems associated with
insect activity around the lights.

17. • Flood lights directed at loading docks, for
instance, do not lure insects into food
warehouses as so overhead lights mounted just
inside the loading dock door. Placing outdoor
lights several feet away from doors of homes
and apartments also concentrates insect activity
away from the sites where they cause the most
annoyance. In addition, yellow light bulbs attract
fewer insects that white incandescent lights or
fluorescent bulbs.

18. UV – LIGHT TRAP FOR GRAIN
STORAGE GODOWNS
• The UV light trap can be placed in food grain
storage godowns at 1.5 m above ground level,
preferably in places around warehouse corners,
as it has been observed that the insect tends to
move towards these places during the evening
hours. The trap can be operated during the night
hours.

19. • The light trap attracts stored product insects of
paddy like lesser grain borer, Rhyzopertha
dominica, red flour beetle, Tribolium castaneum
and saw toothed beetle, Oryzaephilus
surnamensis in large numbers. Psocids which
are of great nuisance in godowns are also
attracted in large numbers. Normally 2 numbers
of UV light trap per 60 x 20 m (L x B) godown
with 5 m height is suggested.

20. • The trap is ideal for use in godowns meant
for long term storage of grains, whenever
infested stocks arrive in godowns and
during post fumigation periods to trap the
resistant strains and left over insects to
prevent build up of the pest populations. In
godowns of frequent transactions the trap
can be used for monitoring.

21. • Management of white grub beetles
through light traps
• White grubs are the cosmopolitan insect pests of
agriculture, forest and pasture lands. The pest
causes severe economic loss in upland paddy,
finger millet, barnyard millet, maize, potato and
many other vegetables, fruits and fodder crops
in the hills of north-western Himalayan region,
where nearly 40 species of this phytophagous
pest were recorded.

22. • The beetles emerge from soil from May to
October. To combat the problem, VPKAS,
Almora, designed a user-friendly low cost (Rs
570), light trap for efficient mass trapping of
beetles, to reduce the population of white grubs
in soil. Deployment of 61 light traps in different
villages of Almora district on community basis
led to trapping of beetles 114,000 in Darima,
67,900 in chausali. 46,600 in Tipola-Tunakot,
88,900 in Daulaghat-Govindpur, 76,100 in
Manan and 31,400 in Bhagartola village from
June to September 2006.

23. • These light traps have become popular amongst
the farmers of this region, as a result of which
250 units of the trap were sold to the farmers
and other agencies Black Light for Monitoring
Helicoverpa zea (Boddie) (Lepidoptera:
Noctuidae) in Tomato The use of black light
traps to monitor adult tomato fruitworm,
Helicouerpa zea (Boddie), night activity is useful
for dictating the need for insecticide applications
for this insect on tomatoes (Lycopersicon
esculentum Miller)

24. • the need to relate black light trap catches
to oviposition for prediction of peak
populations in individual fields. They found
oviposition by H. zea to be more closely
related to the number of males rather than
females caught in black light traps.

25. INSECT ORIENTATION TO
VARIOUS COLOR LIGHTS IN
THE AGRICULTURAL
• This experiment was conducted at night
from 9.00 to 9.30 hours in the dark during
the year In order to cover diversity of
crops and forest vegetation All six lights
were arranged in line at 6 meter apart
from each other to let the insect to
orientate toward their most favorite light
color.

26. • All lights were simultaneously kept on for half an
hour and each of them was suitably projected on
white fabric screen. The fabric screens were
placed separately on stands almost one meter
high above ground to be visible from distance.
Plastic tub containing soapy water was placed
under each light to gather the attracted insects.
Soft brush was used to push the insects down in
tubes. At the end of experiment, insect material
of each tub was transferred to properly labeled
bottles (with color light, site, date and time etc.)
containing 10% alcohol and collection was
transferred to laboratory for identification In the
laboratory, contents of each collection bottle
were added in a large dish separately,

27. • exact number of insects was counted and each
of them was identified for respective insect
order. The same procedure was adopted for all
six collection bottles containing insect collection
gathered at each light color. Most of the insects
were identified by naked eye and field lens (10x)
was also used where needed to confirm the
diagnostic feature of smaller insects.

28. • Total numbers of insects caught at each colored
light. The experiments E1 and E2 were repeated
twice at each site. Total collection of insects per
light color was added up separately for each
experiment and then percentage of insects
attracted at each light spectrum was computed
to be tabulated in Table 1 .
• Finally the percentage of insects oriented
toward different light colors during both
experiments E1 and E2 were separately added
for respective light colors to compute the
cumulative percentage of insect attracted per
light color for more comprehensive and precise
results.

29. • According to the cumulative percentages of
insect collection gathered per light, the lowest
number of insects has been attracted at red
color light i.e. 2.3%. Back light attracted the
highest figure of 46.5% insects. Blue light was
rated to attract the second highest insect
numbers of 20.35% during both the light
experiments conducted at different sites. The
Chi-square calculation of 3814 is greater than
the chi-square critical value of 15.1 (d.f= 5,
p.=0.01). This is a highly significant difference
supporting the hypothesis that different
wavelengths of light will attract different number
and variety of insects

30. • Table 1: Percentage of insects attracted
at different colored light during night
hours in the field
Red 2.20%
Yellow 10.60%
Green 4.70%
White 18.00%
Black 42.10%
Blue 22.40%
Total insects 1020
caught