The document discusses common sampling techniques used to monitor insect pests. It describes different types of insect pests categorized based on their occurrence, including regular pests, occasional pests, seasonal pests, and more. Various sampling methods are also outlined, such as absolute sampling techniques like visual examination, quadrate sampling, and emergence traps. Relative sampling techniques including sweep nets, vacuum traps, pheromone traps, and visual traps are also summarized. The document provides details on different survey types and the objectives of pest surveillance.

1. COMMON
SAMPLING
TECHNIQUES
IN INSECT
PESTS
SUBMITTED TO: DR. BILAL RASOOL
SUBMITTED BY: ALI RAZA ISHAQ
ROLL NO: 94030
CLASS BS (8TH EVE) GCUF

2. COMMON SAMPLING
TECHNIQUES IN
INSECT PESTS

3. INTRODUCTION:
Pest ___ insect or other
organisms that cause
any damage to crop,
stored produce or
animal.
Pest that cause less
than 5% loss in yield,
are said to be
negligible.
Pest that cause 5-10%
loss in yield, are minor
pests
Pest that cause more
than 10% loss in yield,
are major pests.

4. CATEGORIES
OF INSECT
PESTS
There are
the
following
categories
of insect
pest:
Regular pests:
Occasional Pests:
Seasonal Pests:
Persistent Pests:
Sporadic Pests:
Epidemic Pests:
Endemic Pests:
Exotic Pests:

5. REGULAR
PESTS
• OCCUR MOST
FREQUENTLY (REGULARLY)
IN A CROP AND HAS CLOSE
ASSOCIATION WITH CROP.
• EXAMPLE’S
• :CHILLI THRIPS
• BRINJAL SHOOT
• FRUIT BORER
• SUGAR CANE BORERS.Chilli Thrips
This Photo by Unknown Author is licensed under CC BY-SA

6. OCCASIONAL
PESTS:
• THE PEST HAS CLOSE
ASSOCIATION WITH A CROP.
THEY OCCUR
OCCASIONALLY.
• FOR EXAMPLE
• RICE CASE WORM
• PADDY FLEA BEETLE
This Photo by Unknown Author is licensed under CC BY-SA-NC
Paddy Flea Beetle

7. SEASONAL PESTS
• RED HAIRY CATER PILLAR
OCCUR MOSTLY DURING A PART OF
THE YEAR, USUALLY THE INCIDENCE
IS GOVERNED BY CLIMATIC
CONDITIONS.
This Photo by Unknown Author is licensed under CC BY

8. PERSISTENT PESTS:
• OCCUR ON A CROP PERSISTENTLY.
• FOR EXAMPLE
• SCALES
• MEALY BUGS
• COCKROACHES
This Photo by Unknown Author is licensed under CC BY-SA

9. SPORADIC PESTS:
OCCASIONALLY CAUSING SERIOUS DAMAGE
EXAMPLE
PADDY LEAF ROLLER
This Photo by Unknown Author is licensed under CC
BY

10. EPIDEMIC PEST
EPIDEMIC MEANS ABUNDANCE, OUTBREAKS (SUDDEN
INCREASE IN LARGE NUMBERS) OF A PEST IN EACH AREA
AT GIVEN TIME.
This Photo by Unknown Author is licensed under CC
BY-SA

11. ENDEMIC PESTS:
ENDEMIC,MEAN BELONGING, OR
NATIVE TO, PREVALENT IN AN AREA.
ENDEMIC MEANS A PEST OCCURS
CONTINUOUSLY AND WITH
PREDICTABLE REGULARITY IN A
SPECIFIC AREA OR POPULATION
This Photo by Unknown Author is licensed under CC BY-SA
Citrus Black Fly

12. EXOTICE PESTS:
NON-NATIVE OR NON-INDIGENOUS.
PESTS NOT KNOWN TO OCCUR IN
THE STATE OR COUNTRY

13. PEST
MONITORIN
G
Monitoring phytophagous insects and their
natural enemies is a fundamental tool in
IPM - for taking management decision
Monitoring means estimation of changes in
insect distribution and abundance.
It also includes the information about
insects, life history or influence of biotic
and abiotic factors on pest population .

14. PEST
SURVEILLAN
CE
• SURVEILLANCE IS THE MONITORING OF THE BEHAVIOR, ACTIVITIES, OR
OTHER CHANGING INFORMATION, USUALLY OF PEOPLE, INSECTS, AND
PATHOGENS
• THE WORD SURVEILLANCE COMES FROM THE FRENCH WORD FOR
"WATCHING OVER".
• IT IS SYSTEMATIC MONITORING OF PEST POPULATION, DISPERSION, AND
DYNAMICS IN DIFFERENT CROP GROWTH PHASES TO FOREWARN THE
FARMERS TO TAKE UP TIMELY REQUIRED CROP PROTECTION MEASURES.
• PEST SURVEILLANCE CAN BE DONE USING THE
• LIGHT TRAPS
• PHEROMONE TRAPS
• FOOD TRAPS
• ATTRACTANTS
• PITFALL TRAPS (FOR SOIL INSECTS),
• FIELD SCOUTING

15. IMPORTANCE
AND
ADVANTAGE
S OF PEST
SURVEILLAN
CE:
• USEFUL FOR PEST FORECASTING
• HELP TO PLAN CROPPING PATTERN
• HELP TO PLAN PEST MANAGEMENT PROGRAMMERS'
• AIDS IN DEVELOPING MODELS, AND TO FIND-OUT
THE THUMB RULE MODELS.
• HELP IN APPLICATION OF INSECTICIDES (STAGE,
DOSE, TYPE ETC.)
• HELPS IN MAINTAINING STABILITY OF
AGROECOSYSTEM

16. COMPONEN
TS
REQUIRED
FOR PEST
SURVEILLAN
CE:
Identification of the Pest
Distribution pattern, and prevalence of the Pest
Severity of Pest
Levels of incidence of the pest
Losses due to pest incidence
Population dynamics
Weather parameters
Data on Natural enemies

17. BASIC
COMPONEN
TS FOR PEST
CONTROL
Three basic component
a) The level of incidence of the
pest species
b) The loss caused by the
incidence
c) The economic benefits, the
control will provide

18. PEST FORECASTING
Forecasting is the process of making
statements about events whose actual
outcomes (typically) have not yet been
observed.
A common place example might be
estimation of the expected value for some
variable of interest at some specified future
date. Prediction is a similar, but more
general term. Both might refer to formal
statistical methods employing time series,
cross-sectional or longitudinal data, or
alternatively to less formal judgmental
methods.

19. PEST
FORECASTIN
G
• PEST FORECASTING IS THE SYSTEMATIC
MONITORING OF PEST POPULATION, DISPERSION
AND DYNAMICS IN DIFFERENT CROP GROWTH
PHASES USING MODELS PREPARED BASED ON THE
PREVIOUS DATA, TO FOREWARN THE FARMERS TO
TAKE-UP TIMELY CROP PROTECTION MEASURES
NEEDED.
• PEST FORECASTING IS BASED ON THE MODELS
DEVELOPED USING THE PREVIOUS DATA POINTS
AND MANY ORGANIZATIONS ARE INVOLVED IN
FORECASTING OF PEST INCIDENCES AND
FOREWARNING ABOUT THE PEST OUTBREAKS.

20. USES OF
PEST
FORECAS
TING
A) PREDICTING PEST OUTBREAK WHICH NEEDS
CONTROL MEASURE
B) SUITABLE STAGE AT WHICH CONTROL
MEASURE GIVES MAXIMUM PROTECTION

21. TYPES OF PEST FORECASTING
• SHORT TERM FORECASTING
• BASED ON 1 OR 2 SEASONS
• THE PEST POPULATION IS
SAMPLED FROM A AREA
WITHIN A CROP USING
APPROPRIATE SAMPLING
TECHNIQUE AND THE
RELATIONSHIP IS ESTABLISHED
BETWEEN WEATHER DATA
AND PROGRESS IN PEST
INFESTATION.
• LONG TERM FORECASTING
• BASED ON EFFECT OF WEATHER
PARAMETERS ON PEST
• THE DATA ARE RECORDED OVER A
NUMBER OF YEARS ON WIDE
SEASONAL RANGE AND FROM
DIFFERENT AREAS. LONG-TERM
FORECASTING IS BASED ON
KNOWLEDGE OF THE MAJOR ASPECTS
OF THE PEST INSECT’S LIFE- CYCLE,
AND OF HOW IT IS REGULATED.

22. • TO KNOW EXISTING AND NEW PEST SPECIES
• TO ASSESS PEST POPULATION AND DAMAGE
AT DIFFERENT GROWTH STAGE OF CROP
• TO STUDY THE INFLUENCE OF WEATHER
PARAMETERS ON PEST
• TO STUDY CHANGING PEST STATUS (MINOR
TO MAJOR)
• TO ASSESS NATURAL ENEMIES AND THEIR
INFLUENCE ON PESTS’ EFFECT OF NEW
CROPPING PATTERN AND VARIETIES ON PEST
OBJECTIVES OF PEST
SURVEILLANCE

23. SURVEY
CONDUCTED TO
STUDY THE
ABUNDANCE OF A
PEST SPECIES

24. TYPES OF
SURVEY: • Roving survey
• Fixed plot survey
There are two types of survey

25. ROVING
SURVEY
• ASSESSMENT OF PEST
POPULATION/DAMAGE
FROM RANDOMLY
SELECTED SPOTS
REPRESENTING LARGER
AREA. LARGE AREA
SURVEYED IN SHORT
PERIOD. PROVIDES
INFORMATION ON PEST
LEVEL OVER LARGE AREA

26. FIXED PLOT SURVEY
ASSESSMENT OF PEST POPULATION/DAMAGE FROM A
FIXED PLOT SELECTED IN A FIELD. THE DATA ON PEST
POPULATION/DAMAGE RECORDED PERIODIC FROM
SOWING TILL HARVEST.

27. QUALITATIVE
SURVEY
IT IS
USEFUL
FOR
DETECTIO
N OF PEST

28. QUANTITATIV
E SURVEY
IT IS
USEFUL
FOR
ENUMERA
TION OF
PEST.

29. SAMPLING TECHNIQUES

30. ABSOLUTE SAMPLING
• TO COUNT ALL THE PESTS OCCURRING IN A PLOT. ABSOLUTE METHODS
ESTIMATE DENSITY FROM PRECISE AREA; USED TO COMPARE DENSITIES BASED
ON AREA. POPULATION INDEX MEASURES PRODUCT OR EFFECT OF A
POPULATION.

31. • EXAMPLES:
• VISUAL EXAMINATION
• QUADRATE SAMPLING
• SUCTION SAMPLING
• ENCLOSURE DEVICES
• EXTRACTION
• EMERGENCE
• AERIAL NETS

32. VISUAL
EXAMINATION
• USED FOR DETECTING HOUSEHOLD AND
STRUCTURAL PESTS, AND IMPORTANT WHERE
THE INSECTS THAT MIGHT BE ENCOUNTERED
ARE UNKNOWN, CRYPTIC, OR VARIABLE
• DOGS AND ELECTRONIC DETECTOR ARE
SOMETIMES USED TO FIND INVISIBLE
TUNNELING LIKE THAT WHICH OCCURRED IN
THIS WALL BASEBOARD, FOLLOWED BY VISUAL
CONFIRMATION.
VISUAL EXAMINATION IS OFTEN AN
EFFECTIVE, IF TIME CONSUMING, WAY
TO SAMPLE ARTHROPODS

33. QUADRATE
SAMPLING
• A MITE BRUSHING MACHINE BRUSHES ITEMS
FROM THE SURFACE OF LEAVES, PROPELLING
THEM DOWNWARD ONTO A THIN FILM OF OIL
THAT COATS A GLASS PLATE. THUS, IT IS
POSSIBLE TO DETERMINE THE NUMBER OF
MITES PER LEAF.
QUADRATE SAMPLING DELINEATES
AN EXACT AREA OF SAMPLING,
THOUGH THE AREA NEED NOT
REALLY BE 4-SIDED.

34. LIVE TRAPS
• IT IS THE COMBINATION OF ANIMAL
POPULATION, DISEASE INCIDENCE AND INSECT
VECTOR POPULATION THAT DETERMINES THE
THREAT TO HUMANS.
ARE USED TO CAPTURE SMALL
ANIMALS SUCH AS RODENTS, WHICH
THEN CAN BE EXAMINED FOR BOTH
TICK AND FLEA VECTORS

35. EMERGENCE TRAPS
• USUALLY SUCH TRAPS TAKE ADVANTAGE OF
THE INSECT’S TENDENCY TO MOVE TO LIGHT
AND HAVE A CAPTURING OR KILLING
MECHANISM AT THE TOP OF THE TRAP.
OFTEN ARE USED TO CAPTURE
INSECTS THAT LIVE BELOWGROUND
OR UNDER WATER

36. RELATIVE
SAMPLIN
G
• TO MEASURE PEST IN TERMS OF SOME VALUES
WHICH CAN BE COMPARED OVER TIME AND
SPACE E.G. LIGHT TRAP CATCH, PHEROMONE
TRAP. RELATIVE METHODS ESTIMATE DENSITY
WITHOUT STRICT REGARD TO AREA SAMPLED;
USED TO COMPARE AMONG EFFORTS BASED ON
EFFORT.
.

37. EXAMPLES:
• SWEEP NET
• VACUUM TRAP
• TIMED COUNTS
• TRAPS
• VISUAL
• CHEMICAL
• INTERCEPTION
A PHEROMONE-BAITED TRAP LIKE THIS
CAPTURES MOTHS WHEN THEY FLY AND CRAWL
UPWARDS AND ARE CAPTURED IN THE
CONTAINER ON TOP

38. SWEEP NET
• SWEEPING WITH A NET IS
A VERY COMMON AND
INEXPENSIVE METHOD OF
SAMPLING. FLIGHT TRAPS
COST SUBSTANTIALLY MORE
AND ARE LIMITED TO
FLYING INSECTS.
This Photo by Unknown Author is licensed under CC BY

39. VACUUM TRAP
• VARIOUS VACUUM SAMPLERS ARE USED AND
ARE OFTEN CALLED “DVACS” AFTER THE
ORIGINAL MODEL. THEY ARE EFFICIENT, BUT
COSTLY AND NOISY TO OPERATE. VACUUM
SAMPLER IS USED TO VACUUM THE CONTENTS
OF A BOX PLACED OVER SHRUBS. THIS
EFFECTIVELY CONVERTS ITS OPERATION FROM
A RELATIVE TO AN ABSOLUTE SAMPLING
PROCEDURE.
This Photo by Unknown Author is licensed under CC BY-SA-NC

40. TRAPS

41. Traps are widely used for insect sampling and
monitoring.
Light traps were more popular before the advent of
pheromones. They have the advantage, and
disadvantage, of being non-selective.
They can be operated off battery or household
current. Here the battery is being recharged by a solar
panel.

42. VISUAL TRAPS
• A FRUIT MODEL MAKES A GOOD VISUAL TRAP,
SUCH AS THIS GRAPEFRUIT MODEL. WHEN
COVERED WITH ADHESIVE,
• IT ALLOWS ESTIMATION OF ADULT NUMBERS.
URBAN PEST CONTROL COMPANIES OFTEN USE
STICKY TRAPS TO SAMPLE FOR INSECT PESTS IN
COMMERCIAL ESTABLISHMENTS AND SCHOOLS.
• THEY ARE NOT VISUALLY ATTRACTIVE (SOME
WOULD DESCRIBE THEM AS DISGUSTING), SO THEY
MUST BE PLACED IN OUT-OF-THE-WAY PLACES,
SUCH AS STOREROOMS.
• INSECTS STUCK IN ADHESIVE ARE MESSY AND CAN
BE DIFFICULT TO REMOVE AND IDENTIFY. ALSO,
SUCH TRAPS MAY NOT BE SELECTIVE
This Photo by Unknown Author is licensed under CC BY-SA

43. BUCKET TRAP
• THE BUCKET TRAP AND
WING TRAP INTRODUCE
SELECTIVITY BY USING
PHEROMONES AS LURES.
This Photo by Unknown Author is licensed under CC BY-NC-ND

44. PHEROMONE
TRAPS
• PHEROMONE TRAPS ARE POPULAR
BECAUSE THEY PROVIDE
SPECIFICITY, ARE COMMERCIALLY
AVAILABLE, AND CAN BE USED
UNDER A VARIETY OF
CIRCUMSTANCES.
• THOUGH PHEROMONE TRAPS
USUALLY RELY ON ADHESIVE FOR
INSECT RETENTION, THIS IS NOT
ALWAYS OPTIMAL
This Photo by Unknown Author is licensed under CC BY-NC

45. MOSQUITO
TRAP
• QUITE VARIED, BUT
OFTEN INVOLVE THE USE OF
DRY ICE AS A SOURCE OF
CARBON DIOXIDE, AND A
SMALL FAN TO BLOW THE
MOSQUITOES INTO A
RECEPTACLE.
This Photo by Unknown Author is licensed under CC BY-SA

46. FLIGHT TRAP
• FLIGHT TRAP, CALLED A MALAISE
TRAP, IS AN EXAMPLE OF AN
INTERCEPTION TRAP.
• THERE IS NO ACTIVE ELEMENT
TO THE TRAP, THEY ARE FLYING
INSECTS ARE INTERCEPTED,
CRAWL UPWARDS, AND ARE
CAPTURED IN A JAR.
• THE OTHER COMMON
INTERCEPTION TECHNIQUE IS A
TRANSPARENT PANE OF PLASTIC
OR GLASS WHICH INTERRUPTS
FLIGHT. INSECTS ARE CAPTURED
ON ADHESIVE OR FALL INTO A
RESERVOIR OR RECEPTACLE.
This Photo by Unknown Author is licensed under CC BY-SA

47. SAMPLING PLANS

48. FOUR
MAJOR
TYPES OF
PLANS
Fixed sample size Sampling
Sequential Sampling
Variable-intensity Sampling
Binomial Sampling

49. FIXED
SAMPLE
SIZE
• MOST COMMON APPROACH (E.G., “10”) THOUGH
OPTIMAL SIZE CAN BE CALCULATED. OPTIMAL
SAMPLE SIZE DECREASES WITH POPULATION
DENSITY.
• SHOULD BE ABLE TO GET BY WITH FEWER SAMPLES
AT HIGH DENSITY.

50. OPTIMAL
SAMPLE
SIZE
• THERE ARE VARIOUS MEANS TO CALCULATE THE
OPTIMAL SAMPLE SIZE IF YOU ELECT TO USE A
FIXED SAMPLE.
• YOU WANT TO BE SURE THAT YOU CAN BE SURE
THAT YOU OBTAIN AN ACCURATE ASSESSMENT
OF THE POPULATION.
• N = S2 / E X
• WHERE N IS THE NUMBER OF SAMPLES, S IS THE
STANDARD DEVIATION, E IS THE PREDETERMINED
STANDARD ERROR AS A DECIMAL OF THE MEAN
(IN THIS CASE 0.05), X IS THE MEAN.

51. SEQUENTI
AL
SAMPLING
:
• VARIABLE NUMBER OF SAMPLES TAKEN. SAMPLE
UNTIL THE POPULATION CAN BE CLASSIFIED (E.G.,
NO THREAT OR CONTROL NEEDED).
• MORE SAMPLING AT INTERMEDIATE LEVELS AND
EFFICIENT SAMPLING METHOD.

52. BINOMIAL
SAMPLIN
G
• RELATIONSHIP BETWEEN % OF INFESTED SAMPLING
UNITS (E.G. LEAVES) AT DIFFERENT PEST
DENSITIES. TALLY NUMBER OF LEAVES INFESTED
INSTEAD OF COUNTING PESTS. ESTIMATES
UNRELIABLE WHEN INFESTATIONS ARE HIGH (≥
80%)
RECORDS PRESENCE OR ABSENCE; PROPORTION
INFESTED OR DAMAGED
DOES NOT TABULATE NUMBER OF INSECTS

53. METHODS OF
SAMPLING

54. 1. IN SITU COUNTS
• VISUAL OBSERVATION ON NUMBER OF INSECTS ON PLANT CANOPY (EITHER
ENTIRE PLOT OR RANDOMLY SELECTED PLOT).
• COUNTS OF INSECT/MITES OR DAMAGE DIRECTLY ON LEAVES, STEMS, FRUIT,
ROOT. APHIDS, SCALE INSECTS’ MITES, LEAF MINERS, SMALL CATERPILLARS,
LEAF HOPPERS, IMMATURE PSYLLA. 10X-20X HAND LENS USEFUL FOR THIS
METHOD.

55. KNOCK DOWN AND NETTING
• COLLECTING INSECTS FROM AN AREA
BY REMOVING FROM CROP AND
(SUDDEN TRAP) COUNTING (JARRING)
• IN THIS TECHNIQUE, USE OF SWEEP
NET FOR HOPPERS, ODONATES,
GRASSHOPPER

56. NOR COTISED COLLECTION
• QUICK MOVING INSECTS ANAESTHETIZED AND COUNTER

57. STAGE OF
SAMPLING
• USUALLY MOST INJURIOUS STAGE COUNTED
• SOMETIMES EGG MASSES COUNTED PRACTICAL
CONSIDERATIONS
• HOPPERS - NYMPHS AND ADULT COUNTED

58. SAMPLE
SIZE
Differs with nature of
pest and crop
Parger sample size
gives accurate results

59. DECISION MAKING
Population or damage
assessed from the crop
Compared with ETL and
EIL
When pest level crosses
ETL, control measure
must be taken to
prevent pest from
reducing EIL.

60. ECONOMI
C INJURY
LEVEL
• DEFINED AS THE LOWEST POPULATION DENSITY
THAT WILL CAUSE ECONOMIC DAMAGE. IT CAN
ALSO BE DEFINED AS A CRITICAL DENSITY WHERE
THE LOSS CAUSED BY THE PEST EQUALS THE COST
OF CONTROL MEASURE.

61. EIL
FORMULA
• EIL = ____C________
V X I X D X K
EIL = ECONOMIC INJURY LEVEL IN INSECTS/PRODUCTION (OR)
INSECTS/HA
C = COST OF MANAGEMENT ACTIVITY PER UNIT OF PRODUCTION
(RS. /HA)
V = MARKET VALUE PER UNIT OF YIELD OR PRODUCT (RS. /TONNE)
I = CROP INJURY PER INSECT (PER CENT DEFOLIATION/INSECT)
D = DAMAGE OR YIELD LOSS PER UNIT OF INJURY (TONNE
LOSS/% DEFOLIATION)
K = PROPORTIONATE REDUCTION IN INJURY FROM PESTICIDE
USE

62. MONITORIN
G DEGREE
DAYS
• DETERMINE BEST TIME TO SAMPLE FOR OR
CONTROL INSECTS/ MITES PARTICULAR INSECT/
MITE GROWTH STAGE. PREDICTS INSECT
DEVELOPMENT BY ACCUMULATING HEAT UNITS
(DEGREE DAYS).

63. MONITORIN
G DEGREE
DAYS
Biofix:
When to begin accumulating degree days Calendar date or biological
event (1st or peak flight).
Threshold temperatures:
Lower threshold: no development below this
Upper threshold: no development above this
Mean daily temperature: Tmax - Tmin /2

64. SAMPLING
TOOLS:
Clipboard
Keep all the
scouting forms
and field maps in
one place.
Field maps
Jot notes, location
pest problems and
record
observations
Scouting forms
Record sampling
monitoring data,
field history.
Hand lens
See and correctly
identify pests, 10-
20x Pencils Carry a
spare

65. SAMPLING
TOOLS
Collection bags and vials –Send pest /damage samples to others
Traps/ trap parts (lures) –There’s always a broken trap
Camera –Send pest /damage photo to others for ID
References –field guides, fact sheets, pictures of pests/damage
GPS unit –relocate sample sites accurately
Pocket knife
Cutting shoots, scraping at trunks skinning berries.
Shovel /sturdy trowel –digging soil

66. CONCLUSIO
N
• IN SUMMARY, THE WIDESPREAD USE OF
INSECTICIDES IS INEFFECTIVE AND ECONOMICALLY
WASTEFUL IN THE LONG RUN. MANY INSECTICIDES
DO IN FACT ACCOMPLISH THE INTENDED TASK OF
CONTROLLING PEST POPULATIONS. HOWEVER,
THEIR DETRIMENTAL HEALTH AND ENVIRONMENTAL
EFFECTS MAKE THEM AN INADEQUATE LONG-TERM
SOLUTION. IN ADDITION, MOST SYNTHETIC AND
NATURAL PESTICIDES ARE SUSCEPTIBLE TO
INEFFECTIVENESS DUE TO RESISTANCE BUILDUP IN
INSECTS. THUS, THE ONLY VIABLE SOLUTION FOR
THE FUTURE IS INTEGRATED PEST MANAGEMENT.
THE ECONOMIC BENEFITS AND REDUCED SOCIAL
COSTS OF THESE SYSTEMS PRESENT A LOGICAL
ANSWER TO THE PEST CONTROL PROBLEM.

67. This Photo by Unknown Author is licensed under CC BY-NC