Pest Management

Pest Management

Civilization has been combating insects 

and other pests throughout history. 

Records contain many examples of how 

pests have had major impacts on humans. 

Probably the most infamous was the 

Black Plague of Europe, when millions 

of people died in the 14th century from 

a mysterious scourge. Only centuries 

later was it determined that a bacterial 

disease spread by rat fleas was the cause. 

Rat fleas became infected with bacteria 

while feeding on diseased rats. When 

rats were unavailable as a food source, 

the fleas sought other warm-blooded 

hosts, often humans. Today this disease, 

known as bubonic plague, can be treated 

if properly diagnosed. Controlling rats 

and other rodents and fleas can reduce 

disease incidence. 

One historical occurrence that 

directly influenced the population of 

the United States was the destruction 

After studying this chapter, you should:

• Know the main groups of common pests.

• Know how to use pest control references and resources to 

help identify pests and recognize symptoms and damage.

• Understand various pest control procedures.

• Understand integrated pest management (IPM) control options 

(e.g., biological, cultural, mechanical, sanitation, chemical controls).

• Understand when preventive pest control is required.

• Understand how pest population levels trigger control procedures.

• Anticipate effects on pest, hosts, and natural enemies of relevant 

environmental variables that influence pest populations (e.g., 

weather, geographic barriers, cultural practices, nutrient supply).

• Understand probable causes of non-effective pest control (e.g., 

incorrect pest identification, incorrect dosage, incorrect application 

timing, incorrect pesticide product).

• Know how to plan pest control strategies that minimize the 

development of pesticide resistance (e.g., rotation of pesticide types 

with different modes of action, application of pesticides that do not 

leave persistent residues, application of pesticides at below-label 

amounts).

LEARNING OBJECTIVES

1

Above lady beetle photo: Marlin E. 

Rice, Ph.D., Iowa State University

CHAPTER 1
2 CHAPTER 1

of Ireland’s potato crop by a pest in 

the 19th century. A fungal disease 

called late blight essentially eliminated 

potatoes, the staple food crop. Potatoes 

not destroyed in the field rotted in 

storage during the winter. Thousands 

of Irish starved in the resulting famine, 

and more than a million migrated to 

the United States. Late blight continues 

to be a major problem of potatoes, but 

today it is managed through the use 

of resistant cultivars, proper sanitation 

practices, and fungicides.

The above examples illustrate the 

potential enormity and complexity 

of pest problems. But what is a pest? 

Webster's Dictionary defines a pest as 

“any destructive or troublesome insect, 

small animal, weed, etc.” Many insects, 

pathogens (disease-causing organisms), 

weeds, mollusks (slugs and snails), 

fish, birds, and a variety of mammals, 

from rats to deer, are competitors for 

our livestock and crops. In addition, 

some pests destroy buildings and other 

structures and reduce the aesthetic and 

recreational value of the landscape. The 

competition between humans and pests 

has evolved over time, and so have the 

methods of control.

Mystery surrounded the causes of crop 

failures and human and animal diseases 

for many centuries. The first pest 

control measures were crude—weeds 

were pulled, rats were clubbed, and 

beetles were plucked from foliage. The 

earliest use of chemicals as pesticides 

dates back to 2500 B.C., when sulfur 

was burned to control insects and mites. 

Through the years, experimentation 

and good fortune led to the recognition 

of additional chemicals with pesticidal 

activity. Early plant-derived insecticides included hellebore to control body 

lice, nicotine to control aphids, and 

pyrethrins to control a wide variety of 

insects. Lead arsenate was first used 

in 1892 as an orchard spray. In 

France during the late 19th 

century, a mixture of lime 

and copper sulfate was 

sprayed on grapevines 

to deter passers-by from 

picking the grapes. 

The farmer found the 

mixture also controlled 

downy mildew, a serious 

fungal disease of grapes. 

Later named Bordeaux 

mixture, it remains a widely 

used fungicide worldwide. 

Until the 1940s, pest control 

chemicals were derived from plants and 

inorganic compounds. During World 

War II, DDT, a synthetic chemical, 

played a very important role, saving 

Allied soldiers from insect-transmitted 

diseases. DDT was hailed as the insecticide to solve all insect problems. 

The introduction of countless other 

synthetic organic pesticides followed. 

These synthetic products launched 

the modern-day chemical industry and 

began a new era in pest control. Given 

significant success at a relatively low 

cost, pesticides became the primary 

means of pest control. They provided 

season-long crop protection against 

pests and complemented the benefits of 

fertilizers and other production practices. The success of modern pesticides, 

particularly in agriculture and human 

health, encouraged widespread acceptance and eventual reliance on them.

In recent years, however, some 

drawbacks of heavy dependence on 

pesticides have become increasingly 

apparent. One of the most disturbing is 

the development of pest resistance to 

pesticides. Since the resistance of the 

San Jose scale to lime sulfur was recognized in 1908, hundreds of insects have 

become resistant to one or more pesticides worldwide. Pesticide resistance 

also has arisen in more than 50 weeds 

and many plant pathogens. A dramatic 

example is the Colorado potato beetle 

in the eastern United States. This insect 

pest has developed resistance to every 

major group of insecticides, making 

control with chemicals difficult, if not 

impossible, to achieve.

Growing concerns about the 

environmental and health hazards assoPEST CONTROL OVER THE YEARS

Early agricultural 

bulletins on pesticide 

application.

C. Randall, MSU
Pest Management

ciated with pesticides have also become 

significant factors challenging pesticide 

use. In 1962, Rachel Carson published 

Silent Spring, a book that examined 

pesticides and their effects on the 

environment. DDT and other chlorinated hydrocarbons were her primary 

concern because of their stability and 

persistence in the environment. Their 

long residual activity was a major factor 

contributing to their effectiveness, but 

a negative effect was their ability to 

accumulate in the fatty tissue of some 

animals (bioaccumulation). In certain 

situations, biomagnification of the 

insecticides occurred. Biomagnification 

is the process whereby some organisms 

accumulate chemical residues in higher 

concentrations than those found in the 

organisms they consume. Ecologists 

refer to a food chain as the sequence 

of animals feeding in the natural environment. A particular plant, animal, or 

microorganism is eaten by an animal, 

which is in turn eaten by another animal. 

At each succeeding level, an animal normally eats a number of individuals from 

the previous level. Figure 1.1 depicts 

how biomagnification of a pesticide can 

occur in a food chain. Organisms with 

pesticides in their tissues are eaten by 

fish, which are in turn eaten by birds. 

The birds at the top of the food chain 

accumulate the highest concentration 

of pesticide residues. 

Since the publication of Silent 

Spring, the United States has experienced a level of environmental awareness 

and interest second to no other period 

in history. The U.S. Environmental 

Protection Agency (EPA) was created 

in 1970 with a mandate from Congress. 

Its task was then, and remains today, 

to implement by regulation the laws 

passed by Congress to protect the 

environment and the health of humans 

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Figure 1.1 Biomagnification in the Food Chain

3

Adapted from Penn. State Pesticide Education Manual
CHAPTER 1

and other animals. Since the 1972 EPA 

ban on DDT use in the United States, 

regulatory action has been taken against 

many chemicals, including pesticides, 

thought to pose significant environmental and health hazards. Public 

concern has led to stringent regulation 

of pesticides and changes in the types 

of pesticides used.

Pests are organisms that cause 

problems in various ways. Some 

compete with people for food or fiber. 

Others interfere with the raising of 

crops, livestock, or poultry. Certain 

types of pests damage property and 

personal belongings or disfigure 

ornamental plantings. Others 

transmit or cause plant, animal, or 

human diseases.

Before trying to control a pest, 

you need to identify it. Be certain any 

injury or observed damage is actually 

due to the identified pest and not some 

other cause. Once you have identified 

the pest and confirmed that it is causing 

damage, become familiar with its life 

cycle, growth, and reproductive habits. 

Then, use this information to form your 

pest control plans. Misidentification 

and lack of information about a pest 

could cause you to choose the wrong 

control method or apply the control 

at the wrong time. These are the 

most frequent causes of pest control 

failure.

In addition, some plants are 

damaged by non-living agents. These 

include such things as weather extremes, 

air pollutants, road salt, and inadequate 

or excessive fertilization. Sometimes 

this damage is mistaken for that caused 

by living pests.

Ways to Identify Pests

Identify a pest by using the guidelines included in this chapter and then 

consulting reference materials such as 

identification books, Extension bulletins, and field guides that contain 

pictures and biological information 

on the pest. Another option is to have 

pests examined and identified by pest 

management specialists. When having 

pests identified, always collect several 

specimens. Have plastic bags, vials, or 

other suitable containers available when 

collecting samples in the field. For plant 

diseases, submit undamaged specimens, 

such as healthy foliage, along with the 

damaged foliage. For insects and their 

relatives, kill them first and send them 

to the specialist in a manner that will 

not damage body parts that aid in their 

identification. For weed/plant samples, 

it is best to submit whole plants, 

including roots, vegetative structures, 

and flowers, if possible. Plants may be 

pressed flat between paper or cardboard 

to prevent leaf crinkling or placed 

in plastic bags. Be sure to include the 

location and date of the collection.

The difficulty in identifying certain 

insects and most mites, nematodes, and 

plant pathogens in the field is their 

small size. Accurate identification 

requires the use of a hand lens or microscope, special tests, or careful analysis 

of damage. Often the pest’s host (the 

animal or plant on which an organism 

lives) and location are important 

to making positive identifications. 

Information on the environmental 

conditions where you collect pests and 

the time of year of collection provides 

clues to the pest’s identity.

The Four Main Groups of Pests

• Weeds (undesirable plants).

• Invertebrates (insects, mites,

ticks, spiders, snails, and slugs).

• Disease agents or pathogens

(bacteria, viruses, fungi,

nematodes [roundworms],

mycoplasmas [parasitic

microorganisms], and other

microorganisms).

• Vertebrates (birds, reptiles,

amphibians, fish, and rodents

and other mammals).

PEST RECOGNITION

Invertebrate pest.

Weed pest.

Disease pest.

4

Larry Schulze, University of Nebraska
Pest Management

Pest species may have different 

physical forms depending on their stage 

in their life cycles or the time of year. 

Weed seedlings, for example, often do 

not resemble the mature plant. Many 

insect species undergo changes in 

appearance as they develop from eggs 

through immature stages (nymph, larva, 

pupa) to the adult form.

Characteristic Damage

Pests may leave signs of their 

presence or damage that help you 

determine what they are. Birds and 

rodents build nests that are often characteristic to each species. The type 

of feeding damage helps you identify 

many insects. Rodents and some other 

mammals dig distinctive burrows in 

the ground and often leave identifying 

gnaw marks on tree trunks or other 

objects. Sometimes trails in grass 

or tracks in dirt are helpful clues 

to rodent identification. Insect and 

rodent fecal materials also are distinctive and important identification 

aids. Weeds may have unique flowers, 

seeds, or fruits, or unusual growth 

habits. Fungi and other pathogens 

often cause specific types of damage, 

deformation, or color changes in host 

tissues.

Once a pest problem is anticipated or 

identified, you can begin planning your 

pest management program. You must 

know what management methods are 

available and the benefits and limitations of each. Select methods that are the 

most effective and the least harmful to 

people and the environment. Whenever 

possible, combine the use of several 

compatible methods into an integrated 

pest management (IPM) program, and 

target the pest at the most susceptible 

stage for control.

Natural controls are the measures 

that check or destroy pests without 

depending on humans for their continuance or success. Natural controls 

include climatic factors such as wind, 

temperature, sunshine, and rain. 

Topographic features such as rivers, 

lakes, and mountains can influence 

pest movement. Naturally occurring 

predators, parasites, and pathogens can 

regulate pest populations.

When natural controls have not 

held pests in check, humans must 

intervene and apply pest management 

controls. Applied controls include biological, mechanical, cultural, physical, 

genetic, chemical, and regulatory 

methods. 

Biological Control

Most pests have natural enemies 

that control or suppress them effectively 

in some situations. Natural enemies, 

including pathogens, are being used 

successfully as biological control agents 

to manage certain insect, mite, fungal, 

fish, and weed pests.

Biological control is often directed 

against pests that are not native to a 

geographical area. Introduced pests are 

often problems in their new location 

because they lack natural enemies to 

help control them. Biological control 

involves locating the native home of 

an introduced pest and finding suitable 

natural enemies there. After extensive 

testing and evaluation, selected natural 

enemies are imported, reared, and 

released. If successful, the introduced 

natural enemies become established 

within large areas and effectively lower

Pest Management Methods

Natural controls

Applied controls

• Biological control

• Mechanical control

• Cultural control

• Physical/environmental

modification

•  Host resistance or genetic

control

• Chemical control

•  Regulatory Methods

Vertebrate pest.

PEST management methods

5

Lee Karney, USFWS
CHAPTER 1

target pest populations for long periods 

of time with no further need for intervention. The process is complicated 

because it is often difficult to locate the 

native home of some pests, and natural 

enemies cannot be released until it is 

proven that they will not become pests 

themselves. Laws have been enacted 

that strictly control the importation 

of all organisms, including biological 

control agents, into the United States. 

Other countries have similar restrictions.

Biological control also involves the 

mass release of large numbers of natural 

enemies into fields, orchards, greenhouses, or other locations to control 

specific pests. This method usually 

does not have long-term results, so 

these natural enemies must be released 

periodically. Several natural enemies 

are reared or cultured commercially. 

Predatory mites are used to control 

plant-feeding spider mites. Parasitic 

wasps and lacewings are used to control 

various insect pests. Nematodes and 

fungi are being studied as biological 

control agents for certain weeds and 

some insects. General predators such 

as praying mantids and lady beetles are 

sold with claims made for biological 

control. In many cases, however, their 

effectiveness has not been established.

 Maintaining populations of 

natural enemies by avoiding damaging 

cultural practices or the indiscriminate 

use of pesticides can be one of 

the most economical means 

of control. If pesticides 

are part of your control 

program, select types 

that are known to be 

less toxic to natural 

enemies or, if recommended, apply 

pesticides at lowerthan-label rates to 

avoid harming natural 

enemies. Sometimes it is 

possible to modify certain 

parts of the environment, such 

as by planting crops or ground 

covers, to maintain or enhance natural 

enemies.

Mechanical Control

Mechanical control involves the 

use of devices, machines, and other 

physical methods to control pests or 

alter their environment. Traps, screens, 

barriers, fences, and nets are examples 

of devices used to prevent pest activity 

or remove pests from an area.

Cultivation

Cultivation is one of the most 

important methods of controlling 

weeds. It is also used for some insects 

and other soil-inhabiting pests. 

Mechanical devices such as plows, 

disks, mowers, cultivators, and bed 

conditioners physically destroy weeds 

or control their growth and disrupt soil 

conditions suitable for the survival of 

some microorganisms and insects.

Exclusion

Exclusion is a mechanical control 

technique that consists of using barriers to prevent pests from getting into 

an area. Window screens, for example, 

exclude flies, mosquitoes, and other 

flying insects. Patching or sealing cracks, 

crevices, and other small openings in 

buildings can exclude insects, rodents, 

bats, birds, or other pests. Fences and 

ditches make effective barriers against 

many vertebrate pests. Wire or cloth 

mesh excludes birds from fruit trees. 

Sticky material painted onto tree 

trunks, posts, wires, and other objects 

prevents crawling insects from crossing.

Parasitic wasps may be 

used as biological control 

agents.

6

Scott Bauer, USDA ARS
Pest Management

Trapping

Traps physically catch pests within 

an area or building. Several types of 

traps are commonly used. Some kill 

animals that come in contact with them; 

others snare animals so they can then be 

relocated or destroyed. Traps are either 

mechanical devices or sticky surfaces.

Cultural Control

The goal of cultural control is to 

alter the environment, the condition of 

the host plant or site, or the behavior 

of the pest to prevent or suppress an 

infestation. It disrupts the normal relationship between the pest and the host 

plant or site and makes the pest less 

likely to survive, grow, or reproduce. 

Cultural practices and sanitation are 

two examples of cultural control.

Cultural Practices

Many cultural practices influence 

the survival of pests. In turf, mowing, 

irrigation, aeration, and fertilization are 

all important ways of producing healthy 

turf and preventing pest buildup 

and damage. In agricultural crops, 

selection of crop plant varieties, timing 

of planting and harvesting, irrigation 

management and timing, crop rotation, 

and use of trap crops help reduce 

populations of weeds, microorganisms, 

insects, mites, and other pests. Weeds 

also can be managed by mulching (with 

plastic, straw, shredded bark, or wood 

chips) and by using cover crops.

Sanitation

Sanitation, or source 

r e d u c t i o n , i n v o l v e s 

eliminating food, water, 

shelter, or other necessities 

important to the pest’s survival. In crop production, 

sanitation includes such 

practices as removing weeds 

that harbor pest insects or 

rodents, eliminating weed 

plants before they produce 

seed, destroying diseased 

plant material or crop 

residues, and keeping field 

borders or surrounding 

areas free of pests and pest breeding 

sites. Animal manure management is 

an effective sanitation practice used 

for preventing or reducing fly 

problems in poultry and 

livestock operations. In 

non-agricultural areas, 

certain pests are controlled by draining 

standing water. Closed 

garbage containers 

and frequent garbage 

pickup eliminate food 

sources for flies, cockroaches, and rodents; 

removing soil, trash, and 

other debris from around and 

under buildings reduces termite 

and fungal rot damage and prevents 

rodent nesting.

Physical/Environmental 

Modification

Pests that occur in enclosed areas 

may sometimes be suppressed by 

altering physical and environmental 

conditions such as water, air movement, 

temperature, light, and humidity. 

Refrigeration, for example, protects 

stored food products, furs, and other 

items from insect pests; lowered temperatures either kill the insects, cause 

them to stop feeding, or prevent egg 

hatch or development. Installing bright 

lights in attics sometimes discourages 

bats from roosting there. Lowering the 

humidity of stored grains and other 

food products reduces damage from 

molds and some insects. Increasing air 

movement in glass or plastic houses

Live trap used to control vertebrate pests.

Use of plastic mulch to 

control weeds.

7

M.J. Weaver, Virginia Tech Pesticide Programs

USDA
CHAPTER 1

often helps to suppress fungal diseases 

from developing on plants.

Host Resistance or Genetic 

Control

Sometimes plants and animals can 

be bred or selected to resist specific pest 

problems. For example, particular livestock breeds are selected for physical 

characteristics that prevent attack by 

some pests or provide physiological 

resistance to disease or parasitic 

organisms. Resistance also is enhanced 

by maintaining the host’s health and 

providing for its nutritional needs. 

Certain plant varieties are naturally 

resistant to insects, pathogens, or 

nematodes. Many plants actually repel 

various types of pests, and some contain 

toxic substances. Plant resistance to 

insect pests can sometimes be achieved 

by transferring genetic material from 

certain insect-destroying microorganisms to hybrid seed. Genetic control 

has been widely used in the past and 

offers great promise for the future, 

especially when combined with new 

gene manipulation techniques.

Chemical Controls

Chemical controls are pesticides 

that are either naturally derived or 

synthesized. Pesticides often play a 

key role in pest management programs 

and frequently may be the only control 

method available. Major benefits associated with the use of pesticides are their 

effectiveness, the speed and ease of controlling pests, and, in many instances, 

their reasonable cost compared with 

other control options. Usually pest 

damage stops or pests are destroyed 

within a few hours (for insects) to a 

few days (for weeds) after application 

of a pesticide. Using a fungicide may 

provide immediate, short-term protection against microorganisms.

A pesticide is defined as any 

material that is applied to plants, the 

soil, water, harvested crops, structures, 

clothing and furnishings, or animals 

to kill, attract, repel, or regulate or 

interrupt the growth and mating of 

pests, or to regulate plant growth. 

Pesticides include a wide assortment 

of chemicals with specialized names 

and functions. They are commonly 

grouped according to the type of pest 

they control.

• Avicides control pest birds.

• Bactericides control bacteria.

• Disinfectants (antimicrobials) 

control microorganisms.

• Fungicides control fungi.

• Herbicides control weeds and 

other undesirable plants.

• Insecticides control insects and 

related arthropods.

• Miticides (acaricides) control 

mites.

• Molluscicides control snails and 

slugs.

• Nematicides control nematodes 

(roundworms).

• Predacides control predatory 

vertabrates.

• Piscicides control pest fish.

• Repellents repel insects, related 

invertebrates, birds, and mammals.

• Rodenticides control rodents.

• Defoliants cause leaves or foliage 

to drop from plants.

• Desiccants promote drying 

or loss of moisture from plant 

tissues.

• Growth regulators are substances (other than fertilizers 

or food) that alter the growth 

or development of a plant or 

animal.

Each group of pesticide includes 

several classes or families. For example, 

the classes of insecticides include, among 

others, the organophosphates, organochlorines, carbamates, pyrethroids, 

botanicals, insecticidal soaps, and microbials. The pesticides within a particular 

class have similar chemical structures 

or properties or share a common mode 

of action. The mode of action of a 

pesticide is how the pesticide works. In 

other words, it is what specific system(s) 

in the pest are affected by the pesticide. The various classes of chemicals 

8
Pest Management

work in different ways and present different risks and problems.

Pesticides also vary in their 

selectivity. Fumigants, for example, 

are non-selective, controlling a wide 

variety of pests—fungi, insects, weeds, 

nematodes, etc. Some non-selective 

herbicides control any plant given a 

sufficient dose. In contrast, selective 

products control only certain species 

of pests or affect only a certain stage of 

pest development. For example, certain 

herbicides control broadleaf weeds while 

not harming grasses, and ovicides kill 

only the eggs of certain insects, mites, 

and related pests.

Pesticides may move in various 

ways after they come in contact with a 

host. Systemic pesticides are absorbed 

through leaves or roots and then transported within the treated plant. Similarly, 

systemic insecticides can be eaten by or 

injected into livestock to control certain 

pests. By contrast, contact pesticides

are not absorbed by treated plants or 

animals. These pesticides must directly 

touch the pest or a site the pest frequents 

to be effective (see Figure 1.2).

Pesticides also vary in their 

persistence, or how long they remain 

active to control pests. Some residual 

pesticides control pests for weeks, 

months, or even years. Others provide 

only short-term control, sometimes 

lasting only a few hours.

The production, sale, use, storage, 

and disposal of all pesticides are regulated at both the federal and state levels. 

The federal laws and regulations governing all aspects of pesticide use and 

handling are covered in Chapter 2.

Regulatory Pest Control

Some pest problems cannot be 

controlled successfully at a local level. 

These problems involve pests that seriously endanger public health or are 

likely to cause widespread damage to 

agricultural crops or animals, forests, 

or ornamental plants. Quarantine or 

eradication programs directed by governmental agencies according to federal 

and state laws are used to prevent the 

introduction and spread of such pests.

Quarantine is a pest control 

process designed to prevent entry of 

pests into pest-free 

areas. Some states 

maintain inspection stations at all major entry 

points to intercept pests 

or materials that might 

harbor pests. Regulatory 

agencies monitor airports and ocean ports. 

Quarantine also prevents movement of 

designated pests within 

a state. Produce and 

other identified items 

being shipped from a 

quarantine area must 

be fumigated to destroy 

pests before shipment. 

Nursery stock, plant 

cuttings, and budding 

and grafting material are 

also regulated to prevent 

the spread of pests. 

Eradication is the total elimination of a pest from a designated 

area; often, these pests are under quarantine restrictions. When eradication 

is required, the geographical extent 

of pest infestation is determined and 

control measures are taken to eliminate this pest from the defined area. 

Procedures may include an areawide 

spray program, releasing sterile 

insects, using mechanical and cultural 

practices, and intensive monitoring for 

pests within and around the borders of 

the infested area. 

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Figure 1.2

Systemic and contact 

pesticides on treated 

plants.

USDA regulates and 

inspects imported 

cargo to prevent pest 

introduction.

9

USDA APHIS

Adapted from Penn. State 

Pesticide Education Manual
CHAPTER 1

Government agencies are authorized to destroy weeds and plants that 

cause fire hazards, harbor harmful 

pathogens or animals, or are noxious 

to people or livestock in and around 

agricultural areas. Similar authority 

applies to diseased or infected livestock 

or poultry and to weeds and nuisance 

plants in residential, commercial, and 

industrial areas. Mosquito abatement 

is an important pest control function 

undertaken to protect public health. 

Under the authority of mosquito 

abatement laws, state agencies drain 

or treat standing water that provides 

breeding sites for mosquitoes.

INTEGRATED PEST management (IPM)

Pesticide use is and will continue to be 

significant in food and fiber production, 

forestry, turf and landscape maintenance, and public health. In recent 

years, pest management has shifted 

from relying heavily on pesticides to 

using an integrated approach based on 

pest assessment, decision making, and 

evaluation. Using integrated pest management has benefited pest managers 

and the environment, and has reduced 

the occurrence of pesticide resistance in 

pest populations. 

Integrated pest management (IPM) 

is a balanced, tactical approach to pest 

control. It involves taking action to 

anticipate pest outbreaks and to prevent 

potential damage. IPM is a pest management strategy that utilizes a wide 

range of pest control methods or tactics. 

The goal of this strategy is to prevent 

pests from reaching economically or 

aesthetically damaging levels with the 

least risk to the environment. Such pest 

management programs—based on the 

identification of pests, accurate measurement of pest populations, assessment 

of damage levels, and knowledge of 

available pest management strategies or 

tactics—enable the specialist to make 

intelligent decisions about control. IPM 

offers the possibility of improving the 

effectiveness of pest control programs 

while reducing some of the negative 

effects. Many successful IPM programs 

have reduced energy and pesticide use. 

IPM programs are very site-specific. 

Why Practice IPM?

You might be wondering why pest 

managers have shifted to IPM when 

chemical pesticides so often succeed 

at controlling pests. There are many 

reasons to broaden pest management 

beyond the use of chemicals.

IPM helps to keep a balanced 

ecosystem— Every ecosystem, made 

up of living things and their non-living 

environment, has a balance; the actions 

of one kind of organism in the ecosystem 

usually affect other species. Introducing 

chemicals into the ecosystem can change 

this balance, destroying certain species 

and allowing other species (sometimes 

pests themselves) to dominate. Pesticides 

can kill beneficial insects that consume 

pests, leaving few natural mechanisms 

of pest control.

Pesticides can be ineffective—

Chemical pesticides are not always 

effective. As mentioned earlier, pests 

can become resistant to pesticides. In 

fact, some 600 cases of pests developing 

pesticide resistance have been 

documented to date, including many 

common weeds, insects, and diseasecausing fungi. Furthermore, pests may 

survive in situations where the chemical 

does not reach pests, is washed off, is 

Integrated Pest 

Management (IPM)

A pest management strategy

that utilizes a wide range of

pest control methods or tactics.

The goal of this strategy is to

prevent pests from reaching

economically or aesthetically

damaging levels with the least

risk to the environment.

10
Pest Management

applied at an improper rate, or is applied 

at an improper life stage of the pest.

IPM can save money— IPM can 

avoid crop loss and landscape and 

structural damage caused by pests and 

prevent unnecessary pesticide expense. 

Applicators can save on pesticide costs 

because the need for control rather than 

the calendar is the basis for applying 

pesticides.

IPM promotes a healthy environment­—We have much to learn 

about the persistence of chemicals in 

the environment and their effect on 

living creatures. Cases of contaminated 

groundwater appear each year, and disposal 

of containers and unused pesticides still 

pose challenges for applicators. Make 

sure that environmental impacts are 

considered in any pest management 

decisions. Using IPM strategies helps 

keep unreasonable adverse effects to a 

minimum.

IPM maintains a good public 

image—IPM is now demanded by 

many sectors of our society. IPM has 

been implemented to grow our food, to 

manage turf and ornamentals, to protect 

home and business structures, to manage 

school grounds, and to protect humans, 

pets, and livestock health. 

Components of IPM

All of the components of an IPM 

approach can be grouped into five 

major steps: identify the pest and 

understand its biology, monitor the 

pest to be managed, develop a sound 

pest management goal, implement an 

IPM program, and record and evaluate 

results.

1. I dentif y the Pest and 

Understand its Biology— Despite 

our best preventive efforts, some pest 

outbreaks inevitably occur. The first 

step in any pest management program 

is to identify the pest. Never classify an 

organism as a pest or treat it as a pest 

until it is clearly determined to be one. 

Identification is important whether you 

are dealing with an insect, weed, plant 

disease, or vertebrate.

The more that you know about a 

pest, the easier and more successful pest 

management becomes. Once you have 

identified a pest, you can access information about its life cycle and behavior, 

the factors that favor development, and 

the recommended control procedures. 

You can also determine the significance 

of the pest and the need for control. 

Some pests have little impact on a plant, 

animal, or structure and do not require 

control. Other pests warrant immediate 

control because they cause serious 

damage or present a significant threat 

to human health or public safety.

Most pests may be classified either 

as key pests, occasional pests, or secondary pests.

Key pests may cause major damage 

on a regular basis unless they are controlled. Many weeds, for example, are 

key pests because they compete with 

crop or ornamental plants for resources 

and require regular control efforts to 

prevent or reduce damage.

Occasional pests become troublesome only once in a while because of 

their life cycles or environmental influences, or as a result of human activities. 

For instance, ants sometimes become 

occasional pests when sanitation practices change, providing them with food 

where previously none existed. They 

also may move into buildings after 

a rainfall or other event destroys an 

outdoor food source.

Secondary pests become problems 

when a key pest is controlled or eliminated. For example, some weed species 

become pests only after key weeds, 

which are normally more successful in 

competing for resources, are controlled. 

Certain species of fleas, ticks, and bloodfeeding bugs attack people only when 

their natural hosts, such as pet dogs or 

cats, are no longer present.

2. Monitor the Pest to be Managed—The key to a successful 

IPM program is regular monitoring. 

Monitoring involves measuring pest 

populations and/or the resulting damage 

or losses. The procedures for monitoring 

vary with the pest and the situation.

Scouting and trapping are commonly used to monitor insects and their 

activity. Weather and temperature data 

Why Practice 

IPM?

• IPM helps to

keep a

balanced

ecosystem.

•  Pesticides can be

ineffective.

•  IPM can save

money.

•  IPM promotes a

healthy

environment.

•  IPM maintains

a good public

image.

11
CHAPTER 1

are particularly helpful 

in following a pest’s life 

cycle or in predicting 

how long it takes a certain 

pest to develop. Models 

have been developed for 

a number of insects and 

plant diseases to predict 

the need for and timing 

of pesticide applications.

Use Pest Population 

Thresholds

Producers of agricultural or ornamental 

products must understand 

the concept of economic 

thresholds. The presence 

of a pest does not always 

cause a loss in quality or 

quantity of an agricultural 

or ornamental product. To 

justify the cost of control, 

pest populations must 

be large enough to cause 

significant damage. This 

population level is called the economic 

threshold (ET). The economic threshold 

is the pest population density (number of 

pests per unit of area) at which control 

measures are needed to prevent the pest 

from reaching the economic injury level. 

The economic injury level (EIL) is the 

pest population density that causes losses 

equal to the cost of control measures. To 

make a control practice profitable, or at 

least break even, it 

is necessary to set 

the ET below the 

EIL (see Figure 

1.3). Otherwise, 

producers lose 

money, first from 

the damage caused 

by the pest, and 

then by the cost 

of applying the 

control. Setting the 

ET below the EIL 

triggers pesticide application and other 

controls before pests reach the economic 

injury level.

Economic thresholds are available 

for many pests and crops. Several factors 

can influence an economic threshold. 

These factors include the current 

value of the agricultural or ornamental 

product, its stage of development, the 

degree of damage caused under various 

environmental conditions, the cost and 

effectiveness of control measures, and the 

anticipated yield. For example, even slight 

damage to an ornamental or floricultural 

crop may reduce the value significantly 

and render it unsalable, so the economic 

threshold must be set quite low.

For pest managers who are not 

directly involved in production, the 

concept of action thresholds is more 

appropriate. An action threshold is the 

pest level at which some type of pest 

management action must be taken. It is a 

predetermined pest level that is deemed 

to be unacceptable. Factors besides 

economics come into consideration for 

establishing action thresholds. In some 

situations, the action threshold for a 

pest may be zero (i.e., no presence of the 

pest is tolerated). This is especially true 

when the pest is capable of transmitting 

a human pathogen (mosquitoes and the 

West Nile virus), has a venomous bite or 

sting (some spiders, wasps), or may create 

a public health emergency (cockroaches, 

rodents). In an urban landscape, action 

thresholds must consider not only the 

economic value of the landscape but also 

its ecological and aesthetic roles. Even 

a slight amount of pest damage may be 

unacceptable in such an environment. 

Action thresholds can vary by pest (a 

stinging insect in a classroom vs. an 

ant), by site (a storage room vs. a school 

infirmary), and by season (some pests 

are present only a few weeks out of an 

entire year). Often the action threshold is 

expressed as the number of pests per unit 

area. Below the action threshold level, 

IPM technicians do not use any control 

measures, though they should continue 

to monitor the situation and do sanitation inspections as needed. Once a pest 

is at or above the action threshold, the 

technician should implement a full range 

of IPM strategies to control the pest.

Action thresholds are easy to 

understand, but establishing them is 

more difficult. In a new IPM program, 

a practical approach is to establish an 

arbitrary action threshold for the major 

pests you encounter. As you gain insight 

and experience into specific pest management settings, the action levels can 

be revised up or down.

Pest monitoring by using 

a sweep net. ÕLiÀÊvÊ*iÃÌÃ

/i

1ÌÀi>Ìi`


VVÊ

ÕÀÞÊiÛi

*iÃÌÊ««Õ>Ì

/Ài>Ìi`


VV

ÌÀiÃ`

/iÊÌÊ

ÌÀi>Ì

Figure 1.3

To make a control 

practice profitable, or 

at least break even, it 

is necessary to set the 

economic threshold (ET) 

below the economic 

injury level (EIL).

12

Peggy Greb, USDA ARS
Pest Management

3. Develop the Pest Management 

Goal—The goal of most IPM programs is to maintain pest damage 

at economically acceptable levels. 

Prevention and suppression techniques 

are often combined in an effective IPM 

program. In rare instances, eradication 

may be the goal of an IPM program. 

Once the goal of the program has been 

determined, the strategy for a sound 

IPM program is to coordinate the use of 

multiple tactics into a single integrated 

system. Pesticides are just one method 

for controlling pests. Non-chemical 

methods may provide longer and more 

permanent control of a pest and should 

always be considered when developing 

a pest management strategy. Evaluate 

the costs, benefits, and liabilities of 

each control tactic.

Prevention

Often economical and environmentally sound ways are available to 

prevent loss or damage from pests. Such 

techniques include planting weed- and 

disease-free seed and growing varieties 

of plants resistant to diseases or insects. 

Other choices are using cultural controls to prevent weedy plants from 

seeding and choosing planting and 

harvesting times that minimize pest 

problems. Sanitation methods often 

reduce the buildup of pests. Other 

preventive methods involve excluding 

pests from the target area or host and 

using practices that conserve natural 

enemies. Making sure that plants, 

poultry, or livestock receive adequate 

water and nutrients often reduces stress 

and susceptibility to diseases or pests.

Pesticides are sometimes used for 

pest prevention. For instance, growers 

treat some crops and landscapes with 

preplant or preemergence herbicides 

because they know weed seeds are 

present. If plant pathogens have already 

infected susceptible plants, economic 

damage usually cannot be prevented. 

For this reason, fungicides are normally applied before infection occurs 

whenever environmental conditions 

favor infection. Likewise, pesticides 

are applied to structural lumber before 

construction to protect it from insects 

and fungi.

Suppression

Suppressive pest control methods 

are used to reduce pest population 

levels. The methods chosen usually do 

not eliminate all pests but reduce their 

populations to a tolerable level or to a 

point below an economic injury level; 

additional suppressive measures may 

be required. Suppression sometimes 

lowers pest populations so natural 

enemies are able to maintain control. 

Suppression is the goal of most pesticide applications. Other techniques, 

such as cultivation or mowing of 

weeds and release of biological control 

agents, are also used to suppress pest 

populations.

Eradication

Eradication is the total elimination 

of a pest from a designated area. This 

is a common objective of pest control 

efforts in buildings or other small, 

confined spaces where, once the pest 

is eliminated, it can be excluded. For 

example, eliminating cockroaches, 

rats, and mice from commercial food 

establishments involves eradication. 

Over larger areas, however, eradication is very expensive and often has 

limited success. Large eradication 

programs are usually directed at exotic 

or introduced pests posing an areawide 

public health or economic threat. Such 

programs are generally coordinated 

by governmental agencies. Efforts to 

eliminate Mediterranean fruit fly and 

hydrilla (an aquatic weed) in California 

and Florida, respectively, are examples 

of this type of pest management. 

The pest control strategy you 

choose depends on the nature of the 

pest, the environment of the pest, and 

economic or tolerance considerations. 

Combining prevention and suppression techniques usually enhances a 

pest management program. Objectives 

sometimes differ, however, for the 

same pest in different situations. For 

example, the Mediterranean fruit 

fly (Med fly) is an established pest in 

Hawaii, so the emphasis there is to use 

prevention and suppression techniques 

to reduce crop damage. Regulatory 

agencies in California and Florida, 

however, use eradication measures to 

13
CHAPTER 1

Pesticides often play a significant 

role in pest management programs. 

Their use requires certain precautions 

be taken to avoid the development of 

resistant pest populations. Although 

pest resistance can occur, it does not 

cause every pesticide failure. Make sure 

that you have used the correct pesticide 

and the correct dosage, and that you 

have applied the pesticide according 

to label instructions. Sometimes a 

pesticide application fails to control a 

pest because the pest was not identified 

correctly and the wrong pesticide was 

chosen. Other applications fail because 

the pesticide was not applied at the 

correct time—the pest may not have 

been in the area during the application, 

or it may have been in a life cycle stage 

or location where it was not susceptible 

to the pesticide. Also, remember that 

the pests that are present may be part 

of a new infestation that developed long 

after the chemical was applied.

Even non-chemical pest management tactics become ineffective if 

the pest and the susceptible stage(s) of 

its life cycle are not identified correctly. 

Successful pest management programs 

do not happen by accident—they 

depend on careful observation, a 

thorough knowledge of the pest and the 

damage it causes, an understanding of 

all available pest control options, and a 

caring, professional attitude. 

Pesticide Resistance

Pesticide resistance can be defined 

as the ability of an insect, fungus, weed, 

rodent, or other pest to tolerate a pesticide that once controlled it. Resistance 

develops because intensive pesticide 

use kills the susceptible individuals in 

a population, leaving only the resistant 

ones to reproduce. Initially, higher 

labeled rates and more frequent applications are needed to control resistant 

pests. Eventually, however, the pesticide 

prevent the Mediterranean fruit fly 

from becoming permanently established in these states.

4. Implement the Integrated Pest 

Management Program— The following steps should be taken before 

implementing an IPM program:

• Identify the pest.

• Set up a monitoring program.

• Know the pest level that triggers 

control.

• Know what control methods are 

available.

• Evaluate the benefits and risks of 

each method.

When implementing the IPM 

program, try to select the methods 

that are the most effective and the least 

harmful to people and the environment. 

Use several methods whenever possible, and be sure to use them correctly. 

It is also important to observe all local, 

state, and federal regulations regarding 

the methods chosen. 

5. Record and Evaluate Results— 

It is extremely important to record and 

evaluate the results of your control 

efforts. Some control methods, especially non-chemical procedures, are 

slow to yield measurable results. Other 

methods may be ineffective or even 

damaging to the target crop, animal, 

treated surface, or natural predators 

and parasites. Consider how well your 

strategies work and their impact on 

the environment before implementing 

them again.

Components 

of IPM

1. Identify the pest

and understand

its biology.

2. Monitor the pest

to be managed.

3. Develop the pest

management

goal.

4. Implement the

integrated pest

management

program.

5. Record and

evaluate

results.

EFFECTIVENESS OF PEST management PROGRAMS

14
Pest Management

will have little or no effect on the pest 

population (see Figure 1.4).

Resistance may develop to only a 

single insecticide, fungicide, herbicide, 

or rodenticide. More often, however, 

pest populations become resistant to all 

chemically related pesticides in a class 

of compounds. It is also possible for a 

pest to develop resistance to pesticides 

in two or more classes of compounds 

with unlike modes of action.

Continual use of pesticides from the 

same chemical class, such as all organophosphate or all pyrethroid insecticides, 

increases the likelihood that resistance will develop in pest populations. 

Frequent applications and persistence 

of the chemical further increase the 

chances of resistance occurring. Finally, 

the spread of resistance through a 

pest population can occur much more 

rapidly in pests that have many generations per year and many offspring per 

generation, such as many insects, fungi, 

and rodents.

Several pest management tactics 

help prevent or delay the occurrence 

of pesticide resistance. One approach 

involves the use of new or altered pesticides. Using new compounds with 

different modes of action will lessen 

the likelihood of resistance developing 

in a population. Unfortunately, new 

replacement products are often quite 

complex, difficult to synthesize, and 

very costly to develop, and they have 

very specific modes of action, which 

can rapidly lead to the development 

of resistant pest populations even after 

very limited use in the field. No longer 

can we expect to respond to pesticide 

resistance by merely substituting one 

pesticide for another.

Changing pesticide use patterns is 

an important step in preventing resistance. When dosages are reduced, fewer 

pests are killed, so the 

pressure to develop 

resistant pest populations is decreased. 

Applying pesticides over 

limited areas reduces 

the proportion of the 

total pest population 

exposed to the chemical, 

thereby maintaining a 

large pool of individuals 

still susceptible to the 

pesticide. This tactic has a tendency 

to delay the development of a resistant 

population because pesticide-susceptible 

individuals in the population continue 

to interbreed with resistant ones, thus 

diluting the resistance in the population. 

Also, treating alternate generations of 

pests with pesticides that have different 

modes of action decreases the selection 

pressure for resistance.

Managing pesticide resistance is a 

very important aspect of integrated pest 

management. Monitor pest populations 

carefully and treat only when necessary, 

rather than treating on a calendar basis. 

Good pesticide application records are 

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Resistance Management

•  Use new or altered pesticides.

•  Change pesticide use patterns.

•  Treat only when necessary.

15

Adapted from U. of C. The Safe and Effective Use of Pesticides
CHAPTER 1

an important component of resistance 

management. Pesticides are more effectively managed when treatment history 

is known. Resistance must be detected 

when it is at a very low level and then 

controlled by using all available pest 

management techniques to extend the 

useful life of our current pesticides.

To be successful, a pest management 

program must start with the proper 

identification of the pest. Choosing the 

appropriate pest control method depends 

on recognizing and understanding the 

pest, its life cycle, habits, and habitat. 

Integrated pest management (IPM) programs attempt to balance the need for 

pest control with the desire to protect 

the environment from risks associated 

with pesticide use. IPM methods include 

both chemical and non-chemical means 

to prevent and control pest populations 

from reaching economically damaging 

levels. These prevention and control 

tactics include biological, mechanical, 

cultural, physical, genetic, chemical, and 

regulatory methods.

 Monitoring techniques used in IPM 

programs are critical to knowing when 

and what type of control measures to 

apply. Monitoring also helps to establish 

pest population thresholds that may 

be used for deciding when pest control 

action should be taken. Evaluation and 

recording results help to determine how 

well the IPM program is working and 

whether there are any harmful human 

or environmental effects. 

Minimizing pesticide resistance 

is also an important consideration for 

sustaining the effectiveness of pest 

management programs. Many tools and 

techniques are available (e.g., rotation of 

pesticide types with different modes of 

action, application of pesticides that do 

not leave persistent residues, application 

of pesticides at below-label amounts) 

that prevent or delay the occurrence of 

pesticide resistance. Whenever chemical 

controls are used, it is critical to read 

and follow all label directions correctly 

to avoid misapplication. 

If the pest has not been properly 

identified, even non-chemical means 

of pest control will fail. It is the applicator’s responsibility to consider all of 

the factors relevant to the pest control 

situation. Beyond simply identifying the 

pest and choosing a control strategy, 

the applicator must consider the effects 

of pest control actions on the entire 

treatment site, whether an outdoor 

area or inside a structure. Use good 

judgment, especially when pesticides 

are part of the control strategy, to avoid 

harmful effects to other living organisms 

and the environment.

SUMMARY

16