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larval instars – the colonizers. Such a division is of

great survival value to a species.

0003 Insects are the most successful animal class. Their

great variation in food and other environment

requirements is of great survival value. Additionally

they have enormous dispersal abilities by wing, wind,

and piggybacking on higher animals such as birds,

bats, and flightless animals, including humans, and

this has led to wide distribution for many species.

Today, with the assistance of worldwide commerces,

insects have now colonized every continent except

Antarctica. Many species which now find human

food, feed, seed, and fiber as their food and environ-

ment are cosmopolitan.

Classification

0004 In order to explain the success of these groups of pests

of humans, it is essential to learn something of their

classification and their developmental biology. An

appreciation is needed of these insect and mite pests

in their proper place among all the other animals of

the world. In an effort to arrange the world’s animals

in an orderly manner, humans have developed a

hierarchical classification system of seven primary

groupings. Each of these groups may have supra- or

sublevels, and in some instances additional primary

groups are added to accommodate animal groupings

that have a large number of species. For our purposes,

simply recognizing the seven classification groups

presented in Table 1 will suffice for this discussion.

0005 The individuals in the animal kingdom are distin-

guished from those in the plant kingdom by their

ability to move from place to place and their ability

to make food from inorganic materials. While there

are some exceptions to these characteristics for the

animal kingdom, they will not affect our discussion of

the phylum Arthropoda. It is in this phylum that we

find our insect and mite pests along with their close

relatives. Arthropoda is the animal kingdom’s largest

phylum, in terms of both number of species and the

number of individuals. Six distinct classes of animals

are readily recognized in the phylum Arthropoda.

Several other classes have been placed in this class

from time to time by various specialists, but again the

placement of these questionable classes will not affect

our discussion.

0006The major characteristics of the phylum Arthro-

poda are as follows: (1) the body is segmented; (2)

the appendages are paired and segmented; (3) the

body possesses an exoskeleton; and (4) the body is

bilaterally symmetrical.

0007By using these four characteristics for the phylum

we can develop a simple key that will distinguish for

us the main classes of Arthropoda and show us some-

thing of their relationships.

1a.

0008Aquatic species (2 go to couplet)

1b.

0009Aerial species, but some may be limited to very

moist environments (3 go to couplet)

2a.

0010Marine species without antennae. This class is

represented by a single species: Xiphosura poly-

phemus, the horseshoe crab: class Merostomata

2b.

0011Both marine and fresh-water species, possessing

two pairs of antennae and at least five pairs of

legs, e.g. crayfish, lobsters and shrimps: class

Crustacea (in part)

3a.

0012Possess two pair of antennae and live in moist

environments, e.g., sowbugs, pillbugs (order

Isopoda) and shrimp fleas (order Amphipoda):

class Crustacea (in part)

3b.

0013Does not possess two pairs of antennae (4 go to

couplet)

4a.

0014Possess no antennae, four pair of legs as adults,

and have only two apparent body regions (ceph-

alothorax and abdomen), e.g., spiders, scorpions,

ticks, and mites (order Acarina): class Arachnida

4b.

0015Possess one pair of antennae (5 go to couplet)

5a.

0016Possess more than three pairs of legs and no

wings (6 go to couplet)

5b.

0017Possess three pairs of legs and usually wings in

the adult stage, e.g., beetles, moths, cockroaches,

and flies: class Insecta

6a.

0018Possess two pairs of legs on the same body seg-

ment, e.g., millipedes: class Diplopoda

6b.

0019Possess one pair of legs on each body segment,

e.g., centipedes: class Chilopoda

In the protection of agricultural commodities (food,

feed, seed, and fiber) we are primarily interested in

the mites, class Arachnida, order Acarina, and the

insects, class Insecta, primarily the orders Lepidop-

tera (moths) and Coleoptera (beetles).

0020The classes Insecta and Arachnida are very large

animal groupings from the standpoint of both

numbers and species. While the total number of

animals species worldwide is often debated, it can

really be stated that the arthropods, principally the

insects and mites, represent over 90% of the known

tbl0001 Table 1 Classification of the animal kingdom

Classification Examples

Insects Mankind

Kingdom Animalia Animalia

Phylum Arthropoda Chordata

Class Insecta (Hexapoda) Mammalia

Order Coleoptera Primata

Family Tenebrionidae Hominidae

Genus Tribolium Homo

Species confusum sapiens

3320 INSECT PESTS/Insects and Related Pests

and described species. There are various estimates of

this number, but it is safe to say that the known and

described species would easily exceed one million.

Fortunately, the number of species infesting our

stored subsistence and fiber is quite limited. A US

Department of Agriculture publication provides an

illustrated key listing 650 species of insects and

mites known to infest food in the USA. As most

insects attacking stored subsistence have traveled

with their food around the world, they are considered

as cosmopolitan in distribution. A publication of

the American Peanut Research and Education

Society lists 120 species collected in the south-eastern

USA on stored-in-shell peanuts, an excellent host

for many insects attacking stored food. However,

they only elected to discuss 21 of these species

as major pests. Many of the others collected were

parasites and predators on the pests, or insects

that attack peanuts which are out of condition, e.g.,

possessed a high moisture content, were moldy, or

had an excessive amount of debris mixed with the

peanuts.

0021 Mite species attacking stored commodities would

likewise be quite limited. Only 16 mite genera have

been listed as possessing species attacking stored

commodities. Here again most other species found

in stored commodities are predators of insects and

mites infesting the commodity. These naturally occur-

ring parasites and predators, e.g., members of the

mite genus Pyemotes (family Pyemotidae), which

prey on insects infesting the commodity, are often

as serious a problem as the phytophagous species.

Members of this family will often attack humans

and cause a dermatitis known as ‘grocer’s itch.’

These mites and insects are food contaminates and

will be considered as filth by sanitarians and food

inspectors. However, it must be realized that the man-

agement of phytophagous insects and mites will in

turn control these insects and mite contaminates. (See

Parasites: Occurrence and Detection.)

0022 When infestations of birds, rodents, or bats exist

within or close to storage facilities, there may occur in

and on the commodities, and its packaging, insects

and mite parasites, as well as predators of these

higher animals. Some of these parasites and predators

may also attack humans, and their occurrence will

always be considered to be evidence of unsanitary

storage conditions.

0023 It is probably safe to say that for most stored sub-

sistence we will find a limited number of major pests

among those found infesting the commodity. There

will be a slight variation in the species complex for

each commodity and for that part of the world where

the storage takes place. However, this latter variation

will usually be quite small and perhaps go unnoticed

because most of these pests are cosmopolitan,

resulting from world trade in commodities.

0024For the convenience of humans, the insects and

mites attacking stored commodities have been

grouped in nonscientific ways by those responsible

for handling the commodities and those responsible

for controlling these pests. These groupings are

artificial and primarily designed to assist warehouse-

workers, pest control operators, sanitarians, and

farmers in discussions of their observations. In the

protection of stored whole grain, one often speaks

of internal feeders, external feeders, scavengers, and

secondary and tertiary feeders. If the commodity is a

packaged product the terms become penetrators and

invaders. The terms long-lived and short-lived will,

on occasion, be used in relation to adults. Other terms

heard will be grain beetles, flour beetles, grain moths,

flour moths, mealworms, warehouse beetles, fabric

pests, hide beetles, and many others, depending upon

their environment and/or their food habits. Most of

these terms are self-explanatory. Several are not and

will be defined below and followed by examples.

Pests of Stored Plant Products (Seeds)

Internal Feeders

0025These insect larvae feed entirely within the seed.

Examples of internal feeders include the rice, granary,

and maize weevils, Sitophilus spp., the Angoumois

grain moth, Sitotroga cerealella (Olivier), and all the

bean and pea weevils.

External Feeders

0026All stages of these insects feed outside the seed.

Examples of external feeders include the lesser grain

borer, Rhyzopertha dominica (F.) the khapra beetle

Trogoderma granarium Evert, and the cigarette

beetle, Lasioderma serricorne (F.)

Scavengers

0027These insects feed on seeds only after the seed coat is

broken. Examples of scavengers include the flour

beetles, Tribolium spp., flat grain beetles, Crypto-

lestes spp., and grain beetles, Oryzaephilus spp.

Secondary Feeders

0028These insects feed only on products that are deterior-

ated, damp, and moldy. Examples of secondary feeders

include Tenebrio and Alphitobius spp., mites Acarus siro

L. and Tyrophagus spp., and psocids, Liposcellis spp.

Penetrators

0029These insects have the ability to penetrate many of the

types and combinations of paper, films, and foils used

INSECT PESTS/Insects and Related Pests 3321

in packaging. Examples of penetrators include the

lesser grain borer, cigarette beetle, and many of the

moth larvae.

Invaders

0030 These insects usually depend upon openings in the

packages resulting from the manufacturing process,

or openings made by penetrating insects. Examples of

invaders include the flour beetles and the grain beetles.

Pests of Animal Products

0031 Some insects and mites need or prefer a diet higher in

protein than they can secure by feeding exclusively on

plant-derived foods. These pests feed on dried meats,

hair, feathers, dried fish, and on processed animal

products such as woolen cloth, dried milk and eggs,

fishmeal, cheese, and leather. These pests can be

grouped according to the foods eaten. The following

are some of the more common and important group-

ings.

Fabric Pests

0032 Fabric pests feed on keratinous materials such as

wool cloth, mohair, and hair, and include such species

as the clothes moths, Tinea and Tineola spp., and the

carpet beetles, Attagenus and Anthrenus spp.

Pests of Hides and Skins

0033 These pests will feed on green hides and skins, and

can cause considerable damage and defects. Pests of

hides and skins include several species of the genera

Dermestus and Trogoderma spp., the ham beetle,

Necrobia rufipes (DeGeer), the spider beetles, Ptinus

spp., flesh flies Sarcophaga spp., carpet beetles of the

genera Attagenus and Anthrenus spp., and the cheese

skipper, Piophila casei (L.).

Pests of Processed Animal Products

0034 These insects can be represented by almost any of the

above species as well as many of the species that

commonly feed on processed plant products. Many

animal feeds are mixtures of both animal- and plant-

derived products.

Pests of Root Crops

0035 In the part of the world where root crops are com-

monly stored dry, they are attacked by many of the

boring beetles that are known to attack dried grain

and harvested wood, e.g., the lesser grain borer.

Pests of Perishables

0036 The most common pests of perishables such as

fresh fruits, particularly those fruits of tropical and

subtropical origins, are the fruit flies of the insect

family Trypetidae, e.g., the Mediterranean fruit fly.

Pests of Dried Fruits and Nuts

0037These commodities have many insect pests, many of

which come in from the field at harvest time. They

include pests that feed on the commodity and also on

the fungus and molds that grow on and in the com-

modity. Major pests include several moth species,

e.g., the almond moth, Cadra cautella (Walker),

beetle species of the genera Tribolium spp., Oryzae-

philus spp., and Carpophilus spp.

Mite Pests

0038The phytophagous mites attacking and infesting

stored commodities must be classified as scavengers.

In some instances they have been recorded as

attacking sound kernels of grain and consuming the

germ. This is questionable, but most probably the

grain possessed a high moisture content, and fungi

has infested the germ and the kernel. Like insects,

mites contaminate much more commodity than they

consume – with their feces, odors, cast skins, and

dead bodies. As with the insects, scavengers and

secondary feeders, contamination by mites suggests

that the commodity is out of condition.

0039Unfavorable temperatures and relative humidities

will result in significant deterioration of the commod-

ity for further spread of insect, mite, and fungi infest-

ations.

Developmental Biology

0040It is important that we understand the biology and life

cycles of these pests of our food and fiber. All insect

and mite pests develop from eggs. Most young hatch

from the egg after the female lays it, but a few are

born alive from eggs that hatch inside the mother.

Following the hatching, these pests develop in a step-

wise fashion by stages. Each stage is limited in size by

the space provided inside the exoskeleton. As the pest

develops it lays down a new exoskeleton beneath the

current one. At specific times, determined by hormo-

nal action, the old exoskeleton splits down the back

of the pest and the next stage emerges and expands to

its new size limitation. The process of shedding an old

exoskeleton and emerging with a new exoskeleton is

called moulting. Usually an insect will have four to

eight moults but some insects, e.g., members of the

family Dermestidiae, can have more than 20 moults.

The period of time between moults is called an instar.

0041During growth, insects change not only in size but

also in form. In some instances the only change will

be maturity and development of the sexual organs

3322 INSECT PESTS/Insects and Related Pests

while in other species the changes will be quite start-

ling. This process of change accompanying growth is

called metamorphosis. There are four distinct types of

metamorphosis in insects: ametamorphosis, gradual

metamorphosis, incomplete metamorphosis, and

complete metamorphosis.

0042 In ametamorphosis there is very little change in form

as the insect grows, and the only visual changes will

be size and sexual maturity. An example of an insect

possessing this type of metamorphosis is the silverfish.

0043 In gradual metamorphosis the insect develops from

egg to nymph to adult. The nymphs resemble the adult

except that they are smaller, not winged or sexually

mature. An example of an insect with this type of

metamorphosis is the grasshopper.

0044 Incomplete metamorphosis involves much greater

body changes than those in gradual metamorphosis.

The young have a completely different body structure

and habitat from the adults. The young are aquatic

and called naiads. The adults are terrestrial and often

winged. An example of an insect with this type of

metamorphosis is the dragonfly.

0045 In insects with complete metamorphosis we find

four distinct life stages: egg, larva, pupa, and adult.

The larva is worm-like in appearance, but its activity

varies from a rapidly moving individual or free-living

larva to legless grubs found inside seeds. The pupal

stage, which is a resting stage between the larva and

adult, is really a very active time. It is at this time that

the larval body is broken down and the adult body

constructed. The last stage, the adult, which is often

very different from the larva and pupa, has as its main

function dispersal, mating, and extending or finding

new habitat.

0046 Members of the class Arachnida also possess a

form of metamorphosis, but changes are not so ex-

tensive as those in insects. In the Acarina (mite) there

are usually four life stages: egg, larva, nymph, and

adult. The larva has only six legs and there are three

nymphal stages. The nymphs appear to resemble the

adults, but are not sexually mature.

0047 Some species in both the insects and mites have or

can develop forms, during the larval and nymphal

stages respectively, that are resistant or tolerant to

adverse environmental conditions. These resistant

or tolerant stages are referred to as a condition of

diapause in insects and as a hypopus in a mite.

0048 Most of the insect pests of food, feed, seed, and

fiber have complete metamorphosis. This type of

development allows for the larva and adult to have

separate ecological niches on the same food or separ-

ate habitats for all their life activities. This develop-

mental method has great survival value. The various

life stages within the species development usually do

not cause any population pressure on each other.

0049The study of insects and mites and their relation-

ship to the welfare of humans has been both a valued

and an interesting pursuit of science. Elucidating their

behavior, physiology, and genetics has led and will

continue to lead to newer and safer ways to control

these animals with a penchant for our food and fiber.

See also: Insect Pests: Problems Caused by Insects and

Mites; Parasites: Occurrence and Detection

Further Reading

Anonymous (1986) Stored-Grain Insects. Agriculture

Handbook no. 500. Washington, DC: US Department

of Agriculture, Agricultural Research Service.

Baker EW and Wharton GW (1952) An Introduction to

Acarology. New York: MacMillan.

Comstock JH (1950) An Introduction to Entomology, 9th

edn. New York: Comstock.

Gorham JR (ed.) (1978) Training Manual for Analytical

Entomology in the Food Industry. FDA Technical Bul-

letin no. 2, Washington, DC: Food and Drug Adminis-

tration, US Department of Health, Education and

Welfare.

Gorham JR (ed.) (1987) Insect and Mite Pests in Food:

An Illustrated Key. Agricultural Handbook no. 655.

Washington, DC: US Department of Agriculture.

Hughes AM (1961) The Mites of Stored Foods. Ministry of

Agriculture, Fisheries and Food, Technical Bulletin no.

9. London: Her Majesty’s Stationary Office.

Monro JW (1966) Pests of Stored Products. The Rentokil

Library. London: Hutchinson.

Redlinger LM and Davis R (1982) Insect control in post-

harvest peanuts. In: Pate E and Young CT (eds) Peanut

Science and Technology, pp. 520–570. Texas: American

Peanut Research and Education Society.

Problems Caused by Insects

and Mites

R Davis, Pest Management Consultants and

Associates, Savannah, GA, USA

Background

0001In 1978, contributors to the US National Academy of

Sciences report, Postharvest Food Losses in Develop-

ing Countries, pointed out that to quantify food

losses to insects and other postharvest pests was vir-

tually impossible. They set 10% as an average min-

imum overall loss for cereals and legumes and 20% as

the minimum for perishables and fish. Because diets

in developing countries contain little, if any, dried or

INSECT PESTS/Problems Caused by Insects and Mites 3323

smoked red meat or poultry, no loss figures were

considered.

0002 In 1975, worldwide losses due to insects and

rodents were estimated by the Food and Agriculture

Organization (FAO) of the United Nations as about

20%. These figures ranged from about 10% in de-

veloped countries to 30% in African and Asian coun-

tries. However, in the literature, authoritative sources

often refer to losses of 50% in grain, with much of the

remainder so contaminated or damaged as to be

nearly worthless. Whether we will ever be able to

quantify the losses correctly may not be as important

as we believe. In any of the underdeveloped or

developing countries of the world there are instances

where pests have ruined entire storages; there is

clearly a need for correction.

0003 The effort to secure adequate loss data to estimate

worldwide losses requires a study of the continuum

from the farm to the consumer. This has proved to be

a major logistics problem in even the most developed

countries. In addition, social and cultural factors will

also limit the methods of preparation and utilization.

Politics will affect the storage, distribution, and avail-

ability. It requires a concerted effort on the part of all

levels of government and the consuming public to

insure an adequate supply of wholesome and nutri-

tious food and quality fiber.

0004 The seriousness of the postharvest losses has been

recognized by the United Nations. In 1975, the FAO

organized a conference on postharvest food losses.

This conference stressed the losses in the tropical

regions and established a goal of reducing postharvest

food losses by 50% by 1985. To achieve this goal it

was necessary to develop methods of loss assessment.

Neither goal has been reached as yet, but many im-

provements have been made in protecting harvested

foods during their movement from the farm to the

ultimate consumer.

Sites of Possible Food Losses

0005 Losses may occur at any point during the interim

between the harvest and gathering up to the point of

consumption. For the convenience of this discussion

this continuum will be broken into the following

intervals:

0006 Harvest – the separation of, or collection of, the

part of the plant to be utilized by humans or the

slaughter of animals.

0007 Initial processing – the separation of, or extraction

of, edible from nonedible, e.g., peeling of fruits

and vegetables, removing corn (maize) from the

cob, and other activities associated with cleaning,

drying, and grading, or cleaning and cutting-up of

animal carcasses.

0008Preservation – the prevention of loss and spoilage,

e.g., providing proper storage conditions and

facilities, drying to inhibit fungus growth, and the

use of pesticides to protect against insect attack.

0009Storage – the management of the storage facility,

e.g., protecting food from damage by moisture,

temperature, and pests through the use of aer-

ation, pesticides, refrigeration, controlled atmos-

pheres, etc.

0010Transportation – the use of all kinds of vehicles

and containers to move foods from point of pro-

duction to the point of final consumption.

0011Processing – the conversion of edible forms of

plant and animal products into another form

which is more acceptable or more convenient to

the consumer, e.g., reducing the fat content in

meats, packaging and canning fruits and vege-

tables, and quick-freezing raw and partially pre-

pared individual foods or even complete meals.

Industries at Special Risk

0012The loss of a food for any reason is significant to those

who suffered the loss. However, when losses are very

large and involve significantly large areas, such as

regions and countries, the economics and logistics of

supplying these areas with replacement food stocks

become a major problem which usually results in

suffering and starvation. In the underdeveloped coun-

tries and, to a somewhat lesser extent, in the developing

countries, the most important industry is farming.

0013The farmers must store sufficient food to feed

themselves and their families for about a year, and

produce enough surplus first, to sell in order to secure

needed staples and second, to meet their seeding

needs for the next cropping season. To some extent

farmers have to backstop themselves against cata-

strophic losses by joining in cooperative storages at

the village or other local levels. In many countries the

national governments have established programs of

food storage administered by departments or minis-

tries of food, agriculture, or supply. However, such

programs are dependent upon food production

within the country, or the availability of currency or

credit that will allow for importation in the event of

harvest shortfalls.

0014It is well documented that many pests attacking

stored products, particularly the grains and oilseeds,

first attack these seeds in the field. Similarly, it is also

known that many transportation vehicles and con-

tainers often harbor pests left from previous uses of

these vehicles and containers. While these insects and

mites are, without question, the source of many sub-

sequent infestations that arise in storage and process-

ing facilities, they are rarely, if ever, adequately

3324 INSECT PESTS/Problems Caused by Insects and Mites

controlled. Proper insect-resistant packaging and

intransit and static fumigation of ships, barges, rail-

cars, and containers are examples of procedures that

have helped to minimize the effect of residual insects

and mites in such vehicles. (See Cereals: Handling of

Grain for Storage; Fumigants.)

0015 In the continuum of food moving from the farm to

the ultimate consumer, there are two primary areas

where the industries involved in the interim can be at

special or high risk. These two areas are storage and

processing. While it is recognized that some firms

may well be involved in both storage and processing,

the two areas will be discussed separately.

Storage Industries

0016 It is in the industries that provide and maintain stor-

age facilities that those rather large losses due to pests

occur. In these facilities raw or partially processed

products are stored in bulk, providing a large, readily

available food supply for any pest that can gain entry.

In the case of insect and mite pests the process of

exclusion is often very difficult, or expensive, or

both. Fortunately, these pests are poikilothermic

(cold-blooded) and cannot adjust their body tempera-

tures from that of the environment. Therefore proper

regulation of the temperature and the moisture con-

tent of the commodity can be used to prevent any

incipient infestations from getting out of hand and

causing large amounts of damage. (See Storage Sta-

bility: Parameters Affecting Storage Stability.)

0017 The problems of providing proper storage and edu-

cating those responsible for managing such storage

have occupied an important place on the agenda of

international organizations such as the FAO, the

International Atomic Energy Agency (IAEA) and the

World Bank, as well as international consortiums

such as the Group for Assistance on Systems Relating

to Grain After Harvest (GASGA). Placing emphasis

on well-managed storage is, of course, a proper ap-

proach; logistics, transportation, and processing are

rather unimportant if there is nothing to move, dis-

tribute, or process. Storage is also the point at which

significant losses in both quantity and quality can

occur in developing countries, unless trained and

experienced personnel are responsible and alert to

such potential problems.

Processing Industries

0018 In the industries preparing and modifying foods for

increased acceptance and convenience, we rarely see

major losses in quantity of food products. However,

losses in quality will occur unless those responsible

for the actual processing are not constantly alert. The

loss in quality will usually come about through an

inspection or regulatory procedure, and will usually

be in the form of adulteration and contamination.

Most developing countries have regulations, sup-

ported by an inspection procedure that will establish

the quality of food produced as a result of processing.

Industry, to protect itself, develops good manufactur-

ing practices that, if followed, meet their country’s

regulations for clean, safe food.

0019Therefore it is essential for the maintenance of a

safe food industry that correct identifications of

insects and their related pests are readily available.

Such identifications must include all life stages – eggs,

larvae, pupae, and adults – found in both raw and

processed food. In fact, this need for rapid and accur-

ate identifications extends to fragments of insects

found in processed foods.

0020In the USA, this regulation of foods is found in the

Food and Drug Act (FDA). Regarding insects, mites,

and other pests, this law says that a food is adulter-

ated if it has been prepared, packed, or held under

conditions whereby it may have become contamin-

ated. The food inspected does not have to contain

pests. The FDA inspector noting excessive evidence

of insects will try to find the infested product, but

such a finding is not required for regulatory action.

(See Legislation: Contaminants and Adulterants.)

0021Processing industries may also confront another

regulatory process in many countries, that of plant

and animal quarantine. These laws are not promul-

gated to protect humans and their animals from adul-

terated foods but rather to prevent the importation of

pests that will affect the nation’s agriculture. How-

ever, these laws may impact upon the availability of a

product scheduled to be processed.

Problems and Control of Beetles and

Weevils

0022Beetles and weevils are most often thought of as pests

of grains and legume seeds. This is apparently due to

the large quantities of these seeds stored and our

heavy dependence upon them. However, they are

also major pests of roots and tubers, dried fruits and

nuts, and dried meats and other animal products. In

Table 1 is a listing of the major beetle and weevil pests

of these stored products.

0023The control of beetles and weevils has traditionally

been to maintain a low and uniform temperature and

moisture content throughout. Most insect and mite

pests have quite specific optimum temperatures for

activity and reproduction, and a lower level with

regard to moisture content of the product for sur-

vival. This optimum temperature is between 21 and



C, with minimum moisture content of 10–10.5%.

INSECT PESTS/Problems Caused by Insects and Mites 3325

At temperatures below 13–15



C reproduction is

severely limited in most species, and at lower

temperatures it is prohibited altogether.

0024 In conjunction with managing the storage environ-

ment there have been two approaches – preventive

and corrective – to the effective use of chemical pesti-

cides. The preventive approach has involved the use

of grain and oilseed protectants, residual pesticides

sprayed or dusted directly on to the seeds, or into

raw foods that have a legal tolerance for the pesti-

cides. Residuals will be applied most often into the

storage in the form of crack and crevice, spot or

general sprays or dusts, to prevent crawling pests

from reaching the product. Often a program of

periodic applications of insecticide fogs or aerosols

is used to supplement these residual pesticide applica-

tions. These fogs and aerosols are contact pesticides

and provide little, if any, residual, but provide excel-

lent control of exposed crawling and flying pests. (See

Pesticides and Herbicides: Residue Determination.)

0025The corrective approach involves the use of fumi-

gants, particularly when an infestation gets out of

hand, or when there is a need for a quick kill to

facilitate a sale or meet a quarantine requirement.

When a food requires this treatment, it is generally

the result of the preventive program being ineffective

as a result of some breakdown in the pest manage-

ment program.

0026There are several fumigants available throughout

the world, but many are now being phased out or

banned because of their adverse effect on humans or

the environment. Two fumigants, methyl bromide

and phosphine, are still readily available and used

throughout most of the world for the protection of

foods. Phosphine or hydrogen phosphide gas, a

product of atmospheric moisture reacting with a

metal phosphide to release the gas PH

, is the easiest

to use, readily available and leaves little, if any, resi-

due. It does require 3–5 days’ confinement, with the

product under ideal temperature conditions of 15–



C, and longer if the gas is to penetrate to depths

of 10–20 m without the assistance of a recirculation

system. Methyl bromide is still the fumigant of choice

when fumigations must be effected within 24 h or

less. It is also the fumigant of choice by most quaran-

tine agencies. However, methyl bromide has been

determined to be an ozone depleter and therefore is

considered to be detrimental to the earth’s protective

ozone layer (in an international treaty referred to as

the Montreal Protocol). Currently methyl bromide is

being phased out of production and use and most

probably will not be available as a fumigant in de-

veloped nations after the year 2005 and developing

nations after the year 2015.

0027The major problem in effecting satisfactory control

is the difficulty of detecting infestations of the weevils

and borers. Shortly after an infestation is established,

more than 95% of the population – larvae and pupae

– is hidden within the seeds. This results in a large

amount of damage for the small number of adults that

may be visible. It is therefore important to maintain

an effective surveillance and inspection program if

populations of these insect pests are to be managed

and damage is to be minimized.

Problems and Control of Moths

0028As with the beetles, moth pests of stored products are

also primarily pests of grains and legumes. However,

tbl0001 Table 1 Beetle and weevil pests of stored products

Pests of grain and legume seeds and their processed

products

Khapra beetle

(Trogoderma granarium)

Siamese grain weevil

(Lophocateres pusillus)

Larger grain borer

(Prostephenus truncatus)

Rusty grain beetle

(Cryptolestes ferrugineus)

Lesser grain borer

(Rhizopertha dominica)

Foreign grain beetle

(Ahasverus advena)

Cigarette beetle

(Lasioderma serricorne)

Longheaded flour beetle

(Latheticus oryzae)

Sawtoothed grain beetle

(Oryzaephilus surinamensis)

Broadhorned flour beetle

(Gnathocerus cornutus)

Merchant grain beetle

(Oryzaephilus mecator)

Drugstore beetle

(Stegobium paniceum)

Confused flour beetle

(Tribolium confusum)

Bean weevil

(Acanthoscelides obtectus)

Red flour beetle

(Tribolium castaneum)

Cowpea weevils

(Callosobruchus spp.)

Granary weevil

(Sitophilus granarius)

Pea and bean weevils

(Bruchus spp.)

Rice weevil

(S. oryzae)

Groundnut beetle

(Caryedon serratus)

Maize weevil

(S. zeamais)

Coffee bean weevil

(Araeceres fasciculatus)

Pests of roots and tubers

Powder-post beetles

(Lyc tus spp.)

Sweet potato weevils

(Cyclas spp.)

False powder-post beetles

(Bostrichid beetles)

Yam beetles

(Prionoryctes spp.)

Siamese grain beetle

(Lophocateres pusillus)

Broadnosed grain weevil

(Caulophilus oryzae)

Flat grain beetles

(Cryptolestes spp.)

Pests of dried fruit and nuts

Cigarette beetle

(Lasioderma serricorne)

Red flour beetle

(Tribolium castaneum)

Sap beetles

(Carpophilus spp.)

Nut weevils

(Curculio spp.)

Sawtoothed grain beetles

(Oryzaephilus surinamensis)

Pests of dried meats and other animal products

Hide beetles

(Dermestes spp.)

Carpet beetles

(Anthrenus spp.)

Carpet beetles

(Attagenus spp.)

Ham and copra beetle

(Necrobia spp.)

3326 INSECT PESTS/Problems Caused by Insects and Mites

they are major pests of dried fruits and animal prod-

ucts. In Table 2 is a listing of the major moth pests

by commodity groupings. (See Legumes: Legumes in

the Diet.)

0029 The control of moths in storage situations is

effected in much the same way as the control of

beetles and weevils. Their presence is readily recog-

nized by the presence of flying adults. The larvae of

the moths, the caterpillars, do not penetrate deeply

into the stored product and usually are found feeding

close to the surface. The larvae trail out a dragline of

silk as they move about. In very heavy infestations

these silk lines can coalesce and form a cover over the

surface like a tarpaulin and even affect the penetra-

tion of fumigant gases. However, when any amount

of silk occurs it is the result of a neglected or misman-

aged situation. One pest, the Angoumois grain moth,

has a behavior somewhat similar to that of weevils. It

often infests the grain in the field, and the larvae mine

inside the seed, making it difficult to assess the popu-

lation. The adults of the moths do not feed; the larvae

cause all the damage.

0030 Today the monitoring for infestation of moths is

made much easier by the use of pheromones and

traps. However, their acceptance by warehouse staff

has been slow because of the low dollar value per unit

of raw commodity stored. There also remain some

questions as to how to space these traps in a ware-

house and exactly what the catch means. It is only a

matter of time before these questions are answered, at

least for our major commodity groups.

Problems and Control of Mites

0031Mites are not primary pests of most foods, except

possibly for crops such as mushrooms and cheeses,

and similar products associated with fungi and fer-

mentation. There are relatively few mites of import-

ance to foods, but those that do attack often cause

very serious problems and great loss of product. In

Table 3 is a list of some of the major mite pests

occurring in foods. (See Spoilage: Yeasts in Spoilage.)

0032When mite infestation occurs, it is usually the result

of unfavorable storage conditions. Mite populations

flourish in cool, moist environments which are also

conducive to the growth of fungi and yeasts. Under

these conditions, the mites feed on both the fungi and

yeast and on the substrata that have been prepared by

these fungi and yeasts. The fungi and yeast break

down the seed coat on the grain and the legumes,

and moisten or otherwise prepare the food for the

mite to feed on.

0033The control of mites is largely one of correcting the

environmental conditions so that it is unfavorable for

the mites. The use of residual pesticides is usually

ineffective because the fungi, yeasts, and moisture

degrade the pesticides. Residues on adjacent surfaces,

e.g., walls and floors, are quite ineffective, as the

mites are small; they move slowly and rarely, if

ever, encounter these surfaces. The use of fumigants

is effective, but they may not always be legally

used on the food product involved. Some success has

been achieved by use of high temperatures, above



C, but some foods may not accept such high

temperatures.

Past, Present, and Future of Insect Pest

Control

0034Pest control methodology can be found in the ancient

writings of biblical times. Grain was stored in sealed

tbl0002 Table 2 Moth pests of stored products

Moth pests of grain and legume seeds and their processed

products

Almond moth

(Cadra cautella)

Meal moth

(Pyralis farinalis)

Indianmeal moth

(Plodia interpunctella)

Rice moth

(Corcyra cephalonica)

Angoumois grain moth

(Sitotroga cerealella)

Mediterranean flour moth

(Ephestia kuehniella)

Tobacco moth

(Ephestia elutella)

Pink bollworm

(Pectinophora gossypiella)

Moth pests of roots and tubers

Potato tuber moth

(Phathorimaea operculella)

Gray pyralid

(Pyralis manihotalis)

Moth pests of dried fruits and nuts

Almond moth

(Cadra cautella)

Hickory shuckworm

(Lespeyresia caryana)

Dried fruit moth

(Ephestia calidella)

Naval orangeworm

(Paramyelois transitella)

Raisin moth

(Ephestia figulilella)

Indianmeal moth

(Plodia interpunctella)

Moth pests of dried meats and other animal products

Gray pyralid

(Pyralis manihotalis)

White-shouldered house moth

(Endrosis sarcitrella)

Case-bearing clothes moth

(Tinea pellionella)

Brown house moth

(Hofmannophila pseudospretella)

Common clothes moth

(Tineola bisselliella)

tbl0003Table 3 Mite pests of stored products

Mite pests of grain and legume and their processed

products

Flour mite (Acarus siro) Suidasia nesbitti

Grain mite (Glycyphagus destructor) Calogylyphus rhizoglyphoides

Tyrophagus longior

Mite pests of dried fruits and nuts

Flour mite (Acarus siro) Carpoglyphus lactis

Mite pests of dried meats and other animal products

Flour mite (Acarus siro) Cheesemite (Tyrophagus

casei)

Lardoglyphus konoi

INSECT PESTS/Problems Caused by Insects and Mites 3327

jars, providing a lethal atmosphere devoid of oxygen

and high in carbon dioxide, or grain was treated with

abrasive minerals or diatomaceous earth or fumi-

gated by sulfur dioxide produced by burning sulfur.

During the last century dependence has also been on

the arsenicals and botanicals and several fumigant

gases. Since World War II, we have been heavily

dependent upon chemicals, e.g., chloronated hydo-

carbons, organophosphates, carbamates, and pyreth-

roids. We have now learnt that the effects of these

chemicals on the environment and their efficacy for

insect control have been counterproductive to our

goals for a quality of life.

0035 During the last 30–40 years our research efforts

have been ever-increasing in the search to protect

our food, feed, seed, and fiber by better detection

and damage assessment and the implementation of

programmes of integrated pest control. Integrated

pest control is described as including an integration

of pest control tactics that emphasize the prevention

and avoidance of pest problems and meet economic,

public health, and environmental goals.

0036 The following list describes some pest control

tactics of the present and future for possible use in

integrated pest control:

0037 Modified atmospheres – the use of reduced

oxygen concentration by the addition of carbon

dioxide, nitrogen, or combustion gases.

0038 Gamma-radiation – the use of ionizing electro-

magnetic energy, which causes cell and tissue

damage.

0039 Accelerated electrons – the use of high-speed elec-

trons, which upon impact destroy cells and tissues.

0040 Hermetic storage – the sealing of a food in a

container so that natural respiration of the food

and any pests present will reduce the oxygen

content to a level that will not sustain life.

0041 Parasites and predators – the addition of insect

parasites and predators to raw commodities to

control the pest feeding on the food.

0042 Insect pathogens – the use of bacteria, viruses, and

fungi that naturally attack the pests of foods but

are not harmful to humans or animals.

0043 Temperature – the use of high or low tempera-

tures, including infrared and microwave radi-

ations.

0044 Genetic engineering – the insertion of a gene that

produces a material that is toxic to the insect pests

but not to other animals.

0045The safe and responsible use of chemical insecti-

cides and acaricides in combination with other

pest control tactics. (See Chill Foods: Effect of

Modified-atmosphere Packaging on Food Quality;

Irradiation of Foods: Basic Principles.)

See also: Cereals: Handling of Grain for Storage; Chilled

Storage: Use of Modified-atmosphere Packaging;

Fumigants; Irradiation of Foods: Basic Principles;

Legislation: Contaminants and Adulterants; Legumes:

Legumes in the Diet; Pesticides and Herbicides:

Residue Determination; Spoilage: Yeasts in Spoilage;

Storage Stability: Parameters Affecting Storage Stability