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Chapter 10 BASIC ENTOMOLOGY

IDAHO MASTER GARDENER UNIVERSITY OF IDAHO EXTENSION

I. Introduction 2 VI. Other -Like Creatures 9 II. Insect Anatomy 2 A. Mites, , Ticks, III. Insect Development 3 and —Arachnida 9 IV. Insect Classification 3 B. —Diploda 10 C. —Chilopoda 10 V. Major Orders of 4 D. Sowbugs and Pillbugs—Crustacea 10 A. Beetles and Weevils—Coleoptera 4 E. Garden or Symphylan— B. and — Symphla 10 5 Further Reading 10 C. , Mosquitoes, Gnats, Midges— Diptera 5 D. , , , , etc.— 6 E. True Bugs—Hemiptera 6 F. Aphids, Scales, Leafhoppers, Cicadas—Homoptera 7 G. Grasshoppers, Crickets, Cockroaches, Camel Crickets—Orthoptera 7 H. Termites—Isoptera 8 I. Earwigs—Dermaptera 8 J. Thrips—Thysanoptera 8 K. and Firebrats— Thysanura 9 L. Springtails—Collembolla 9 M.Other Orders 9

CHAPTER 10 IDAHO MASTER GARDENER PROGRAM HANDBOOK 10 - 1 Chapter 10 Basic Entomology

Vickie J. Parker-Clark, Former District I Extension Director, Coeur d’Alene

I. Introduction meter long, and some of the larger long-horned The kingdom contains many distinct beetles that are as much as 6 inches long. groups called phyla. Each phylum is divided Except for a few common structural features, in- into a number of classes. The insects are in the sects are also variable in appearance. Some class Insecta (or —“six feet”) within have bizarre horns and spines, while others the phylum Arthropoda (jointed foot). The in- may resemble dead leaves. Some insects are sect class is further divided into orders, fami- quite attractive like the , but “beauti- lies, genera, and finally, species. ful” is hardly the word for a cockroach. Approximately 1 million species of insects have All of this makes insects a fascinating group to been identified to date. The greatest numbers investigate, but it also makes the study of in- of these species belong to the beetle, , and sects and their classification somewhat com- -- groups. We generally associate plex. It is important to learn the main differ- insects with crop loss or disease transmission; ences among insects, so that we can distin- however, insects fulfill a useful function in our guish one group from another. Then we can environment. suggest adequate control procedures and give Only a small percentage of insects are considered quality management suggestions. pests of humans and of their , crops, or II. Insect Anatomy fiber. However, this small number can cause serious crop losses, or transmit serious dis- Insects are animals, however, unlike many ani- eases to humans or animals. mals, they have no backbones. They have an outer skeleton () instead of the in- Most insects appear to be beneficial or harmless. ner skeleton (endoskeleton) of most large ani- Many are predators, such as lady beetles, mals. The following characteristics separate which live by feeding on pestiferous aphids. insects from other animals (Fig. 1). Others are parasitic, such as the wasps. Still others, such as honey bees, act as Fig. 1. Parts of an insect. pollinators of crops and also pro- thorax vide us with honey. Many insects wings are responsible for the decomposi- tion of plant and animal matter. A head good example is the carpenter ant. Obviously, when it is attacking the timber of our home it is a pest, abdomen however, when it is in the forest mining the wood of old, fallen trees, it is part of nature’s recycling program. mouthparts Size is quite variable throughout the insect world. The extremes include tiny wasps that are less than a milli- legs

10 - 2 BASIC ENTOMOLOGY CHAPTER 10 A.Insects have three body regions—Head, tho- tivities much, you will often hear the phrase rax, and abdomen. “keying out.” This simply means identifying B. Many adult insects have wings, and insects the insect (see MS 109 in “Further Reading”). are the only flying invertebrates. B. Insects are also classified by the type of C. Adults possess three pairs of legs, all lo- damage they cause. Some examples include cated on the thorax. “root maggot,” “twig girdler,” or “crown borer.” Destructive insect activities help III. Insect Development narrow down the multitude of possible iden- All insects change during growth by a process tities and often make insect identification called metamorphosis (Fig. 2). Insect near- quicker and simpler. relatives such as spiders, mites, and centipedes C. Some insects can be categorized as preda- also undergo metamorphosis. tors or parasites. Predators and parasites ac- The more highly developed insects make the count for much of the reduction of pest in- most complete changes. Beetles, moths, butter- sect populations in nature, and, for this rea- flies, wasps, and ants all go through four son, are also called beneficials (see PNW stages. These are the egg, , pupa, and 343 in “Further Reading”). adult. The larva is usually the damaging stage, Beneficials can be useful, but they usually although adult feeding can be destructive. need some cultural encouragement. Their Also, it is not unusual for the larval and adult use requires careful crop management and a stages of a species to feed on different hosts or degree of tolerance for some crop loss. different parts of the host. The pupa is a 1. Predators kill and feed on their prey; they nonfeeding stage; in most cases it is also very are generally larger than their prey. inactive. 2. Parasites are usually smaller and often The lower forms or less-developed kinds of in- weaker than their prey; they gradually sects change only slightly during metamorpho- kill by injecting eggs that develop on, sis. True bugs, aphids, grasshoppers, termites, within, or near the insect over a period of earwigs, stoneflies, etc., go through only three time. They may sting and paralyze their stages. These stages are the egg, nymph, and prey in order to stock their nests with adult. Except for size, the nymph and adult food for the developing larvae or eggs. closely resemble each other. The major differ- The immature parasites will then con- ence is the lack of fully formed wings in the sume the paralyzed insect at their leisure. nymph. The nymph and adult generally feed D.Another form of categorization is by feed- on the same host or host parts. ing mechanism or mouthpart. The broadest IV. Insect Classification grouping is defined by chewing or sucking There are several methods of separating or cat- mouthparts (Fig. 3). egorizing insects. Fig. 3. Insect feeding mechanisms. A.The professional uses body parts for identi- Chewing type Sucking type fication and observes differences in these parts through a microscope. He or she tracks down an insect’s identity by using a written insect “key.” The anatomy of an insect will place it into a specific insect group called an order. If you are around entomological ac-

Fig. 2. Metamorphosis stages in insects. adult adult

pupa egg nymph egg

larva Gradual or Complete metamorphosis incomplete metamorphosis Mandibles Sucking tube

CHAPTER 10 IDAHO MASTER GARDENER PROGRAM HANDBOOK 10 - 3 Although this manner of separation is some- butterflies—Lepidoptera; flies—Diptera; bees, what helpful for identification, its greatest ants, wasps, hornets—Hymenoptera; true bugs, value is in determining if a certain kind of such as stink bugs—Hemiptera; aphids, scales, will work. For example, systemic and leafhoppers—Homoptera; grasshoppers, insecticides “generally” do not work as well crickets, and cockroaches—Orthoptera; ter- on chewing insects as on sucking insects. mites—Isoptera; earwigs—Dermaptera. There Proper identification is extremely important. are many other insect orders, but these are rep- If a beneficial insect or a nondamaging in- resentatives of economic importance. sect is improperly identified as a pest, a pes- Separating groups of insects may be quite diffi- ticide application will usually disrupt a cult unless you have closely studied examples natural control agent. The disruption of this of the various types. It is important to recog- beneficial’s activity may induce the need for nize the structural characteristics that distin- the chemical. Chances are you may have guish one insect from another (see “Further made an application that did no more for Reading”). Use all of the characteristics listed you than cost you money. in Table 1 to distinguish each order. A.Beetles and Weevils—Coleoptera Note: Do not make recommendations based Some of the typical beetles that you may see on the verbal description of a pest by a are long-horned beetles and flatheaded bor- client. Too many misidentifications are ers that bore into trees, logs, and lumber. made this way, and wrong identifica- These beetles are variable in color. Long- tion leads to ineffective control mea- horned beetles usually have long antennae sures and unnecessary expense or and are strong fliers. Lady beetles are about problems. Insist on seeing the pest, or 1/4-inch long and are usually red or orange, at least its damage, before you volun- generally with spots. Lady beetles are ben- teer anything. eficial as larvae and adults, since they feed on aphids and other soft-bodied insect and V. Major Orders of Insects mite pests. Some other common beetles are Major insect groupings under the class level are the pea weevil, an important pest of peas, called orders. Some representatives that you and click beetles, whose larvae are known will see are: beetles—Coleoptera; moths and to some of you as wireworms.

Table 1. Major order of insects. Name of order Common examples Wings/mouthparts Coleoptera Beetles, weevils 2 pairs wings or wingless; chewing Lepidoptera Moths, butterflies 2 pairs wings; chewing (larvae), sucking, or siphoning (adults) Diptera Mosquitoes, flies, and gnats 1 pair wings; chewing (larvae), piercing-sucking, or sponging (adults) Hymenoptera Wasps, bees, ants, and sawflies 2 pairs wings or wingless; chewing Hemiptera Bed bugs, stink bugs, and cinch bugs 2 pairs wings; piercing-sucking Homoptera Aphids, leafhoppers, scales, mealybugs 2 pairs wings or wingless; piercing-sucking Orthoptera Grasshoppers, crickets, and cockroaches 2 pairs wings or wingless; chewing Isoptera Termites 2 pairs wings or wingless; chewing Dermaptera Earwigs 2 pairs wings or wingless; chewing Thysanura Silverfish, firebrats Wingless; chewing Thysanoptera Thrips 2 pairs wings or wingless; rasping-sucking Collembola Springtails Wingless; chewing Psocoptera Barklice, booklice 2 pairs wings or wingless; chewing Mallophaga Chewing lice Wingless; chewing Anoplura Sucking lice 2 pairs wings or wingless; piercing-sucking Siphonaptera Wingless; chewing (larvae), piercing-sucking (adults)

10 - 4 BASIC ENTOMOLOGY CHAPTER 10 1. Adults have a hardened, horny outer skel- Another Lepidoteran is the codling , eton. which does damage to apples. The peach 2. Adults have two pairs of wings; the outer twig borer is a severe pest of peaches, pair is hardened, and the inner pair mem- prunes, plums, and apricots. branous. 1. Adults are soft-bodied with four well- developed, membranous wings covered Note: A few beetles are practically wingless, with small scales. and some have only an outer hard pair 2. Adult mouthparts consist of a coiled, of wings. sucking tube; adults feed on and other liquids. 3. Beetles have chewing mouthparts. 3. The larvae are caterpillars that are worm- 4. Adults usually develop noticeable anten- like, and variable in color; they are vora- nae. cious feeders. 5. Coleoptera larvae have a head capsule 4. The larvae have chewing mouthparts. and three pairs of legs on the abdomen. 5. The larvae have true legs on the thorax and a variable number of prolegs on the Note: Weevil larvae lack legs on the thorax. abdomen. 6. Both beetles and weevils go through a 6. Lepidopterans undergo complete meta- complete metamorphosis as in Fig. 4. morphosis as in Fig. 5. 7. Some authorities consider the beetles to C. Flies, Mosquitoes, Gnats, Midges—Diptera be the largest group or order of insects in Flies are an important group in terms of nature. their medical effects on humans and ani- B. Moths and Butterflies—Lepidoptera mals. Some, such as bot flies, are parasites as immatures on mammals. Some flies, such The moth and butterfly group has several as the face fly, disrupt or annoy livestock, damaging members. Cutworms damage causing the cows or other animals to stop many crops. For example, corn earworm feeding. Fly maggots or larvae are generally larvae, which are greenish or tannish with found in manure or other decaying matter. some stripes and about 1 1/4-inch long when fully grown, cause severe damage to The flies most commonly encountered are corn and attack a variety of vegetables. the housefly, the lesser house fly, and the face fly. The grayish adults infest homes, , celery, and cabbage loopers have poultry houses, and livestock. The house fly injurious larvae. They are often known as has been suspected of mechanically trans- measuring worms because of their looping mitting such diseases as polio to food sur- action, which gives the impression that they faces. are measuring the plant on which they are feeding. Fig. 5. Metamorphosis of a moth. Fig. 4. Metamorphosis of a beetle.

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CHAPTER 10 IDAHO MASTER GARDENER PROGRAM HANDBOOK 10 - 5 Commercial agricultural insect pests in this 1. Pear slug—The adult is black with yel- order include the cherry fruit fly, walnut low markings. The larva is small, slug- husk fly, onion and cabbage maggot, and like, and feeds on leaves of pear, cherry, carrot rust fly. Others are often disease vec- and plum. tors, such as mosquitoes or deerflies. Vec- 2. Yellowjackets—The adults have black tors can transmit such diseases as malaria. and yellow markings. They build nests in Mosquitoes are small, slender, long-legged, the ground, or papery structures on trees frail flies. The larvae are elongate and live or under eaves. Their stings are painful in water. The adult female is the injurious and dangerous if you are allergic to them. stage. She feeds by sucking human and live- Many species are beneficial predators. stock blood by piercing the skin with her 3. Leafcutting bees—These are small- to long stiletto-like mouthparts. medium-sized bees, variable in color. 1. Adults have only one pair of wings and They are noted for their long tongues. are rather soft-bodied and hairy. One species is an excellent alfalfa polli- 2. Adults have sponging (house fly) or nator. Leafcutters may defoliate some piercing (mosquito) mouthparts. trees and shrubs. 3. Diptera larvae may have mouth hooks or 4. Common ants—Several ants, such as the chewing mouthparts. carpenter ants and the house ants (includ- 4. Most larvae are legless. ing the pavement ant and odorous house ant), are in this group. Many are benefi- 5. The larvae of advanced forms, such as cial predators or decomposers. the house fly and relatives, have no head capsule, possess mouth hooks, and are a. The adults have two pairs of membra- called maggots. Lower forms such as nous wings. mosquito larvae and relatives have a head b. The adults generally have chewing capsule. mouthparts. 6. Diptera undergo complete metamorpho- c. The adults are rather soft-bodied or sis as in Fig. 6. have slightly hardened bodies. D.Bees, Wasps, Ants, Sawflies, etc.— d. The larvae have no legs (wasps, bees, Hymenoptera ants) or have legs on the thorax and This group is a large one. Many of its mem- the abdomen (some sawflies). bers are important pollinators of agricultural 5. Hymenoptera undergo complete meta- crops, such as the honeybee, leafcutter bee, morphosis as in Fig. 7. and alkali bee. Some are important preda- E. True Bugs—Hemiptera tors, parasites, and scavengers; others are Consperse stink bug—A gray or brownish injurious to humans and their crops. plant bug that is shield shaped. The stink bug feeds on many fruits and vegetables.

Fig. 6. Metamorphosis of a fly. Fig. 7. Metamorphosis of an ant.

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10 - 6 BASIC ENTOMOLOGY CHAPTER 10 1. Boxelder bug—This bug is gray-brown including the green peach aphid, which to black with red lines on the under sur- carries the leaf roll virus of potatoes and face and on the lower portion of the outer sugarbeets. The rose aphid, both green wings. It feeds primarily on boxelder and and brown forms, are found on many or- can invade homes in early summer or namentals. Apple aphids, and green, rosy, fall. and woolly aphids all cause severe dam- 2. Lygus bug—These bugs are greenish, or age to apples. brownish black and occasionally yellow- 2. Scales—Scale insects are usually quite ish or gray; they are rather slim plant small and are usually circular or football- bugs about 1/4-inch long. The head is shaped. During most of their life cycle, blotched with black. They are probably they are protected by a hardened scale the most injurious bugs of seed crops in covering. San Jose scale is a pest of many the United States. fruit trees and ornamentals. Oyster shell a. The adults have two pairs of wings; scale is a brown cornucopia-shaped scale the second pair is membranous, the (horn of plenty) found on ornamental first pair is membranous and thickened trees and shrubs. Lecanium scale is a on the basal half. The nymphs are not large, brown, hemispherical-shaped scale fully formed and are called “wing found on trees and woody plants of sev- pads.” eral types. b. Adults and nymphs usually resemble a. These insects are generally small and one another. soft-bodied, though cicadas are larger c. True bugs have piercing-sucking and hard-bodied. mouthparts. b. Members may be winged or wingless. d. Adults and nymphs both are damaging c. All stages have sucking mouthparts. stages. d. Many members are carriers of plant e. True bugs have a gradual metamor- pathogens. phosis (Fig. 8). The stages are egg, e. Homopterans have a gradual metamor- nymph, and adult. phosis as the aphid in Fig. 9. F. Aphids, Scales, Leafhoppers, Cicadas— G.Grasshoppers, Crickets, Cockroaches, Homoptera Camel Crickets—Orthoptera 1. Aphid—There are many types, sizes, and Some examples of grasshoppers and their shapes of aphids. The giant willow aphid allies are migratory and two-striped grass- is a large, black species. The pea aphid is hoppers and the red-legged grasshopper. a rather large, green species found on al- These are damaging pests of crops and falfa, peas, clover, sweet clover, and rangeland. The camel cricket, the Jerusalem other herbaceous legumes. It may also be cricket, and the German roach are also com- pinkish in color. Several species of monly encountered. Crickets also can dam- aphids attack vegetable and tree crops, age crops. The German cockroach is a met- ropolitan pest. Fig. 8. Metamorphosis of a bug. 1. Adults are moderate to large and are of- ten rather hard-bodied.

Fig. 9. Metamorphosis of an aphid. ; ; ; ;

CHAPTER 10 IDAHO MASTER GARDENER PROGRAM HANDBOOK 10 - 7 Fig. 10. Metamorphosis of a grasshopper. Fig. 11. Metamorphosis of a termite.

; ; ;; 2. Adults usually have two pairs of wings. The forewings are elongated, narrow, and leathery; the second pair of wings are membranous with an extensive folded area. 3. Adults and nymphs have chewing mouth- ornamentals, small trees, and houses parts and are damaging. throughout the state of Idaho, but it may also be beneficial since it often preys upon 4. The hind legs of forms other than cock- other insects. roaches and walking sticks are enlarged for jumping. 1. Adults are moderately sized. 5. Immature stages are called nymphs and, 2. They have chewing mouthparts. except for being wingless, resemble 3. Earwigs are elongated, flattened and have adults. strong, movable forceps on the rear end. 6. Orthopterans have a simple metamorpho- 4. They have short, hardened outer wings sis as in Fig. 10. and cover folded, membranous inner H.Termites—Isoptera wings. The injurious termites are generally placed 5. Earwigs have a gradual metamorphosis in two groups: the dampwood and subterra- (Fig. 12). nean types. Both feed on wood and wood J. Thrips—Thysanoptera products. The dampwood types are usually 1. Thrips are small with sucking mouthparts not primary feeders on sound wood in build- that are assisted by a single mandible that ings, while the subterranean types are found aids in rasping the plant tissue. in large numbers in sound structures where 2. Wings may be present or absent. If they may do considerable damage if not de- present, they are long and narrow and tected early and controlled quickly. Colo- fringed with long hairs. nies of the subterranean type must have a 3. Many feed on ornamentals and some on connection with soil to obtain moisture. vegetable crops such as peas and onions. 1. These are so-called “white ants.” Many are predators on other insects. A 2. Termites are distinguished from true few species bite humans. ants by their thick “waists” and their 4. Thrips have a gradual metamorphosis. white or light brown color. 3. Termites have thin, straight antennae; Fig. 12. Metamorphosis of an earwig. ants have elbowed antennae. 4. Termites have chewing mouthparts. 5. They possess many forms or castes such a worker, soldier, and queen. ; ; 6. Termites have a gradual metamorpho- sis as in Fig. 11. I. Earwigs—Dermaptera The European earwig is our only species of earwig. It is occasionally a pest of gardens,

10 - 8 BASIC ENTOMOLOGY CHAPTER 10 K.Silverfish and Firebrats—Thysanura many of which are beneficial predators; 1. Group members have chewing mouth- book or bark lice—Psocoptera, basically parts. scavengers, but with some species that are 2. Thysanura is one of the few insect orders stored-products pests; animal lice and suck- whose members do not possess wings. ing lice—Anaplura; and chewing lice— Mallophaga. 3. These insects have bristles on the tip of the abdomen. VI. Other Insect-Like Creatures 4. They are household pests and feed on Several noninsect pests may be found in the such items as paste, paper, and crumbs. field and home and include those listed in 5. They have a gradual metamorphosis. Table 2. L. Springtails—Collembolla A.Spider Mites, Spiders, Ticks, and 1. Springtails are minute insects with chew- Scorpions—Arachnida ing or piercing mouthparts. 1. Spider mites—These tiny, soft-bodied 2. They possess an appendage on their ven- animals have two body regions, thick tral (under) side; it operates as a spring to waists, four pairs of legs, and are without aid the insect in quick escape. antennae. Common species include the 3. These insects are abundant in moist following. areas, hence the reference to “moving a. The two-spotted spider mite and its piles of soot” in backyards during the near relatives, the Pacific, Atlantic, wetter seasons. and McDaniel spider mites. These 4. They feed on decaying organic material mites have two spots on the back and primarily but will on occasion attack have tail-end spots in some species. plants, particularly in greenhouses. They may be clear, green, orange, or 5. Springtails undergo a gradual metamor- red. They are usually hard to observe phosis. without a hand lens. M. Other Orders b. European red mite: This mite is car- mine red with white spines. Many other insect orders are of no real con- cern in the home garden. Some of the more c. Brown mite and the clover mite: These common ones are stoneflies—Plecoptera; mites are brownish or grayish, flat, and caddisflies—Trichoptera; and have very long front legs. damsel flies—Odonata; and mayflies— 2. Spiders—Spiders resemble mites except Ephemeroptera. These orders are all associ- that most are larger and the two body re- ated with aquatic habitats. gions are more clearly distinct from one Some others you should be aware of include another (thin waist). Most spiders are the nerve-winged insects—Neuroptera, beneficial predators. Common pest spe- cies include: Table 2. Noninsect pests. Class Example Description Arachnida Spiders, ticks, mites, scorpions 4 pairs legs; 2 body regions—cephalothorax and abdomen; no antennae; chewing or sucking mouthparts Chilopoda Centipedes 15 or more pairs of legs with only 1 pair of legs per body segment; 1 pair of antennae; 2 body regions—head and trunk; body flattened; chewing mouthparts; fast moving Diplopoda Millipedes 2 pairs of legs per apparent body segment; 1 pair of antennae; 2 body regions—head, trunk; body rounded; chewing mouthparts; slow moving Crustacea Sowbugs, pillbugs 1 pair of legs per body segment; 1 pair of antennae; 2 body regions— head and trunk; chewing mouthparts; roll into ball when disturbed Symphla Symphylan, garden centipede 11 or 12 pairs of short legs; centipedelike animals

CHAPTER 10 IDAHO MASTER GARDENER PROGRAM HANDBOOK 10 - 9 a. Black widow spider: Shy and likes D. Sowbugs and Pillbugs—Crustacea dank, dark places. This spider spins a Sowbugs are highly dependent on mois- characteristically messy web. It is nor- ture, which accounts for their common as- mally a shiny black, moderately sized sociation with damp habitats. Generally, spider with a reddish or orange hour- they feed on decaying plant material, but glass marking on the underside of the they will attack young plants in green- abdomen. Males and immature fe- houses and gardens. They are oval with a males can have stripes of red, yellow, hard convex outer shell made up of a num- and black on the abdomen. ber of plates. b. The hobo spider, sometimes called the E. Garden Centipede or Symphylan— aggressive house spider: Is a common Symphla light brown spider that is often found Members of this group resemble tiny centi- in basements. This spider has a pain- pedes. Generally, they are a pest of veg- less bite, but sometimes the skin etables and found in damp soils rich in or- sloughs off in the bite area. ganic matter. c. The brown recluse spider: A poisonous spider which, fortunately, does not oc- cur in the Pacific Northwest, however, Further Reading it is a potential threat. It is often con- fused with harmless wolf spiders and CDs, Booklets, and Pamphlets other hunting spiders. The brown re- cluse spider can be recognized easily University of Idaho Extension by a distinct, brown “fiddle case” on a PNW 343 Beneficial Organisms Associated with light brown or grayish background. Pacific Northwest Crops 3. Ticks—Ticks resemble large mites and PNW 186 Cockroaches are important in agriculture and medi- PNW 550 Encouraging Beneficial Insects in Your cine. They are parasites of humans and Garden animals. CD 1 Identification Keys for Insect Pests in B. Millipedes—Diploda Pacific Northwest Field Crops (CD- Millipedes are generally inoffensive crea- ROM) tures that feed on fungi and decaying plant MS 109 Keys to Damaging Stages of Insects material. At times, they can be fairly de- Commonly Attacking Field Crops in the structive to vegetables or other plants in Pacific Northwest greenhouses. They are elongate inverte- CIS 414 Spiders and Their Relatives brates with two visible body regions: a head and a body. They generally are rounded in cross section. With the excep- tion of the first four or five segments, all of the body segments possess two pairs of legs. They are relatively slow moving. C. Centipedes—Chilopoda Centipedes strongly resemble millipedes. They are different in that they have longer antennae, are flattened in cross section, have only one pair of legs on each body segment, and move rapidly. They are ben- eficial because they prey on other .

10 - 10 BASIC ENTOMOLOGY CHAPTER 10