entomology 3rd ed - c.gillott

Entomolog
y
Entomology
Th
ir
d
E
d
i
t
i
o
n
Entomo
l
og
y
Entomo
l
og
y
Th
ir
d
E
d
i
t
i
on
C

e
d
ric Gi
ll
ot
t
Universit
y
of Saskatchewa
n
S
askatoon, Saskatchewan, Canada
A
C.I.P. Cata
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g
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eL
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Printed in the Netherlands
.
C
ontents

Preface
.

xv
A
cknowledgment
s

x
vi
i
I
. Evolution and Diversit
y
1
A
rthro
p
o
d
Evolutio
n
1. Intro
d
uct
i
on
.

3

2. Art
h
ropo
d
D
i
vers
i
t
y

3
2
.1. On
y
chophora, Tardi
g
rada, and Pentastoma
.
4
2.
2
.
Trilobit
a

5
2
.3. The Chelicerate Arthro
p

ods
.

6
2
.4. T
h
e Man
dib
u
l
ate Art
h
ropo
ds

8
3. Evo
l
ut
i
onary Re
l
at
i
ons
hi
ps o
f
Art

h
ropo
d
s
.
1
4
3
.1. The Proble
m
14
3
.2. Theories of Arthro
p
od Evolutio
n
.
15
3
.2.1. Mono- and Diphyletic Theorie
s
.
1
5
3
.2.2. T
h
ePo
l
yp

h
y
l
et
i
cT
h
eor
y
17
3
.3. T
h
eUn
i
ram
i
an
s
.
2
0
3
.3.1. M
y
riapoda-Hexapoda Relationships 2
0
4
.
S

ummar
y
21
5
. Literature
22
2
In
sec
t
Di
vers
i
t
y
1. Intro
d
uct
i
on
.
2
5
2. Pr
i
m
i
t
i
ve W

i
n
gl
ess Insects
.
.
2
5
3. Evolution of Win
g
ed Insects
.
27
3.1. Ori
g
in and Evolution of Win
gs
2
7
3.2. P
h
y
l
ogenet
i
cRe
l
at
i
ons

hi
ps o
f
t
h
e Pterygota 3
3
3.3. Or
i
g
i
nan
d
Funct
i
ons o
f
t
h
e Pup
a
.
4
4
4
.T
h
e Success o
f
Insects 4

7
4
.1. The Adaptabilit
y
of Insect
s
47
4
.2. The Importance of Environmental Chan
g
es 49
v
vi
C
ontents
5
. Summar
y

5
3
6
. Literatur
e
53
3
E
xterna
l
S

tructur
e
1.
Introductio
n
5
7
2
. General Bod
y
Plan
.

57
3
.T
h
e Hea
d

60
3
.1.
G
enera
lS
tructure
.

60

3
.2. Hea
d
Appen
d
a
g
es
.

6
4
3
.
2
.
1
. Antenna
e

64
3.2.2. Mouth
p
arts .
.

6
4
4
.T

h
e Nec
k
an
d
T
h
orax
.
7
2
4.1. T
h
e Nec
k
7
3
4.2. Structure o
f
t
h
eT
h
ora
x
.
73
4.3. Thoracic Appenda
g
es

.
7
5
4
.
3
.
1
.Le
g
s 7
5
4
.3.2. W
i
ng
s
.
79
5
. The Abdomen
.

83
5
.1. General Structure
.
83
5.2. Abdominal Appenda
g

es
84
5
.2.1. External Genitalia 85
5
.2.2. Other Appendages
88
6
. Literatur
e
8
9
4
S
ystematics
a
nd
T
axonomy
1
. Intro
d
uct
i
o
n

91
2
. Nam

i
ng an
d
Descr
ibi
ng Insects
.

92
3
.C
l
ass
ifi
cat
i
o
n
.

94
3
.1. The Histor
y
of Insect Classification 9
6
4.
Identificatio
n
.

102
4.1. Key to t
h
eOr
d
ers o
f
Insect
s
1
03
5
. Literatur
e
111
5
A
ptery
g
ot
e
H
exapo
d
s
1
. Intro
d
uct

i
o
n
11
3
2
.Co
ll
em
b
o
l
a 114
3
. Protura
118
4
.Di
p
lur
a
.

120
5. Microcoryphia
.
12
2
6
. Zygentoma 12

3
6
P
aleopter
a
1
. Intro
d
uct
i
o
n
12
7
2
.Ep
h
emeroptera
.
127
3
. Odonata 13
6
v
ii
C
ontents
7
The
P

leco
p
teroid,
B
lattoid
,
an
d
O
rthoptero
id
O
rder
s
1
.
Introduction
147
2. P
l
eco
p
ter
a
.
147
3. Em
bi
opter
a

.
1
53
4
.D
i
ct
y
opter
a
1
5
6
5
. Iso
p
tera
.
1
6
3
6. Gr
y
lloblattodea
1
7
3
7. Derma
p
ter

a
17
5
8
.P
h
asm
ida
17
9
9. Mantop
h
asmato
d
e
a
.
182
10. Orthoptera
184
11
. Zora
p
tera
.
19
5
8
T
h

e
H
em
i
ptero
id
O
rder
s
1. Intro
d
uct
i
on
.
1
99
2. Psocoptera 1
99
3. Phthiraptera
.

203
4
. Hemi
p
ter
a
.

210
5
. Thysanopter
a

233
9
The
Panor
p
o
id
Order
s
1
.
Intro
d
uct
i
on
.

239
2
. Meco
p
ter
a

239
3. Di
p
tera
.

243
4
.S
iph
ona
p
ter
a
2
64
5
. Trichopter
a
.
2
68
6
. Lepidopter
a
.
27
6
10
T

h
e
R
ema
i
n
i
n
g
E
n
d
optery
g
ote
O
rder
s
1. Intro
d
uct
i
on
.
2
97
2. Mega
l
optera 2
97

3. Rap
hidi
optera
.

299
4
. Neuro
p
tera
301
5
. Coleo
p
tera
305
6. Stre
p
si
p
ter
a

3
2
6
7. Hymenopter
a

330

I
I. Anatomy and Phys
i
olo
g
y
11
T
h
e
I
nte
g
ument
1. Intro
d
uct
i
on
.

355
2. Structure 3
55
3. Cuticle Formation 3
60
3
.1. Preecd
y
sis

360
3
.2. Ec
d
ys
i
s
.

363
3
.3. Postec
d
ys
is

363
viii
C
ontents
3
.4. Coordination of Event
s
.
36
5
4. Functions of the Inte
g
umen
t

3
66
4.1. Stren
g
th and Hardness
366
4.2. Permea
bili
t
y
.

36
7
4.
3
.
C
o
l
o
r
.
3
69
4.4. Other Functions
.

3
7

0
5. Summar
y

3
7
0
6
. Literatur
e

3
7
1
12
S
ensory
S
ystems
1
. Intro
d
uct
i
o
n

3
7
3

2
. Mec
h
anorecept
i
o
n
.
37
4
2.1. Sensor
y
Hair
s

3
7
4
2.2. Pro
p
rioce
p
tors
3
7
5
2.3. S
i
gna
l

Detect
i
on
.

3
7
8
3
. Soun
d
Recept
i
on 37
9
3
.1. Jo
h
nston’s Organ
.
380
3
.2. T
y
mpanal Or
g
ans
.

380

3
.3. Sub
g
enual Or
g
ans
.
.

383
4
.C
h
emorece
p
t
i
on
384
4.1. Locat
i
on an
dS
tructure o
fS
ens
ill
a
384
4.2. P

h
ys
i
o
l
ogy o
f
C
h
emorecept
i
o
n
38
6
5
. Humidit
y
Perceptio
n
.

38
7
6
.Tem
p
erature Perce
p
tion .

.
.

388
7
. Photorece
p
tio
n
.

389
7
.1. Compoun
d
Eye
s
38
9
7.1.1. Form an
d
Movement Percept
i
on
.
3
9
2
7.1.2. Distance Perceptio
n

3
95
7.1.3. Spectral Sensitivit
y
and Color Vision 39
6
7.1.4. Sensitivity to Polarized Ligh
t

39
7
7
.2. S
i
mp
l
e Eye
s
3
98
8. Summary 4
00
9
.L
i
teratur
e

401
1

3
N
ervous an
d
Chemica
l
I
nte
g
ration
1.
Introductio
n
4
05
2
. Nervous Syste
m
.
4
05
2.1. Centra
l
Nervous System
.
4
08
2.2. V
i
scera

l
Nervous S
y
ste
m

411
2.3. Ph
y
siolo
gy
of Neural Inte
g
ratio
n
411
2.4. Learnin
g
and Memor
y
41
5
3
.En
d
ocr
i
ne System 417
3
.1. Neurosecretory Ce

ll
san
d
Corpora Car
di
ac
a
.
41
7
3
.2. Corpora A
ll
at
a
.
41
9
3
.3. Molt Gland
s

420
3
.4.
O
ther Endocrine
S
tructures
.

420
4. Insect
S
em
i
oc
h
em
i
ca
l
s 421
4.1. P
h
eromone
s
422
ix
C
ontents
4.1.1. Sex Pheromones
422
4.1.2. Caste-Re
g
ulatin
g
Pheromones 425
4.1.3. A
gg

re
g
ation Pheromone
s
42
5
4.1.4. A
l
arm P
h
eromones
.
42
6
4.1.
5
. Trail-Marking Pheromone
s
427
4.1.
6
. Spacin
g
(Epideictic) Pheromone
s

428
4.
2
.

Kairomones
.

429
4
.
3
. Allomones
429
5
. Environmental, Neural, and Endocrine Interaction 43
0
6
. Summar
y
.
4
3
1
7
.
L
i
terature
.

432
14
Muscles a
n

d
Loco
m
o
ti
on
1
.
Introduction
.

437
2. Musc
l
es
.
4
3
7
2
.1.
S
tructur
e
4
38
2
.2. P
hy
s

i
o
l
o
gy
44
1
3. Locomotion
443
3
.1. Movement on or Throu
g
h a Substrat
e

443
3
.1.1. Walking 44
3
3
.1.2. Jump
i
ng 44
7
3
.1.3. Craw
li
n
g
an

d
Burrow
i
n
g
.
44
8
3
.2. Movement on or Throu
g
h Wate
r
.

449
3
.2.1. Surface Runnin
g
.
.

449
3
.2.2. Swimming by Means of Legs
.
4
50
3
.2.3. Sw

i
mm
i
ng
b
yOt
h
er Means
.
4
51
3.3. F
li
g
h
t 4
5
2
3
.3.1. Structural Basis
.
4
5
2
3
.3.2. Aerod
y
namic Consideration
s
.

45
3
3
.3.3. Mechanics of Wing Movements 4
58
3
.3.4. Contro
l
o
f
W
i
ng Movement
s
4
60
3
.3.
5
. Flight Metabolis
m
4
6
2
3
.4. Orientation 4
64
4
.
S

ummar
y
46
5
5
. Literatur
e
.
4
66
15
G
a
s
E
xc
h
an
g
e
1. Intro
d
uct
i
on
.
4
69
2. Or
g

an
i
zat
i
on an
d
Structure o
f
t
h
e Trac
h
ea
l
S
y
stem 47
0
2.
1
.
Tracheae and Tracheoles
.

4
7
0
2
.2. S
p

iracles
4
7
3
3. Movement o
f
Gases w
i
t
hi
nt
h
e Trac
h
ea
l
System 474
3
.1. D
iff
us
i
o
n
.
47
5
3
.2. D
i

scont
i
nuous Gas Exc
h
an
ge
.
47
6
3
.3. Active Ventilation
4
7
7
4
. Gas Exchan
g
e in Aquatic Insect
s

4
7
9
4
.1. C
l
ose
d
Trac
h

ea
l
Systems 479
4
.2. Open Trac
h
ea
l
Systems
.
4
81
x
C
ontents
5
. Gas Exchan
g
e in Endoparasitic Insects
.

484
6
. Summar
y
48
5
7.
Literatur
e

4
85
16
F
ood U
p
tak
e
a
n
d
U
t
i
l
i
zat
i
on
1.
Introductio
n

487
2
.Foo
d
Se
l
ect

i
on an
d
Fee
di
n
g
.
4
8
7
3
.T
h
eA
li
mentary System .
.
48
9
3
.1. Salivar
y
Glands
489
3
.
2
. Fore
g

ut
.

491
3
.3. Midgu
t

492
3
.4. H
i
n
d
gut
.
4
9
6
4
. Gut P
h
ys
i
o
l
og
y
4
96

4
.
1
.
G
ut Movement
s
4
96
4.2. Di
g
estio
n

498
4
.2.1. Digestive Enzymes
.

498
4
.2.2. Factors A
ff
ect
i
ng Enzyme Act
i
v
i
ty 4

99
4
.2.3. Contro
l
o
f
Enzyme Synt
h
es
i
san
d
S
ecret
i
o
n
.

5
00
4
.2.4. Di
g
estion b
y
Microor
g
anism
s

.
501
4.3. Absor
p
tio
n

50
2
5
. Metabolism
503
5
.1.
S
ites of Metabolism.
.
.

503
5
.1.1. Fat Bod
y
.

5
0
4
5
.1.2. M

y
cetoc
y
tes
.
504
5
.2. Carboh
y
drate Metabolis
m

505
5
.3. Li
p
id Metabolism
.

506
5
.4. Amino Acid and Protein Metabolism
.

506
5
.
5
. Metabolism of Insecticides
.

5
0
7
6
. Summar
y
509
7.
Literatur
e

5
1
0
17
The
Circulator
y
S
ystem
1.
Introductio
n

5
1
5
2
.

S
tructur
e
.

5
1
5
3
.P
h
ys
i
o
l
og
y
.

5
1
9
3
.1. C
i
rcu
l
at
i
o

n

5
1
9
3
.2. Heartbea
t
520
4
. Hemol
y
mph
5
2
1
4.1. P
l
asm
a

5
2
2
4
.1.1. Compos
i
t
i
on

5
22
4.
1
.
2
.
Funct
i
on
s
.

5
24
4
.
2
. Hemoc
y
te
s
52
4
4
.2.1. Ori
g
in, Number, and Form
5
2

4
4
.2.2. Funct
i
on
s
.

5
2
6
5
. Resistance to Disease
.

530
5
.1. Wound Healin
g
.

5
3
0
5
.2. Immunit
y
.
530
5

.2.1. Resistance to Host Immunit
y

532
xi
C
ontents
6
. Summar
y

5
33
7
.
Literature
.
534
1
8
Ni
trogenou
s
E
x
c
r
e
ti
o

n
a
n
d
S
alt an
d
W
ater
B
a
l
ance
1
.
Introduction
.
53
7
2
. Excretor
ySy
stems
537
2
.1. Ma
l
p
i
g

hi
an Tu
b
u
l
es—Rectum
537
2
.2. Ot
h
er Excretory Structures
.

5
3
9
3. N
i
tro
g
enous Excret
i
on
.

5
41
3
.1. The Nature of Nitro
g

enous Wastes 54
1
3
.2. Ph
y
siolo
gy
of Nitro
g
enous Excretio
n
.

5
4
3
3
.3. Storage Excret
i
on
.

5
4
5
4
.
S
a
l

tan
d
Water Ba
l
anc
e

5
4
6
4
.1. Terrestr
i
a
l
Insects
.

5
4
6
4
.2. Freshwater Insect
s
550
4
.
3
. Brackish-Water and
S

alt
w
ater Insect
s

551
5
. Hormonal
C
ontrol
.

554
6
. Summar
y

556
7. L
i
teratur
e
.

55
6
I
II. Re
p
roduction and Develo

p
ment
19
R
e
p
roductio
n
1
.
Introduction
.

561
2. Structure and Function of the Reproductive System
5
61
2
.1. Fema
l
e
53
2
2.
2
.
Male
.

5

6
5
3. Sexual Maturation 568
3
.1. Female
568
3
.1.1. V
i
te
ll
ogenes
i
s 56
9
3
.1.2. V
i
te
lli
ne Mem
b
rane an
dCh
or
i
on
F
ormat
i

on
.

5
70
3
.1.3. Factors Affectin
g
Sexual Maturit
y
in th
e
Fe
m
a
l
e
.

5
72
3
.2. Ma
le
.
579
4
. Mat
i
ng Be

h
av
i
o
r
.

581
4
.1. Mate Locat
i
on an
d
Reco
g
n
i
t
i
on
5
8
1
4
.2. Courtship 58
2
4
.3. Co
p
ulation 583

4.
3
.1. Insemination
58
4
4
.4. Postcopu
l
atory Be
h
av
i
or
.
.

586
5
. Ovulatio
n
.

5
8
7
6. Sperm Use, Entr
y
into the E
gg
, and Fertilization

5
87
6
.1. S
p
erm Us
e
.
587
6
.2. Sperm Entry into the Egg
s

588
6
.
3
. Fertilizatio
n

588
xii
C
ontents
7
. Ovipositio
n
.

5

8
9
7
.1. Site Selection 58
9
7
.2. Mechanics and Control of Ovi
p
osition 590
7
.
3
.
O
ot
h
eca
e
.

590
8
. Summary
59
1
9
. Literatur
e

59

3
2
0
Embr
y
oni
c
Develo
p
men
t
1.
Introductio
n
59
7
2
.C
l
eavage an
d
B
l
asto
d
erm Format
i
o
n
.

597
3
. Format
i
on an
dG
ro
w
t
h
o
fG
erm Ban
d

59
8
4
. Gastrulation, Somite Formation, and Se
g
mentation
6
0
2
5. Formation of Extra-Embr
y
onic Membranes 605
6
. Dorsal Closure and Katatre
p

sis
606
7
. Tissue and Organ Developmen
t
.

607
7
.1. Appen
d
ages
60
7
7
.2. Inte
g
ument an
d
Ecto
d
erma
l
Der
i
vat
i
ves
.
.

6
0
8
7
.3. Central Nervous S
y
stem
.

6
09
7
.4. Gut and Derivatives .
.
.
61
1
7
.5. Circulatory System, Muscle, and Fat Body.
.

6
1
1
7
.6. Reproductive System
.

6

1
2
8
. Spec
i
a
l
Forms o
f
Em
b
ryon
i
cDeve
l
opment
.

6
12
8
.1. Partheno
g
enesi
s
.

6
1
3

8
.2. Pol
y
embr
y
on
y
.
61
4
8
.3. Viviparity
.

6
1
4
8
.4. Pae
d
ogenes
i
s
6
17
9
. Factors A
ff
ect
i

ng Em
b
ryon
i
cDeve
l
opmen
t
.

6
1
7
1
0. Hatchin
g
.

6
1
9
11
.
S
ummar
y
619
1
2
.

Literatur
e

6
21
21
P
ostembryoni
c
D
eve
l
opmen
t
1
. Intro
d
uct
i
o
n

6
2
3
2
. Growt
h
.

6
2
4
2.1. Ph
y
sical Aspect
s

6
2
4
2.2. Biochemical Chan
g
es durin
g
Growt
h

6
2
6
3
. Forms o
f
Deve
l
o
p
ment
6

2
7
3
.1. Ameta
b
o
l
ous Deve
l
opmen
t

6
2
8
3
.2. Hem
i
meta
b
o
l
ous Deve
l
opment
6
28
3
.3. Holometabolous Develo
p

ment
.

6
28
3.3.1. The Larval Sta
g
e
630
3.3.2. Heteromor
ph
os
i
s
631
3.3.3. T
h
e Pupa
l
Stag
e
.

63
1
4. H
i
sto
l
o

gi
ca
l
C
h
an
g
es Dur
i
n
g
Metamorp
h
os
i
s
6
3
4
4.1. Exopter
yg
ote Metamorphosi
s

6
3
4
4.2. Endopter
yg
ote Metamorphosi

s

634
5
. Eclosio
n
.
639
6
. Control of Development.
.

6
3
9
xiii
C
ontents
6
.1. Endocrine Re
g
ulation of Development
6
40
6
.2. Factors Initiatin
g
and Terminatin
g
Molt C

y
cles
.

6
4
3
7. Po
l
ymorp
hi
s
m

6
4
5
8. Summar
y

6
4
9
9
. Literature
.
6
50
IV
.

E
co
l
og
y
22
T
h
e
A
b
i
o
ti
c
E
n
v
ir
o
nm
e
nt
1
.
Introduction
.

655
2. Tem

p
erature
655
2
.1. E
ff
ect on Deve
l
opment Rat
e
.

655
2
.2. E
ff
ect on Act
i
v
i
t
y
an
d
D
i
spersa
l
.
6

5
7
2
.3. Temperature-S
y
nchronized Development an
d
E
mer
g
enc
e
.

658
2
.4. Surv
i
va
l
at Extreme Tem
p
eratures
.
65
9
2.4.1.
C
o
ld

-Har
di
ness.
.
.
6
59
3. L
igh
t
.

662
3
.1. Dail
y
Influences of Photoperiod
66
2
3
.1.1. Circadian Rh
y
thm
s

663
3
.2. Seasona
l
In

fl
uences o
f
P
h
oto
p
er
i
o
d
.

666
3
.2.1. Nature an
d
Rate o
f
Deve
l
opment
667
3
.2.2. Repro
d
uct
i
ve A
bili

t
y
an
d
Capac
i
t
y
.

668
3
.2.3. Dia
p
ause
668
4. W
ater


6
74
4
.1. Terrestr
i
a
l
Insects
.

6
74
4
.2. Aquat
i
c Insects
.

6
7
7
5
. Weathe
r

6
78
5.1. Weather and Insect Abundanc
e

6
7
8
5.2. Mi
g
ration
.
67
9
5

.2.1. Categories of Migratio
n
.

681
6. Summar
y

686
7. L
i
teratur
e
.

6
88
23
T
he Biotic
E
nv
i
ronment
1. Intro
d
uct
i
on
.

6
91
2. Foo
d
an
d
Trop
hi
cRe
l
at
i
ons
hi
ps
691
2
.1. Quantitative Aspects
.
.

6
91
2
.2. Qualitative As
p
ects 694
3
. Insect-Plant Interactions 694
3

.1. Her
biv
ores
.
6
94
3
.2. Insect-P
l
ant Mutua
li
sm.
.

697
3
.3. Detritivores
.
7
01
4
. Interactions between Insects and Other Animals 70
2
4
.1. Intras
p
ecific Interactions
.
.
7

02
4.1.1. Un
d
erpopu
l
at
i
on 7
02
4.1.2. Overpopu
l
at
i
on 70
3
x
i
v
C
ontents
4.2. Interspecific Interactions
.
70
5
4
.2.1. Com
p
etition and Coexistence 705
4
.2.2. Predator-Pre

y
Relationships
.
7
09
4
.2.
3
. Insect-Insect Mutua
li
sm
s
71
1
5
. Insect Disease
s
.
711
5
.1. Epizootics

712
5
.2. T
y
pes of Patho
g
ens
.

7
13
5
.2.1. Bacteri
a
.
7
13
5
.2.2. Rickettsias
.
71
5
5
.2.
3
. Viruses
.
71
5
5
.2.4. Fun
gi
.
71
6
5
.2.5. Protozoa

7

1
7
5
.2.
6
. Nematodes .
.
7
18
6
. Summary 71
8
7
.L
i
teratur
e
72
0
24
In
sec
t
sa
n
d
H
umans
1
. Intro

d
uct
i
o
n
72
5
2
. Bene
fi
c
i
a
l
Insect
s
.
72
6
2.1. Insects W
h
ose Pro
d
ucts Are Commerc
i
a
lly
V
aluabl
e

7
2
7
2
.
2
.
Insects as Pollinators
.
7
28
2.3. Insects as Agents o
f
B
i
o
l
og
i
ca
l
Contro
l

.
72
8
2.4. Insects as Human Foo
d

7
3
1
2.
5
. Soil-Dwellin
g
and Scaven
g
in
g
Insect
s
.
73
3
2.
6
. Other Benefits of Insect
s
73
5
3
. Pest Insect
s
.
7
36
3
.1. Insects That Affect Humans Directly

.
7
36
3
.2. Pests o
f
Domest
i
cate
d
An
i
ma
l
s
.
74
0
3
.3. Pests o
f
Cu
l
t
i
vate
d
P
l
ant

s
740
3
.4. Insect Pests of Stored Product
s
7
43
4
. Pest Contro
l
.
7
43
4.1. Legal Control
.
74
6
4.2.
Ch
em
i
ca
lC
ontro
l

.
74
6
4.3. B

i
o
l
og
i
ca
l
Contro
l

.
7
5
3
4
.3.1. Microbial Contro
l
7
57
4.4. Genetic Control
.
7
66
4.
5
.
C
ultural
C
ontro

l
.
76
9
4.6. Integrated Pest Managemen
t
.
77
0
5
. Summary 77
5
6
. Literatur
e
77
6
I
n
de
x
.
7
83
P
re
f
ac
e
T

he stron
g
l
y
favorable reception accorded previous versions of this book, to
g
ether with the
not infrequent ur
g
in
g
s of collea
g
ues and students, encoura
g
ed me to take on the task o
f
preparing a third edition of
E
ntomology. My early retirement, in 1999, freed up the time
necessary
f
or a pro
j
ect o
f
t
hi
ss
i

ze, an
df
or t
h
e past 2 years my e
ff
ort
h
as
b
een a
l
most ent
i
re
l
y
f
ocuse
di
nt
hi
s
di
rect
i
on. O
b
v
i

ous
l
y, a
ll
c
h
apters
h
ave
b
een up
d
ate
d
;t
hi
s
i
nc
l
u
d
es not on
l
y
t
he addition of new information and concepts (some of which are hi
g
hli
g

hted below), bu
t
also the reduction or exclusion of material no lon
g
er considered ‘mainstream’ so as to keep
t
he book at a reasonable size
.
My strong
b
e
li
e
f
t
h
at an
i
ntro
d
uctory entomo
l
ogy course s
h
ou
ld
present a
b
a
l

ance
d
t
reatment o
f
t
h
esu
bj
ect st
ill h
o
ld
san
di
sre
fl
ecte
di
nt
h
e retent
i
on o
f
t
h
e
f
ormat o

f
ear
li
er
editions, namel
y
, arran
g
ement of the book into four sections: Evolution and Diversit
y
,
Anatom
y
and Ph
y
siolo
gy
, Reproduction and Development, and Ecolo
gy.
S
ection I (Evolution and Diversity) has again undergone a great reworking, mainl
y
b
ecause t
h
e
l
ast
d
eca

d
e
h
as seen t
h
e uncover
i
ng o
f
s
i
gn
ifi
cant new
f
oss
il
ev
id
ence, an
d
th
e app
li
cat
i
on o
f
mo
l

ecu
l
ar an
d
c
l
a
di
st
i
c ana
l
yses to extant groups. As a resu
l
t,
id
ea
s
b
oth on the relationships of insects to other arthropods and on the hi
g
her classification of
man
y
orders have chan
g
ed drasticall
y
. However, as in previous editions, I have stresse
d

t
hat most ph
y
lo
g
enies are not ‘embedded in stone’ but represent the consensus based o
n
ex
i
st
i
ng
i
n
f
ormat
i
on; t
h
us, t
h
ey are
li
a
bl
etore
fi
nement as a
ddi
t

i
ona
ld
ata are
f
ort
h
com
i
ng.
C
h
apter 1
di
scusses t
h
eevo
l
ut
i
on o
f
Insecta
i
nre
l
at
i
on to ot
h

er art
h
ropo
d
s, emp
h
as
i
z
i
ng
th
ea
g
e
l
ess
d
e
b
ate on w
h
et
h
er art
h
ropo
d
s
f

orm a monop
hyl
et
i
corpo
ly
p
hyl
et
i
c
g
roup
,
and the relationship of insects to other hexapodous arthropods. Evolutionar
y
relationship
s
w
ithin the Insecta are considered in Chapter 2, to
g
ether with discussion of the factors that
contr
ib
ute
d
to t
h
e overw
h

e
l
m
i
ng success o
f
t
h
e group. C
h
apter 3 serves two purposes:
I
t prov
id
es a
d
escr
i
pt
i
on o
f
externa
l
structure, w
hi
c
h
rema
i

ns t
h
epr
i
nc
i
pa
lb
as
i
sonw
hi
c
h
i
nsects can
b
ec
l
ass
ifi
e
d
an
did
ent
ifi
e
d
,w

hil
e stress
i
n
gdi
vers
i
t
y
w
i
t
h
re
f
erence to mout
h
part
and appenda
g
e modifications. In Chapter 4 the principles of classification and identification
are outlined, and a ke
y
to the orders of insects is provided. Diversit
y
of form and habits is
again emphasized in Chapters
5
to 10, which deal with the orders of insects, including th
e

M
antop
h
asmato
d
ea, esta
bli
s
h
e
d
on
l
y
i
n 2002. For many or
d
ers, new propose
d
p
h
y
l
ogen
i
e
s
are presente
d
,an

d
t
h
etext
h
as un
d
er
g
one s
ig
n
ifi
cant rearran
g
ement to re
fl
ect mo
d
ern
id
eas
on the classification of these taxa
.
x
v
xv
i
Pre
f

ac
e
T
he chapters in Section II (Anatom
y
and Ph
y
siolo
gy
) deal with the homeostatic s
y
stem
s
o
f insects; that is, those s
y
stems that keep insects ‘in tune’ with their environment, enablin
g
them to develop and reproduce optimall
y
. The section be
g
ins with a discussion of the in-
tegument (C
h
apter 11), as t
hi
s
h
as

h
a
d
suc
h
a pro
f
oun
di
n
fl
uence on t
h
e success o
fi
nsects.
C
h
apter 12 exam
i
nes sensory systems, w
h
ose
f
orm an
df
unct
i
on are great
l

y
i
n
fl
uence
db
y
t
h
e cut
i
cu
l
ar nature o
f
t
h
e
i
nte
g
ument. In C
h
apter 13, w
h
ere neura
l
an
d
c

h
em
i
ca
li
nte
g
rat
i
on
are discussed, new sections on kairomones and allomones have been included. Cha
p
ter 1
4
c
onsiders muscle structure and function, includin
g
locomotion. In this chapter the section
o
n
fli
g
h
t
h
as
b
een s
i
gn

ifi
cant
l
yrev
i
se
d
, espec
i
a
ll
yw
i
t
h
respect to recent proposa
l
s
f
or t
h
e
generation of lift using non-steady-state aerodynamics. Chapter 1
5
reveals the remarkable
e
fficiency of the tracheal system in gaseous exchange, and Chapter 1
6
deals with the ac
-

q
uisition and utilization of food. Chapter 17 describes the structure and functions of the
c
irculator
y
s
y
stem, includin
g
the immune response of insects about which much has bee
n
l
earned in the
p
ast decade. New to this cha
p
ter is a section on how
p
arasites and
p
arasitoids
are a
bl
eto
d
e
f
en
d
t

h
emse
l
ves aga
i
nst t
h
e
h
ost
i
nsect’s
i
mmune system. C
h
apter 18 conc
l
u
d
e
s
t
hi
s sect
i
on w
i
t
h
a

di
scuss
i
on o
f
n
i
trogenous waste remova
l
an
d
sa
l
t/water
b
a
l
ance
.
In Section III reproduction (Chapter 19), embr
y
onic development (Chapter 20), and
postembr
y
onic development (Chapter 21) are discussed. Chapter 19 includes additiona
l
i
nformation on behavioral aspects of reproduction (courtship, mate guarding and sexual
se
l

ect
i
on), as we
ll
as sperm prece
d
ence. C
h
apter 21
h
as
b
een rev
i
se
d
to prov
id
eanup
d
ate
d
account o
f
t
h
een
d
ocr
i

ne regu
l
at
i
on o
fd
eve
l
opment an
d
mo
l
t
i
ng.
Section IV (Ecolo
gy
) examines those factors that affect the distribution and abundance
o
f insects. In Chapter 22 abiotic (ph
y
sical) factors in an insect’s environment are considered
.
Cha
p
ter 23 deals with the biotic factors that influence insect
p
o
p
ulations and serves as a

b
as
i
s
f
or t
h
e
fi
na
l
c
h
a
p
ter,
i
nw
hi
c
h
t
h
es
p
ec
ifi
c
i
nteract

i
ons o
fi
nsects an
dh
umans are
di
scusse
d
.O
f
a
ll
o
f
t
h
ec
h
apters, C
h
apter 24
h
as rece
i
ve
d
t
h
e most

d
rast
i
c over
h
au
l
; suc
h
h
as
b
een t
h
e ‘pro
g
ress’ (an
d
t
h
e costs o
f
suc
h
pro
g
ress)
i
nt
h

e
b
att
l
ea
g
a
i
nst
i
nsect pests
.
As ma
y
be inferred from the openin
g
para
g
raph of this Preface, the book is intended as a
text for seniorunder
g
raduates takin
g
their first course in entomolo
gy
. Such students probabl
y
will h
aveane
l

ementary
k
now
l
e
d
ge o
fi
nsects acqu
i
re
df
rom an ear
li
er course
i
n genera
l
zoo
l
ogy,aswe
ll
as a
b
as
i
cun
d
erstan
di

ng o
f
an
i
ma
l
p
h
ys
i
o
l
ogy an
d
eco
l
og
i
ca
l
pr
i
nc
i
p
l
es
.
W
i

t
h
suc
h
a
b
ac
k
groun
d
, stu
d
ents s
h
ou
ld h
ave no
diffi
cu
l
ty un
d
erstan
di
ng t
h
e text.
P
reparation of the third edition has benefited, not onl
y

from both published and un
-
solicited reviews of previous editions, but also from m
y
solicitation of comments on the
c
ontent of specific chapters from experts in those areas. Of course, any errors that remain,
an
d
I
h
ope t
h
ese are extreme
l
y
f
ew, are my respons
ibili
ty. I
h
ave en
j
oye
d
prepar
i
ng t
hi
s

t
hi
r
d
e
di
t
i
on,
f
or
i
t
h
as g
i
ven me, once aga
i
n, t
h
e opportun
i
ty to
d
e
l
ve
i
nto aspects o
f

ento
-
m
olo
gy
that are well outside the ran
g
e of an ‘insect sexolo
g
ist’. For example, I never ceas
e
to be impressed b
y
the remarkable discoveries and insi
g
hts of those entomolo
g
ists who deal
w
ith fossil insects, by those who develop integrated strategies for the management of insect
pest popu
l
at
i
ons, an
db
yt
h
e pat
i

ence an
dd
e
di
cat
i
on (
a
n
d
i
mag
i
nat
i
on—see C
h
apter 4
,
S
ect
i
on 2) o
fi
nsect taxonom
i
sts. Hope
f
u
ll

y, rea
d
ers o
f
t
h
enewe
di
t
i
on w
ill
rece
i
ve t
h
e
same en
j
o
y
ment
.
C
edric
G
illot
t
Pr
ofesso

rEm
e
r
itus
U
niversity o
f
Sas
k
atc
h
ewan
,
Sas
k
atoon, Sas
k
atc
h
ewan, Cana
d
a
A
cknowled
g
ments
T
hou
g
h the book has sin

g
le authorship, its preparation would not have been possible bu
t
for m
y
collea
g
ues, too numerous to mention individuall
y
, who provided information an
d
answered specific questions that improved the book’s content and currency. To these people
I
a
m
m
ost grate
f
u
l.
Mr. Denn
i
s Dyc
k
an
d
Mrs. S
hi
r
l

ey Bro
d
s
k
y are t
h
an
k
e
df
or t
h
e
i
r cons
id
era
bl
e ass
i
stance
w
ith preparation of the ori
g
inal fi
g
ures. For this edition, all fi
g
ures were converted int
o

electronic format and, when necessar
y
, reworked b
y
Mr. D
y
ck to achieve
g
reater uniformit
y
of style
.
T
h
an
k
s are a
l
so exten
d
e
d
to a
l
arge num
b
er o
f
pu
bli

s
h
ers, e
di
tors, an
d
pr
i
vate
i
n
di
v
id
ua
ls
wh
oa
ll
owe
d
me to use mater
i
a
l
s
f
or w
hi
c

h
t
h
ey
h
o
ld
copyr
i
g
h
t. T
h
e source o
f
eac
hfi
gure
is acknowled
g
ed individuall
y
in the text.
Iam
g
rateful to the Universit
y
of Saskatchewan, which
g
ranted me the facilities neces-

sary to bring this project to fruition. I specifically acknowledge the assistance given by staff
i
nt
h
eL
ib
rary’s
i
nter-
lib
rary
l
oans
d
epartment; so numerous were my requests
f
or mater
i
a
l
th
at I
f
e
l
t, at t
i
mes, as t
h
oug

h
t
h
ey were my persona
l
ass
i
stants! T
h
e con
fid
ence, pat
i
ence
,
and assistance of Kluwer Academic Publishers, especiall
y
Zuzana Bernhart (Publishin
g
E
ditor, Life Sciences), Ineke Ravesloot (Assistant to the Publishin
g
Editor), and Tonn
y
van
E
ekelen (Production Su
p
ervisor, Books) are also a
pp

reciated.
F
i
na
ll
y, t
h
e enormous
h
e
l
pg
i
ven me
b
ymyw
if
e, Anne,
i
sac
k
now
l
e
d
ge
d
.To
h
er

f
e
ll
t
h
e
ma
j
or tas
k
o
f
proo
f
rea
di
ng to ensure t
h
at t
h
erev
i
se
d
text was co
h
erent,
fi
gures were correct
l

y
num
b
ere
d
,
l
a
b
e
l
e
d
an
d
c
i
te
d
,re
f
erence
li
sts were accurate, an
d
ta
bl
es were comp
l
ete. S

h
e
also checked cop
y
ri
g
ht approvals and assisted in preparation of the index. It is to her that
t
his book is dedicated
.
xvii
I
E
volution and Diversit
y
1
A
rthropod Evolution
1
. Intr
oduc
t
ion
Despite their remarkable diversit
y
of form and habits, insects possess several commo
n
features b
y
which the

g
roup as a whole can be distin
g
uished. The
y
are
g
enerall
y
small
arthropods whose bodies are divisible into cephalic, thoracic, and abdominal re
g
ions. The
h
ea
d
carr
i
es one
p
a
i
ro
f
antennae, one
p
a
i
ro
f

man
dibl
es, an
d
two
p
a
i
rs o
f
max
ill
ae (t
h
e
hi
n
d
pa
i
r
f
use
d
to
f
orm t
h
e
l

a
bi
um). Eac
h
o
f
t
h
ree t
h
orac
i
c segments
b
ears a pa
i
ro
fl
egs
an
d
,
i
nt
h
ea
d
u
l
t, t

h
e meso- an
d
/or metat
h
orac
i
cse
g
ments usua
lly h
aveapa
i
ro
f
w
i
n
g
s.
Abdominal appenda
g
es, when present,
g
enerall
y
do not have a locomotor
y
function. The
g

enital aperture is located posteriorl
y
on the abdomen. With few exceptions e
gg
s are laid
,
an
d
t
h
e young
f
orm may
b
equ
i
te
diff
erent
f
rom t
h
ea
d
u
l
t; most
i
nsects un
d

ergo some
d
egre
e
o
f
metamorp
h
os
i
s
.
A
l
t
h
ou
gh
t
h
ese ma
y
seem
i
n
i
t
i
a
lly

to
b
ean
i
nausp
i
c
i
ous set o
f
c
h
aracters, w
h
en t
h
e
y
are examined in relation to the environment it can be seen quite readil
y
wh
y
the Insect
a
h
ave become the most successful
g
roup of livin
g
or

g
anisms. This aspect will be discusse
d
i
nC
h
a
p
ter 2
.
I
nt
h
e present c
h
apter we s
h
a
ll
exam
i
ne t
h
e poss
ibl
eor
i
g
i
ns o

f
t
h
e Insecta, t
h
at
i
s, t
h
e
ev
ol
ut
i
onar
y
re
l
at
i
ons
hi
ps o
f
t
hi
s
g
roup w
i

t
h
ot
h
er art
h
ropo
d
s. In or
d
er to
d
ot
hi
s mean-
in
g
full
y
it is useful first to review the features of the other
g
roups of arthropods. As wil
l
b
ecome apparent below, the question of arthropod ph
y
lo
g
en
y

is controversial, and variou
s
th
eor
i
es
h
ave
b
een
p
ro
p
ose
d
.
2. Arthropod Diversit
y
Art
h
ropo
d
ss
h
are certa
i
n
f
eatures w
i

t
h
w
hi
c
h
t
h
ey can
b
e
d
e
fi
ne
d
.T
h
ese
f
eatures are
:
se
g
mented bod
y
covered with a chitinous exoskeleton that ma
y
be locall
y

hardened and
is periodicall
y
shed, ta
g
mosis (the
g
roupin
g
of se
g
ments into functional units, for exam
-
ple, head, thorax, and abdomen in insects), presence of preoral segments, paired jointed
appen
d
ages on a var
i
e
d
num
b
er o
f
segments,
h
emocoe
li
c
b

o
d
ycav
i
ty conta
i
n
i
ng ost
i
ate
h
eart enc
l
ose
d
w
i
t
hi
n a per
i
car
di
um, nervous system compr
i
s
i
ng
d

orsa
lb
ra
i
nan
d
ventra
l
g
an
g
lionated nerve cord, muscles almost alwa
y
s striated, and epithelial tissue almost alwa
ys
non-ciliated
.
3
4
CHAPTER
1
T
hou
g
h the “true” arthropods fit readil
y
within this definition, three small
g
roups,
the On

y
chophora, Tardi
g
rada, and Pentastoma, whose members are soft-bodied, wormlike
animals with un
j
ointed appenda
g
es, are less obviousl
y
arthropodan and each is usuall
y
g
i
ven separate p
h
y
l
um status
.
2.1.
O
nychophora, Tard
ig
rada, and Pentastoma
T
he approximatel
y
200 extant species of On
y

chophora (Fi
g
ure 1.lA) are terrestria
l
animals living on land masses derived from the Gondwanan supercontinent: Africa, Cen
-
tra
l
an
d
Sout
h
Amer
i
ca, an
d
Austra
l
as
i
a(Ta
i
t, 2001). T
h
ey are genera
ll
y con
fi
ne
d

to mo
i
st
h
a
bi
tats an
d
are
f
oun
db
eneat
h
stones
i
n rott
i
ng
l
ogs an
dl
ea
f
mo
ld
, etc. T
h
ey possess a com-
bination of annelidan and arthropodan characters and, as a result, are alwa

y
s prominent in
discussions of arthropod evolution. Althou
g
h covered b
y
a thin arthropodlike cuticle (com
-
prising procuticle and epicuticle, but no outer wax layer—see Chapter 11), the body wall is
anne
lid
an, as are t
h
e met
h
o
d
o
fl
ocomot
i
on, un
j
o
i
nte
dl
egs, t
h
e excretory system, an

d
t
h
e
n
ervous system. T
h
e
i
r art
h
ropo
d
an
f
eatures
i
nc
l
u
d
ea
h
emocoe
li
c
b
o
d
ycav

i
ty, t
h
e
d
eve
l
op-
m
ent and structure of the
j
aws, the possession of salivar
yg
lands, an open circulator
y
s
y
stem,
a tracheal respirator
y
s
y
stem, and claws at the tips of the le
g
s. Amon
g
livin
g
arthropods
,

m
yriapods resemble the Onychophora most closely: their body form is similar, tagmosis i
s
restr
i
cte
d
to t
h
et
h
ree-segmente
dh
ea
d
, exsert
il
eves
i
c
l
es are present
i
nD
i
p
l
opo
d
aan

d
Sym-
p
h
y
l
aaswe
ll
as
i
n some onyc
h
op
h
orans, a
di
gest
i
ve g
l
an
di
sa
b
sent, t
h
em
id
gut
i

ss
i
m
il
ar
,
the
g
enital tracts of On
y
chophora resemble those of m
y
riapods, the
g
onopore is subtermi
-
n
al, and certain features of embr
y
onic development are common to both
g
roups (Tie
g
s and
Manton, 1958). However, this resemblance is superficial. Recent on
y
chophorans are but th
e
remnants o
f

a more w
id
esprea
df
auna (
f
oss
il
s
f
rom t
h
e Car
b
on
if
erous are very s
i
m
il
ar t
o
m
o
d
ern
f
orms) t
h
at may

h
ave evo
l
ve
df
rom mar
i
ne
l
o
b
opo
d
s
i
nt
h
e Cam
b
r
i
an per
i
o
d.
Tardigrades are mostly very small (
<
(
(
0

.
5
mm lon
g
) animals, commonl
y
known as water
bears (Fi
g
ure 1.lB). The ma
j
orit
y
of the 800 extant species are found in the temporar
y
water
films that coat mosses and lichens. A few live in
p
ermanent a
q
uatic habitats, either marine
o
r
f
res
h
water, or
i
n water
fil

ms
i
nso
il
an
df
orest
li
tter (K
i
nc
hi
n, 1994; Ne
l
son, 2001)
.
T
h
e
i
r
b
o
d
y
i
s covere
d
w
i

t
h
ac
hi
t
i
n
i
ze
d
cut
i
c
l
ean
db
ears
f
our pa
i
rs o
f
un
j
o
i
nte
dl
egs, eac
h

F
I
GU
RE 1.1
.
(
A
)
P
er
ip
ato
p
s
i
s
s
p. (On
y
chophora); (B
)
P
s
eu
d
echini
s
cu
ss
uillu

s
(
Tardi
g
rada); and (C)
C
e
p
halobaena tetra
p
od
a
(Pentastomida). [A, from A. Sedgewick, 1909,
A
Student’s Textbook o
f
Zoolog
y
,V
ol.
VV
I
II
,
Swan
,
Sonnenhein and Co.
,
Ltd. B
,

C
,
from P P. Grass ´e
,
19
6
8
,
Tr
ait
rr
ede
´
Z
oo
l
ogi
e
,V
ol. 6. By permission of
V
V
Masson et Cie.
]
5
A
RTHR
O
P
O

D
E
V
O
LUTI
O
N
pair bein
g
innervated from a se
g
mental
g
an
g
lion in the ventral nerve cord. The fluid-filled
,
h
emocoelic bod
y
cavit
y
serves as a h
y
drostatic skeleton. The affinities of the tardi
g
rades
remain unclear. The
y
were traditionall

y
ali
g
ned with pseudocoelomates. However, the
y
h
ave a num
b
er o
f
onyc
h
op
h
oran an
d
art
h
ropo
d
an structura
lf
eatures, an
d
t
h
emo
d
ern v
i

e
w
i
st
h
at t
h
ey are c
l
ose
l
yre
l
ate
d
to t
h
ese groups. Recent mo
l
ecu
l
ar ev
id
ence supports t
hi
s
proposa
l
.
Pentastomids (ton

g
ue worms) (Fi
g
ure l.lC), of which about 100 species are known,
are parasitic in the nasal and pulmonar
y
cavities of vertebrates, principall
y
reptiles bu
t
i
nc
l
u
di
ng
bi
r
d
san
d
mamma
l
s. T
h
e
b
o
d
yo

f
t
h
ese worms, w
hi
c
h
range
f
rom2to13cm
l
ong,
i
s covere
d
w
i
t
h
a cut
i
c
l
ean
dh
as two pa
i
rs o
f
anter

i
or un
j
o
i
nte
dl
egs. Interna
ll
y, t
h
ere
i
sa
fl
u
id
-
fill
e
d
cav
i
ty (
d
e
b
ata
bl
ye

i
t
h
er a
h
emocoe
l
or a pseu
d
ocoe
l
om) conta
i
n
i
ngapa
i
re
d
v
e
ntral nerve cord with se
g
mental
g
an
g
lia innervatin
g
each le

g
. Larval development occur
s
in the tissues of an intermediate host, which ma
y
be an omnivorous or herbivorous insect,
fi
sh, or mammal. Though pentastomids are highly modified as a result of their parasitic life,
th
ey are un
d
ou
b
te
dl
y art
h
ropo
d
s. T
h
e
i
r exact pos
i
t
i
on rema
i
ns controvers

i
a
l
,re
l
at
i
ons
hi
ps
wi
t
h
Acar
i
na, myr
i
apo
d
s, an
db
ranc
hi
uran crustaceans
h
av
i
ng
b
een suggeste

d
.
2
.2. Tr
i
l
obi
t
a
The trilobites (Fi
g
ure 1.2), of which almost 4000 species have been described, ar
e
marine fossils that reached their peak diversit
y
in the Cambrian and Ordovician peri-
ods (
5
00–600 million years ago) (Whittington, 1992). Despite their antiquity they were,
h
owever, not pr
i
m
i
t
i
ve
b
ut
hi

g
hl
y spec
i
a
li
ze
d
art
h
ropo
d
s. In contrast to mo
d
ern art
h
ropo
d
s
th
etr
il
o
bi
tes as a w
h
o
l
es
h

ow a remar
k
a
bl
eun
if
orm
i
t
y
o
fb
o
dy
structure. T
h
e
b
o
dy
, usua
lly
F
I
GU
RE 1.2.
T
riarthru
s
eaton

i
(
Trilobita). (A) Dorsal view; and (B) ventral view. [From R. D. Barnes, 1968,
Inverte
b
rate Zoo
l
ogy,2n
d
e
d
. By perm
i
ss
i
on o
f
t
h
e W. B. Saun
d
ers Co., P
hil
a
d
e
l
p
hi
a.]

6
CHAPTER
1
o
val and dorsoventrall
y
flattened, is divided transversel
y
into three ta
g
mata (head, thorax,
and p
yg
idium) and lon
g
itudinall
y
into three lobes (two lateral pleura and a median axis).
The head, which bears a pair of antennae, compound e
y
es, and four pairs of biramous ap-
pen
d
ages,
i
s covere
db
y a carapace. A pa
i
ro

fid
ent
i
ca
lbi
ramous appen
d
ages
i
s
f
oun
d
on
e
ac
h
t
h
orac
i
c segment. T
h
e
b
asa
l
segment o
f
eac

hli
m
bb
ears a sma
ll
,
i
nwar
dl
y pro
j
ect
i
n
g
e
n
di
te t
h
at
i
s use
d
to
di
rect
f
oo
d

towar
d
t
h
e mout
h.
M
uch about the habits of trilobites can be surmised from examination of their remains
and the de
p
osits in which these are found. Most trilobites lived near or on the sea floor.
W
hil
e some spec
i
es preye
d
upon sma
ll
,so
f
t-
b
o
di
e
d
an
i
ma

l
s, t
h
ema
j
or
i
ty were scavengers.
H
owev er,
lik
e eart
h
worms, a
f
ew sma
ll
er tr
il
o
bi
tes too
ki
nmu
d
an
ddi
geste
d
t

h
e organ
ic
m
atter
f
rom
i
t. On t
h
e
b
as
i
so
f
X-ray stu
di
es o
f
pyr
i
t
i
ze
d
tr
il
o
bi

te spec
i
mens, w
hi
c
h
s
h
ow
that trilobites possess a combination of chelicerate and crustacean characteristics, Cisne
(
1974) concluded that the Trilobita, Chelicerata, and Crustacea form a natural
g
roup with a
c
ommon ancestry. Their ancestor would have a body form similar to that of trilobites. Most
aut
h
ors
di
spute t
h
e propose
d
tr
il
o
bi
te-crustacean
li

n
k
,an
d
some even re
j
ect t
h
e assoc
i
at
i
on
b
etween tr
il
o
bi
tes an
d
c
h
e
li
cerates. In
d
ee
d
,t
h

ere are t
h
ose w
h
o suggest t
h
at t
h
etr
il
o
bi
tes
themselves are pol
y
ph
y
letic (Willmer, 1990)
.
Althou
g
h the decline of trilobites (and their replacement b
y
the crustaceans as the
dominant aquatic arthropods) is a matter solely for speculation, Tiegs and Manton (1958)
suggeste
d
t
h
at t

h
e
i
r
b
as
i
c, rat
h
er cum
b
ersome
b
o
d
yp
l
an may
h
ave pro
hibi
te
d
t
h
eevo
l
ut
i
o

n
of f
ast movement at a t
i
me w
h
en
hi
g
hl
y mot
il
e pre
d
ators suc
h
as
fi
s
h
an
d
cep
h
a
l
opo
ds
w
ere becomin

g
common. In addition, the man
y
identical limbs presumabl
y
moved in
a
m
etachronal manner, which is a rather inefficient method in lar
g
eor
g
anisms
.
2.3. The Chelicerate Arthro
p
od
s
Th
enext
f
our groups are o
f
ten p
l
ace
d
toget
h
er un

d
er t
h
e genera
lh
ea
di
ng o
f
C
h
e
li
cerata
because their members possess a bod
y
that is divisible into cephalothorax and abdomen
,
the former usuall
y
bearin
g
a pair of chelicerae (but lackin
g
antennae), a pair of pedipalps,
and four pairs of walkin
g
le
g
s. Althou

g
h there is little doubt of the close relationshi
p
b
etween t
h
eX
i
p
h
osura, Eurypter
id
a, an
d
Arac
h
n
id
a, t
h
e pos
i
t
i
on o
f
t
h
e Pycnogon
id

a
i
s
uncerta
i
n. T
h
oug
h
t
h
ey are usua
ll
y
i
nc
l
u
d
e
d
asac
l
ass o
f
c
h
e
li
cerates, t

h
e
i
ra
ffi
n
i
t
i
es w
i
t
h
o
t
h
er mem
b
ers o
f
t
hi
s
g
roup rema
i
n unc
l
ear, an
d

t
h
ere are some aut
h
ors w
h
o cons
id
er t
h
e
y
deserve more separated status (see Kin
g
, 1973; Manton, 1978; Ed
g
ecombe, 1998; Forte
y
and Thomas, 1998
).
Xi
phosura.
L
imu
l
us po
ly
p
h
emus

,
t
h
e
ki
ng or
h
orses
h
oe cra
b
(F
i
gure 1.3),
i
son
e
of f
our surv
i
v
i
ng spec
i
es o
f
ac
l
ass o
f

art
h
ropo
d
st
h
at
fl
our
i
s
h
e
di
nt
h
eOr
d
ov
i
c
i
an-Upper
D
evonian periods. Kin
g
crabs occur in shallow water alon
g
the eastern coasts of North and
Central America. Three s

p
ecies o
f
Tac
h
ypleu
s
a
n
d
C
arcinoscor
p
ius
o
ccur alon
g
the coast
s
o
f China, Japan, and the East Indies. Like trilobites the
y
are bottom feeders, stirrin
g
up the
su
b
strate an
d
extract

i
ng t
h
e organ
i
c mater
i
a
lf
rom
i
t. I
n
Limu
l
u
s
t
h
ece
ph
a
l
ot
h
orax
i
s covere
d
wi

t
h
a
h
orses
h
oe-s
h
ape
d
carapace. T
h
ea
bd
omen art
i
cu
l
ates
f
ree
l
yw
i
t
h
t
h
e cep
h

a
l
ot
h
orax
an
d
at
i
ts poster
i
or en
d
carr
i
es a
l
on
g
te
l
son. On t
h
e ventra
l
s
id
eo
f
t

h
e cep
h
a
l
ot
h
orax are
six pairs of limbs. The most anterior pair are the chelicerae, and these are followed b
y
fiv
e
pairs of le
g
s. Each le
g
has a lar
g
e
g
nathobase, which serves to break up food and pass it
f
orwar
d
to t
h
e mout
h
.S
i

xpa
i
rs o
f
appen
d
ages are
f
oun
d
on t
h
ea
bd
omen. T
h
e
fi
rst pa
ir
f
use me
di
a
ll
yto
f
orm t
h
e opercu

l
um. T
hi
s protects t
h
e rema
i
n
i
ng pa
i
rs, w
hi
c
hb
ear g
ill
so
n
t
h
e
i
r poster
i
or sur
f
ace.
7
A

RTHR
O
P
O
D
E
V
O
LUTI
O
N
F
IGURE 1.3
.
T
he horseshoe crab
,
L
imulus pol
y
phemus
.
(
A) Dorsal view and (B) ventral view. [From
R
. D. Barnes
,
19
6
8

,
I
nverte
b
rate Zoo
l
ogy
,
2n
d
e
d
.B
y
perm
i
ss
i
on o
f
t
h
e W. B. Saun
d
ers Co., P
hil
a
d
e
l

p
hi
a.]
Eurypter
i
da
.
T
h
e Eurypter
id
a(g
i
ant water scorp
i
ons) (F
i
gure 1.4A) were
f
ormer
ly
i
nc
l
u
d
e
d
w
i

t
h
t
h
eX
i
p
h
osura
i
nt
h
ec
l
ass Merostomata. However, most recent stu
di
es
h
av
e
conc
l
u
d
e
d
t
h
at t
h

e two are not s
i
ster
g
roups an
d
t
h
at t
h
e Merostomata
i
s a parap
hyl
et
ic
assembla
g
e (authors in Ed
g
ecombe, 1998). More than 300 species of this entirel
y
fossil
g
roup of predator
y
arthropods, which existed from the Ordovician to the Permian periods,
are known. Because of their sometimes large size (up to 2.5 m) they are also known a
s
Gi

gantostraca. T
h
ey are
b
e
li
eve
d
to
h
ave
b
een
i
mportant pre
d
ators o
f
ear
l
y
fi
s
h
, prov
idi
n
g
se
l

ect
i
on pressure
f
or t
h
eevo
l
ut
i
on o
fd
erma
lb
one
i
nt
h
e Agnat
h
a. In
b
o
d
yp
l
an t
h
ey wer
e

rather similar to the xiphosurids. Six pairs of limbs occur on the cephalothorax, but, in
contrast to those of kin
g
crabs, the second pair is often
g
reatl
y
enlar
g
ed and chelate formin
g
pedipalps, which presumably served in defense and to capture and tear up prey. The trunk
o
f
eurypter
id
s can
b
e
di
v
id
e
di
nto an anter
i
or prea
bd
omen on w
hi

c
h
appen
d
ages (concea
l
e
d
gill
s) are reta
i
ne
d
an
d
a narrow ta
illik
e posta
bd
omen
f
rom w
hi
c
h
appen
d
a
g
es

h
ave
b
een
l
ost
.
T
hou
g
h the earl
y
eur
y
pterids were marine, adaptive radiation into freshwater and perhap
s
ev
en terrestrial habitats occurred. Indeed, it was from freshwater forms that arachnids are
b
elie
v
ed to ha
v
ee
v
ol
v
ed
.
A

r
ac
hni
da.
Scorp
i
ons, sp
id
ers, t
i
c
k
s, an
d
m
i
tes
b
e
l
ong to t
h
ec
l
ass Arac
h
n
id
aw
h

os
e
approximatel
y6
2,000 species are more easil
y
reco
g
nized than defined. Livin
g
members of
t
he
g
roup are terrestrial (althou
g
h a few mites are secondaril
y
aquatic) and have respirator
y
or
g
ans in the form of lun
g
books or tracheae. In contrast to the two aquatic chelicerate
g
roup
s
d
escr

ib
e
d
ear
li
er, most arac
h
n
id
sta
k
eon
l
y
li
qu
id f
oo
d
, extracte
df
rom t
h
e
i
r prey
b
y means
o
f

ap
h
aryngea
l
suc
ki
ng pump, o
f
ten a
f
ter extraora
ldi
gest
i
on. Scorp
i
ons, o
f
w
hi
c
h
t
h
er
e
are about 1
5
00 livin
g

species, are the oldest arachnids with fossils known from the Silurian.
Some of these fossils were aquatic (Polis, 1990). With about 35,000 species, spiders form
8
CHAPTER
1
F
IGURE 1.4. (A) Eurypterid and (B
)
Ny
mphon rubru
m
(
Pycnogonida). [A, from D. T. Anderson (ed.), 2001
,
I
nverte
b
rate Zoo
l
ogy
,
2nd ed. B
y
permission of Oxford Universit
y
Press. B, from R. D. Barnes. 19
6
8,
I
nverte

b
rate
Z
oolo
gy
, 2nd ed. B
y
permission of the W. B. Saunders Co., Philadelphia.
]
an extremely diverse group. The earliest spider fossils are from the Devonian, and by th
e
Tert
i
ary t
h
esp
id
er
f
auna was very s
i
m
il
ar to t
h
at seen to
d
ay (Foe
li
x, 1997)

.
P
ycno
g
onida
.
T
h
e approx
i
mate
ly
1000 spec
i
es o
fli
v
i
n
g
P
y
cno
g
on
id
a (Pantopo
d
a
)

are the remnants of a
g
roup that ori
g
inated in the Devonian. The
y
are commonl
y
know
n
as sea spiders because of their superficial similarit
y
to these arachnids (Fi
g
ure 1.4B). The
y
are
f
oun
d
at vary
i
ng
d
ept
h
s
i
na
ll

oceans o
f
t
h
ewor
ld
,
b
ut are part
i
cu
l
ar
l
y common
i
nt
h
e
s
h
a
ll
ower waters o
f
t
h
e Arct
i
can

d
Antarct
i
c Oceans. T
h
ey
li
ve on t
h
e sea
fl
oor an
df
ee
d
on
c
oe
l
enterates,
b
r
y
ozoans, an
d
spon
g
es. On t
h
e cep

h
a
l
ot
h
orax
i
sa
l
ar
g
e pro
b
osc
i
s,ara
i
se
d
tubercle bearin
g
four simple e
y
es, a pair of chelicerae and an associated pair of palps, an
d
five pairs of le
g
s. The le
g
s of the first pair differ from the rest in that the

y
are small and
pos
i
t
i
one
d
ventra
ll
y. T
h
ese ov
i
gerous
l
egs are use
di
nt
h
ema
l
e
f
or carry
i
ng t
h
e eggs. T
h

e
a
bd
omen
i
s very sma
ll
an
dl
ac
k
s appen
d
ages.
As note
d
a
b
ove, t
h
e prec
i
se re
l
at
i
ons
hi
ps o
f

t
h
e pycnogon
id
stoot
h
er art
h
ropo
d
s rema
i
n
c
ontroversial. Althou
g
h the presence of chelicerae, the structure of the brain, and the natur
e
o
f the sense or
g
ans are chelicerate characters, the structure and innervation of the proboscis
,
the similarity between the intestinal diverticula and those of annelids, the multiple paire
d
gonopores, an
d
t
h
e suggest

i
on t
h
at t
h
e pycnogon
id
s
h
ave a true coe
l
om s
h
ow t
h
at t
h
ey must
have left the main line of arthropod evolution at a very early date (Sharov, 19
66
). Other
n
on-chelicerate features that the
y
possess are (1) the partial se
g
mentation of the le
g
-bearin
g

part of the bod
y
, (2) the reduction of the opisthosoma to a small abdominal component, and
(
3) the presence, in the male, of ovigerous legs
.
2.4. The Mandibulate Arthro
p
ods
Th
e rema
i
n
i
ng groups o
f
art
h
ropo
d
s (crustaceans, myr
i
apo
d
san
dh
exapo
d
s) were or
i

g-
i
nall
yg
rouped to
g
ether as the Mandibulata b
y
Snod
g
rass (1938) because their members
9
A
RTHR
O
P
O
D
E
VOLUTION
possess a pair of mandibles as the primar
y
masticator
y
or
g
ans. Thou
g
h this view becam
e

w
idel
y
accepted, some later authors, notabl
y
Manton, ar
g
ued forcefull
y
that the mandible of
t
he crustaceans is not homolo
g
ous with that of the m
y
riapods and insects. That is, the term
M
an
dib
u
l
ata s
h
ou
ld
not
b
e use
d
to

i
mp
l
yap
h
y
l
ogenet
i
cre
l
at
i
ons
hi
p
b
ut on
l
y a commo
n
level of advancement reached by several groups independently (Tiegs and Manton, 19
5
8;
M
anton, 1977). T
h
e
d
e

b
ate over w
h
et
h
er t
h
e Man
dib
u
l
ata const
i
tute a monop
hyl
et
i
c
g
rou
p
continues to be vi
g
orous (see chapters in Ed
g
ecombe, 1998; Forte
y
and Thomas, 1998;
also Section 3.3.1), and the conclusion reached t
y

picall
y
hin
g
es on the t
y
pe of evidenc
e
presente
d
.Ev
id
ence
f
rom comparat
i
ve morp
h
o
l
ogy,
bi
oc
h
em
i
stry, an
d
mo
l

ecu
l
ar
bi
o
l
ogy
o
fli
v
i
ng spec
i
es ten
d
s to support monop
h
y
l
y, w
h
ereas
d
ata
f
rom
f
oss
il
s genera

ll
ya
li
g
n
th
e Crustacea w
i
t
h
t
h
eC
h
e
li
cerata. W
i
t
h
t
h
e
i
rtwopa
i
rs o
f
antennae, t
h

e Crustacea wou
ld
appear ver
y
distinct from the other two
g
roups. M
y
riapods and hexapods have a sin
g
le pair
of antennae, a feature that led Sharov (1966) to unite these
g
roups in the Atelocerata. Tie
gs
and Manton (1958) and Manton (1977) went a step further, placing the two groups wit
h
th
eOnyc
h
op
h
ora
i
nt
h
eUn
i
ram
i

a. However,
l
oo
k
s can
b
e
d
ece
i
v
i
ng, an
d
many mo
d
ern
p
h
y
l
ogenet
i
c
i
sts cannot accept t
h
e Ate
l
ocerata (see Sect

i
on 3.3.1) an
d
t
h
eUn
i
ram
i
a (se
e
Sections 3.2.2 and 3.3) as monoph
y
letic taxa
.
C
rustacea
.
T
o
t
he Crustacea belong the crabs, lobsters, shrimps, prawns, barnacles,
an
d
woo
dli
ce. T
h
e Crustacea are a success
f

u
l
group o
f
art
h
ropo
d
s: some 40,000
li
v
i
ng
spec
i
es
h
ave
b
een
d
escr
ib
e
d
an
d
t
h
ere

i
sana
b
un
d
ant
f
oss
il
recor
d
.T
h
e
y
are pr
i
mar
ily
aquatic, and few have mana
g
ed to successfull
y
conquer terrestrial habitats. The
y
exhibit
a remarkable diversit
y
of form; indeed, man
y

of the parasitic forms are unreco
g
nizable i
n
t
he adult stage. Typical Crustacea, however, usually possess the following features: bod
y
di
v
id
e
di
nto cep
h
a
l
ot
h
orax an
d
a
bd
omen; cep
h
a
l
ot
h
orax w
i

t
h
two pa
i
rs o
f
antennae, t
h
re
e
pa
i
rs o
f
mout
h
parts (man
dibl
es an
dfi
rst an
d
secon
d
max
ill
ae), an
d
at
l

east
fi
ve pa
i
rs o
fl
egs;
b
iramous appenda
g
es
.
The reason for the success of Crustacea (and perhaps the reason wh
y
the
y
replace
d
t
rilobites as the dominant aquatic arthropods) is their adaptability. Like their terrestrial
counterparts, t
h
e
i
nsects, crustaceans
h
ave exp
l
o
i

te
d
to t
h
e
f
u
ll
t
h
ea
d
vantages con
f
erre
d
b
y possess
i
on o
f
a segmente
db
o
d
yan
dj
o
i
nte

dli
m
b
s. Pr
i
m
i
t
i
ve crustaceans,
f
or examp
l
e
,
t
he fair
y
shrimp (Fi
g
ure 1.
5
), have a bod
y
that shows little si
g
nofta
g
mosis and limb
specialization. In contrast, in a hi

g
hl
y
or
g
anized crustacean such as the cra
y
fish (Fi
g
ure 1.
6)
t
he appenda
g
es have become specialized so that each performs onl
y
one or two functions,
an
d
t
h
e
b
o
d
y
i
sc
l
ear

l
y
di
v
id
e
di
nto tagmata. In t
h
e
l
arger (
b
ottom-
d
we
lli
ng) Crustacea
spec
i
a
li
ze
dd
e
f
ens
i
ve weapons
h

ave evo
l
ve
d
(e.g., c
h
e
l
ae, t
h
ea
bili
ty to c
h
ange co
l
or
i
n
re
l
at
i
on to t
h
eenv
i
ronment, an
d
t

h
ea
bili
t
y
to move at
high
spee
d
over s
h
ort
di
stances
by
snappin
g
the flexible abdomen under the thorax). B
y
contrast, smaller, planktonic Crustacea
are often transparent and have evolved hi
g
h reproductive capacities and short life c
y
cles to
f
ac
ili
tate sur
viv

a
l
.
My
ria
p
oda
.
T
h
e mem
b
ers o
ff
our groups o
f
man
dib
u
l
ate art
h
ropo
d
s(C
hil
opo
d
a,
Diplopoda, Pauropoda, and S

y
mph
y
la) share the followin
g
features: five- or six-se
g
mente
d
h
ead, unique mandibular bitin
g
mechanism, sin
g
le pair of antennae, absence of compound
F
I
GU
RE 1.5
.
B
r
a
n
c
h
i
n
ecta
s

p., a fairy shrimp
.
[
From R. D. Barnes, 19
6
8, Inverte
b
rate Zoo
l
ogy
,
2n
d
e
d
.B
y
perm
i
ss
i
on o
f
t
h
e W. B. Saun
d
ers Co.,
P
hiladelphia.]

10
CHAPTER
1
FI
GU
RE 1.6. Cra
yfi
s
h
. Ventra
l
v
i
ew o
f
one s
id
etos
h
ow
diff
erent
i
at
i
on o
f
appen
d
a

g
es.
e
y
es, e
l
ongate trun
k
t
h
at
b
ears many pa
i
rs o
fl
egs, art
i
cu
l
at
i
on o
f
t
h
e coxa w
i
t
h

t
h
e sternu
m
(
rat
h
er t
h
an t
h
ep
l
euron as
i
n
h
exapo
d
s), trac
h
ea
l
resp
i
ratory system, Ma
l
p
i
g

hi
an tu
b
u
l
es
f
or excretion, absence of mesenteric ceca, and distinctive mechanism b
y
which the anima
l
e
xits the old cuticle durin
g
ecd
y
sis. Further, the
y
are found in similar habitats (e.
g
., leaf
m
old, loose soil, rottin
g
lo
g
s).
Fo
rt
h

ese reasons, t
h
ey were tra
di
t
i
ona
ll
yp
l
ace
di
nas
i
ng
l
e
l
arge taxon, t
h
e Myr
i
apo
d
a
.
T
h
e monop
h

y
l
et
i
c nature o
f
t
h
e myr
i
apo
d
s
h
as
b
een supporte
db
y some,
b
ut not a
ll
,c
l
a
di
st
ic
ana
ly

ses o
fl
ar
g
e
d
ata sets w
i
t
h
a com
bi
nat
i
on o
f
morp
h
o
l
o
gi
ca
l
an
d
mo
l
ecu
l

ar c
h
aracters
o
f livin
g
species (Wheeler
et al
., 1993; authors in Forte
y
and Thomas, 1998). Yet other
m
orpholo
g
ical and molecular studies indicate that the m
y
riapods constitute a paraph
y
leti
c
o
revenpo
l
yp
h
y
l
et
i
c group. Determ

i
nat
i
on o
f
t
h
ere
l
at
i
ons
hi
ps w
i
t
hi
nt
h
e Myr
i
apo
d
a
h
a
s
prove
d diffi
cu

l
t
b
ecause potent
i
a
ll
y
h
omo
l
ogous c
h
aracters are s
h
are
db
y
diff
erent pa
i
rs o
f
g
roups. For examp
l
e, D
i
p
l

opo
d
aan
d
Pauropo
d
a
h
ave t
h
e same num
b
er o
fh
ea
d
se
g
ments
and one pair of maxillae; Diplopoda and Chilopoda have se
g
mental tracheae; and S
y
mph
y
l
a