Table Of ContentGeneral and Applied Entomology
CONTENTS
PREFACE
I.
InlrocillCliun
.)
IllSclts and R('lalCd :\nima ls
:~.
Extatl;d Anatolll Y or Ilheels
cf.
:nl.ernal :\ nallllll )' ,me! 1'11 ),s iclio).!,y or Insl'CIs
:i.
CrOIl'11t alld :\l elarliorpiJosis or Insect s
6.
I ns{'cl ConI 1'01
7.
I nscCl ic ides
H.
The ( :Iassific;llio)) of IIl Sl~ (, t.~
\ ' 11
(" )
) _
71
7H
~L
Subclass AplLTygota
11 ·1
Orders Tit ysall 11 t;) (Hri,l/iI'llIilcl , .... ;i lvn[i .lh , Fi l'l' I)/'al,l )
and Co llcrnbola (Sprill g/ai/s)
10,
Subclass Pc c r y~()t a
II ~ I
()rde rs Lpll ell1c ro(1lera (,\I((y/lie.I) , ado na la (/)mgort-
fli(·.\' (11Ic/ ])I/1/1.I(,([li('.I) , and I'lc('(lpl t'ra C)'/ IJ /II'/li('.I)
II.
Orclers OnilopLcra (C()c/nollch('.I, G rrI.l.lh lJ!J!){' r.l, (; r ic/{I'IS.
Aa/ydi rls, alld Olh l'T.I ) and Isoptcra ( TI' l"lII i /('.I)
I ~ I
12. Orders Dermaptera (Lan l'ig.I), Embiidina
(l:lIi1Jiiris) ,
Zoraplera (Zo)"{ljJlerons) , COTToclcnli a (p.\()cid.,) alld
Thysan()ptcra (TMi/}s)
l !:i ~~
1:1.
Orders ;\Ialluphaga (C/i ('w iIl J.!, LiCl') and Anoplura
(.Ill/chill ,!!; Liu')
I G·1
1,1
Order Il ell1iplera (T" (' Bugs)
In
1:-,.
Order HOll1opt era (A ldliris, Scal(' !1I.secls, L eafho/J/)('l'S,
all d (JIli N;' )
19H
1 (i.
Orders Co ieoP' tTa (Ha l i f'.\) and Slrcpsi plera (Slyin/lid.n
22K
17.
O rders l\ clIroplcra (J)o /)soll[lil'.\ , Lacewings, A lii Liolls.
and Oill ers) and ~'1 cc() pl era (SCU I pi()1I Fli('J)
2H!-J
v
vi
CONTENTS
18:
9rdcrs Trich<?ptera _(Caddisf/irs) and L epidoptera
" • (M oths, Skii'ilers, and Butterflies)
2DG
19. ", t>rdcr Diptera (Flies) • . . '
:H~2
.
J
' ..
20.
Or~kr Siph op.a pt.e.~~a
. (Fleas)
4 :1:1
~ 1.
Order HyineJ1 ()ptera (Sawflies, Allis. TVa.l/ls. Rf' ('S, (/Ild
Olhe~0
110
22.
Collecting, Mounting, and Prt's('J'vi ng-
lns t'c t~
GI.OSSARY
A SEl.ECTED l)IBl.lO(;RAPJIY
J I'>DEX
T h is textbouk \I"as writt en for st udent s IH'g illllillg';t stlldy of t'nto-
Illolog),. '1 h e' studcnt , his inl crest in ail e! approach t(1 till' slIl>jt'n. ;llld
lhe tyr e of inl orlllJlioll llim t m Irth \\'hilc to 'liIll han : hC{'1l kept
constalltl y ill Illind ill the pr(,parati on of th e text. i\( ost student s tak-
ing th e subj ect ili a), IH' \ 't'!' han ' il1ort' thall tltis O IH' l'Oll rSt', T he Ill ust
illlpOrLant (1ll cStioll
i ~ "\"h;tt suhjeCt matt er slioilid I>e gin'n <I nc!
how sli ould it be jlr t'~(' llt ed j" TII :s It", t is the rt' ~ ult of n]lll'(' th <ln :W
years of t("aching a C() II r.~{' ill g(,lIera l il lle! app lied ('llt()lllology ;JIld
r('pn:'Sl'lIIS til l' ;J IIIII O)"S tll()\lgllt s and \ i(''''s (\ J) til t' ' 1Ihj('('I ,
T Ii !:' a utlior lias strivell HI \\'ril (' sil1lpl y and cl ear ly. and has at-
tl'lllpl cd to present th e subjcct LIS logica ll y :t ~ p()s~ ihll' . Tlt t,
11 101'('
appn)\'Cd pll yl()gTtlC'tic arrallgeml'lll of natural grou ps li as Ilot always
been followed. 1)llt th t,), Inl\'e h cqll ' liLl y been arranged !m' stud y tl l1
tht, more sensil)l(' basis or h:l l>it J t a nd J1lct:l1l1orplwsis.
OIW must always keep in milld that t'nt oll1ology is th t' stlldy of
inscns- lli cir recognitio11 , hiolog-y. ;Incl m lltro!. Ct'lta illl y, til(' sllidy
of t axo!lol11 ), a!lci biolog)' of i IlSt'CI S
i ~ 1I10S1 i 111 porlanl for I he I)(:gin-
ncr. 1\'t'X t ill ilnpOn an{'T arc the app lied pit a~es or tit e scicncc, It is
our IllO llght that morpho logy J Tl(J physiology should be limited LO
on ly a \\'orking' kn(lw ledge in an elelllcllt.ary tcxt.
T lte most effec tive teaching of ecol1omic cJ)t ollw loRY can he done
along "'itll 1;I X()1l011l ic alld iJiologica l stu cl ies, sinc(', at lit is liJ1lt, il is
possib le to tic conlro l to tlte bio logy and the taxonomic group of th e
insect mOle ~a li s l acl<J ril y. ,\I OSI dClai ls (II insect c()l1trol are olllitt ed
bcca ll ~e cOJJtrol mcasures vary so I1IllCh ill d ifferent parts of th e (,O UIl -
try that one IIlU t dt'J end large l
O il local recollll1lendations, Also,
much detailed informa tion pertai ning to d()~ag('s and applica tions of
in ccticicles may he found on the man ufactu rer's label. J'\a t.ura Jl y, 11 (1
textbook will fi t the needs of every instructor. Adeqllate materia l has
been included to allow considerable latitude in the cho ice of subject
matter,
vii
viii
PREFACE
The st.udy of insects IS a most fascinating science, and this book
attempts at every opportunity to arouse interest am o ng- the students.
Altho ugl, many injurious insects have been discussed, it is certai nl y
not the desire 10 crea te the impression that all are harm flll. The
more important beneficial insects are stressed in their proper places.
R alhn' sil1lp le (lnd incomplete keys are given to the more imporlant
grollps, chidl y for th e purpose of aCfJ uainting- the students with their
usc. Certainly, the student in his first course in en tomology will not
prog-ress f(lr in insect taxonom y. A chapter is included on making
insect collectiolls to encollrage students to m ake co llections and CO ll -
tinlle their stllciies. A gleJssary is included to a id with technical terlllS.
i\ textbook in entomo logy of a general nature onl y dips lig'htl y
into the vast amount of the .. ccumul ated knowl edge o f the science. :\
select.ed bihliogra ph y is incillded as an ;,id to uoth teacher and Stll-
dent. A numlJer of the references cont a in exce ll ent hihli ogT(lphies
which will ue o f furth er aiel.
The subject material in this textbook has been taken from many
sOllrces. \Ve (Ire gra tefld to all auth ors and research worker. from
whose works this IHaterial has iJeen d rawn . T he a u thor is indebted
to many pcoplt, for helpful criticisms and suggest iOlls. and for read-
ing the manuscript. 1 especially ",ish to thank H . .J. R ein hard, l'\ . 1\1.
R alJdo lph . J. C. (;a ines. R . _I. Dicke, D. R . King, ~'1. A. Price, D. F.
Mart in , Ada Dunca n, alld .Jo AnlJ 'Moss, T he wriu:r is g-ra tef'ul to
Do n Co llins, C. O. i\()hr, (Inc! j\tfrs . "V . .J. Dobsoll for he lp and sug-
gestions wi t h i If ust ra t ions. 11 fttst.rat ions were loaned ()r perm issioll
was given for use of figures in the literature by a number or ind ivid-
ua ls and companies. Special thanks are dut' F. F. Knipling. L. S. Dil-
lOll , Willialll W . Paul. I)rtKe B. Miller, (;. H . Cillt'. ( ;. F. Ferris,
.J. F. Cooper, P . . J. R eno, H . B. i\Iills, F. O. Essig, Marjorie i\litchell ,
S . .I. Carpenter. P. \\'. Oman. i\ lina i\lax\\"ell, \\I. \ V. Konk le, C. ,\ .
Bieberclorf. Marie Lonning. Gera ld B. Spawn, Hans N ussba um ,
G. F. Know lton. \\I . P . Brad ley. C. F. Garner, F. i\I. Fuller, .Jo hn E.
Simlllons, Florence L. Batson, T. H . Mackintosh , and Blair Coursen .
Collegf' Statioll. T exas
Fclmlfny, 19'7
V. A. LITTLE
CHA PT E R
I
INTRODUCTION
T he place thaI inS(YIS occupy in the world of li\'ing Ihings is impor-
[;)111 as 1ll0S1 all plants and il nimals (Ire affecled in .~() l1l e \fay by Iheir
presence. l\'o other class of animals is so inlimal ely involved in Ille
inlricacies and complexil ies of lhe hiologica l world as arc insecls.
They arc essentiall y lerrcstrial ill habital ; and are dislributl'd frolll
Ihe permafrost line of the Arclic to Ihe icc cap of Ille Antarnic. and
from the mountain tops to tilt> deplhs of ('aVCTllS , Two-thirds or
more of all spec ies 0 1' animals arc inserts, {\nd they arc probahl y ex-
cceded in nU111ber of indi viduals only hy Illicros{,(lpic forms or life.
Insects are an ancient race of anima ls which has persisled fot' Illil-
lions of yC'{\rs, Through the processes (If evolution nature has su-
perb Iy perfected them I hat I hey may SlI rvive under the most ad verse
condili ons and in a divel'sity of environments. Na ture has sllcceeded
in comb ining in thcm certain advantageous characteristics, tlte com-
bination of which is found in no other grollp of animals. An insect
is protected hy a suit of armor (exoskeleton) like knights or o ld.
Associated with th
exoskeleton is remarkable mobility and sma ll-
ness of size. Tn addirion to these characteristics, insects possess a
unique and very efficient respiratory system. a varied and involved
biology, and t.he abi lity to partake of food in a diversity of ways.
ThIIS, in the insect world is found material worthy of man's best
efforts in study, and problems which challenge Ilim on every side.
Man's welfare is materially aITeeted in a multiplicity of ways by
insects. His body may be attacked, his food despoil d, and his dis-
eases contracted in their feeding. Most of his stored possessions and
the house in which he lives are subject to insect damage. Field crops,
livestock, fruits, timber, and other agri ultural products suffer great
losses from the depredations of insects. Yet, man is also benefittd
2
GENERAL AND APPLIED ENTOMOLOGY
in a number of ways by their presence. Many are parasites or pred-
ators of otber insects that are pests. They are useful in tbe pollina-
tion of many plants. Insects are nature's scavengers and reduce plant
and animal matter to earth mold; they are a source of food for fishes
and wildlife, and the products of some are of value in industry. On
the basis of their re lation to man, insects may be classed as either
harmful or beneficial ; however, the status of many is uncertain be-
cause their biologies are not adequately understood.
HARMFUL INSECTS
Insects and Public Health
When insect.s are considered on a world-wide basis perhaps they
are 1110st injurious to man as vectors of human diseases. Through the
ages millions of people have died of diseases transmitted by insect.s.
There are a number of insect-borne diseases, and these may be
transmitted in different ways. A few of the more illlportant may be
men tioned.
Malaria is one of the illlportaI1l diseases uf mankind. The disease
is most prevalent in tropical regions where it exacts its greatest toll
in human suffering and dea ths. The disease is transJIl itted solely by
certain species of Allopheles mos juitues. Owing to improvement of
health standards and mosquito control measures t.he disease is rarely
found in the United States today.
Yellow fever is allother dreaded disease oC tropical and subtropi-
cal regions which is l1Iosquit.o-borne. By means oC mosquito control
measures and the use of a protective vaccine the disease is kept in
check. Filariasis, dengue, and encephalitis are other diseases trans-
mitted by mosquitoes.
The pestiferous hou e Hy has developed in the wastes of man and
his animals and t.hen persistently insisted upon sharing his food
since the human race was young. Becau e of its filthy feeding and
breeding habits it may transmit by mechanical means such diseases
as typhoid. dysentery, and diarrhea.
Fleas are transmitters of buboni plague and murine typhus of
man. Bubonic plague is the Black Death of the Middle Ages that
swept away mil lions of lives in Europe and Asia. Because of the
knowledge of the disease, its transmitters and hosts, it should never
again reach the propurtions o[ a plague in civilized countries.
INTRODUCTION
3
Louse-borne typhus is anot.her scourge of the human race. The
statement has been made that more people have died of this dis-
ease than have been killed in all wars. Typhus epidemics have al-
ways followed in the \\lake of \liars due 10 lowered standards of sani-
tation and the crowding together of lllally people. This disease may
nO'lv be controIled . Other diseases transmitted by insects are men-
tioned in the text with the discussion of their vectors .
.Even though certain insects may not transmit pathog-enic organ-
isms, they may be pests through their stings. bites, and obnoxious
presence. Everyone is aCfluainted with tbe sting of 'rasps, bees, and
ants. Some ca terpillars bear Ilett ling hairs or spint's on their bodie '
which produce dermatilis and other symptoms when pressed against
the skin. Body fluids of Il1cloicl beetles contain a poisonous com-
pound, cantharidin. which produces blisters. Assassin bup and oth-
ers can inflict painful bites. Cockroaches with their nauseating odor
and ioalilsomc presence, pestiferollS g-nats. allts, and many other
insects arc nu isances of 110 mean ;mportance.
Insects and Agriculture
Plants and animals are alt.a('ked and injnred by insects in a num-
ber oC ways. In addition to t.heir f(:'ccl ing-, discases may be transmit-
ted by [hem. The LOlal loss produced by illsects 10 agricultural prod-
ucts is extrcmely diH-icult to cstimate dllc to t.hc llIany variable and
colnplicated factors involved. Perhaps th e tolal fi gure would reach
the stupendolls slim of sever(ll billions of dollars ann uall y.
A few outstanding insect pests to crops arc mentioned. The vall
weevil produced such serious economic repercussions in the South
that a revolution in the methods or production of colton was
brought about. The European corn horer COSts the fanners milli ns
of dollars annually. Grasshoppers hilve plagued fanners in this coun-
try since pioneer days. Plant lice, the chinch bug, the od ling moth,
and others too numerous to mention have exacted a huge toll. of
crops.
Insects are important veClOrS of plant diseases. Plant lice, or
aphids, and leafhoppers in particular are involved in the transmis-
sion of a large number of important virus diseases, some of which
are transmitted only by insects. Cucumber beetles are the only
known vectors of bacterial wilt of cucurbiLS. The Dutch elm disease
is spread by bark beetles.
Injury to livestock by arthropods is caused by their sucking blood.
6
GENERAL AND APPLIED ENTOMOLOGY
Insects as Pollinators
lnsects are invaluable in the pollination of plants. Some of the
higher plants are self-pollinated, but most are cross-pollinated.
Wind and insects are the chief factors in cross-pollination. Bees,
wasps, an.ts, bUllerH ies, beetles, Aies, and t.1l ri ps all render va I uable
service in the pollinat.ion of plants. "Vild bees ancl honey bees are
the most valuable pollinators. Honey bees are depended upon
mostly when the services of insect pollinators are needed in the pro-
duction of cultivated crops such as clovers, alfa lfa, apples, pears,
plums, and certain vegetables. SOllle plams, e.g., the yucca and the
Smyrna fig, are completely clependen.t lipan certain species of in-
sects for pollination.
Other Ways in ,,vhich Insects Are Beneficial
Insects are an important source of food for many animals. The
more cOlllmon birds depend largsely upon insects as a source of food
and Lhey consume huge quantities of them, especially during I.hf'
nesting season. Insects stich as bloodworms and the nymphs of may-
Hies are important as food fol' fresh-watel' fishes. Toads, frou-s, liz-
zards, skunks, armadillos, bats, and other animals also depend heav-
ily upon insects as a source of food.
Insects are sometimes referred to as n(lture's scavenger~. They are
of much aid in reducing both plant (lnd animal material to earth
mold. \"'ood-boring beetles, carpenter an.ts, termites, and other in-
sects help reduce logs, limbs, leaves, and rela.ted materials to. hu-
mus. MayAy nymphs and other aquatic insects feed on organic mat-
ter in ponds and streams, and thus help prevent pollution o[ these
waters. Many insects aid in the elimination o£ animal wastes; how-
ever, Aies which develop in su h material may do much gTeater
harm than good as disseminat.ors of diseases.
Certain insect products have considerable commercial value.
Honey has been a prized article of food since ancient days. There is
always a demand in industry for beeswax for making such products
as candles, polishes, and waxes. Silk is the product of the larva of
an insect, the silkworm. Although silk is replaced largely by syn-
thetic fibers. its product.ion is still an imponant industry in some
parts of the world. The production of shellac is a means of liveli-
hood for' a number of people, chiefly in Burma and India, Shellac
is obtained from the la scale insect.
INTRODUCTION
7
A number of insects inhabit the soil and in so doing they have
served to improve its texture S011l what, and also in some instances
add some humus. The more important soil-inhabiting forms are
ants and termites. Others are solitary bees and wasps which ('on-
Slruct their nests in the soi I, grubs of beetles, nymphs of some spe-
cies, and larvae of certain flies.
Insects feed on weeds as well as other plants and they may aid
materially in keeping them in check. T he most sllccess[u l lise of an
insect in the control of a plant was the introduction of the cater-
pillar of a moth (Cactnhlas/is cne/orum ) to control the prickly pear
(()jJllrllia spp.) in Austra lia.
10
GENERAL AND APPLIED ENTOMOLOGY
With one pair or no antennae; primarily terrestrial in habi-
tat; breathe by means of air tubes, book lungs, or body wall
2
2. With no antennae and four pairs of legs (Spiders, Scorpions,
and Ticks)
Arachnida, p. 11
With oTle pair of antennae and three or more pairs of legs
3
:l. With three pairs of legs and usually two pairs of wings
(Insects)
Hexapoda, p. 35
With more than three pairs of legs and no wings
IJ
4. With one pair of legs on each body seglllent (Centi-
pedes)
Chilopoda, p. ~H·
With two pairs of legs on each body segment (Milli-
pedes)
Diplopoda, p. 33
CLASS CRUSTACEA (CRAYFISH, SHRIMPS, AND OTHERS)
The members of t.his class breathe by means of gi lls with the ex-
ception of small forms that respire t.hrough the body wall. They are
aquatic. or at least live in a moist environment. Two pairs of an-
tennae are generally present on the head, and a number of pairs of
legs, often modified ror swimming, are attached to the body. In a
111111lber of cases, some of the body segments are fused wit.h the head
to form a cephalolhorax (head-thorax).
Crustacea (Fig. I ) are represented by such common forms as
crayfish, lobsters, pill bugs, sow bugs, crabs, and shrimps. They live
mostly in seas and fresh waters where they feed chieHy as scaven-
gers on decaying veget.able and an imal mat.ter. The bulk of the zo-
oplankton mat.erial in water consists of smal l crustacean life.
Crustaceans supply much of the fish food; and they are also a source
of food for man (e.g., lobsters, shrimps, and crabs).
On the whole, Crustacea are considered beneficial but there are
some harmful species. Barnacles, sessile marine forms, do much
damage to shore installat.ions and impede the speed of ships by at-
taching themselves to the bottom of the vessels. On rare occasions
crayfish have been known to damage lawns and destroy field crops
in humid regions where the soils have exceptionally high water lev-
els. Sow bugs and pill bugs are pests in greenhouses, flower beds,
and garden . Sow bug and pill bugs may be controlled with DDT
dusts and poison baits. Certain species of Cyclops serve as host.~ of
the broad tapeworm (Dij)hyllobothrium. [alum.) and the guinea
worm (Dmcunculus rnedinensis).
INSECTS AND RELATED ANIMALS
11
CLASS ARACHNIDA (SPIDERS, SCORPIONS, AND TICKS)
1 his lass includes such (ommon forms as spiders, scorpiolls, ticks.
and mi tes. The bodies of members of this group are usna lly com-
posed of two divisions, tbe cephalothorax and abdolllen. Antennae
are absent and eyes are simple. Four pai rs of kgs are attached 10
the cephalothorax in the adult stage. The class is terrestrial, breath-
ing by air tubes and book lungs.
Arachnida are divided into a number of orders. T he following
key will aid the student in recognizing members of the more com-
mon orders.
KEY TO COMMON ORDERS OF ARACHNIDA
J. Abdomen with distinel segm en ts
2
Abdomen not distinctly segmented
6
2. Abdomen with tai l-like prolonga tion
3
Abdomen with no tail-like prolongation
'I
3. Tail stout and terminating in a sting (Scorpions)
Scorpionida, p. 1,1
Tail long and slender wi lhom sting ("Vhip Scorpions)
Pedipalpida, p. 15
4. Palpi armed with pincer-like claws (Psc udoscorpiolls)
Chelonethida (l>seudoscorpionida), p. 17
Palpi without pincer.like claws
.')
5. Abdomen auached to cepha lolhorax by a slender stalk
(Whip Scorpions)
Pedipalpida, p. I G
Body ova l and olllpact; legs usually quile long (Han-estm en
Or Daddy-long-legs)
Phalangida. p. 18
6. Cephalothorax and abdomen joined by short stal k (Spiders)
Araneida, p. II
Cephalothorax and abdomen broadly joined (Mites and
Ticks)
Acarina, p. 18
Order ARANEIDA (Spiders)
This is the largest order of Arachnida and several thousand spe-
cies are represented in North America fauna. Although a few spe-
cies are poisonous to man, the group as a whole must be considered
beneficial as its members prey chiefly upon insects.
Spiders (Fig. 2) may be readi ly separated from other Arachnida
in having an unsegmented abdomen attached to the cephalothorax
12
GENERAL AND APPLIED ENTOMOLOGY
by means of a slender stalk or pedicel. There are usually twO to
eight simple eyes. but in some cave-inhabiting forms eyes may be
absent. Mouthparts consist of paired dU'licera e and a pair of: IJaljJi
(ped ipalpi). The chelicerae represent the modified second anten-
nae of the Crustacea. Spiders do not devour their prey but. cTUsh it
and suck the body fluids by means of a so-called sucking stomach .
The palpi of the female are leg-l ike structures. but th ey are en-
larged and modified in the male for use in tranSFerring perm to
the fema le in mating. On the ventra l surface of the abdomen are
loca t.ed the spinnerets (si lk-spinning organs). Opening on the spin-
nerets are fOLlr types of tubes through which is spun fOllr kinds of
si lk, each of which is uti lized for a dilTcrent plll'posc. Anterior to
the spinnerets is a single spiracle. Rook lungs arc accessory respira-
FlC. 2.
A wolf spider. (From Illinois Natura l History Survey. Dr""," by C. O.
Mohr.)
tory organs. They arc sacs cont.aining plates arranged as the leaves
of a hook. One or tll'O pairs o l~ book lungs are found in spiders and
their openings are llsually located on each side of the gen ital open-
lI1g.
Spiders capture their prey by different means. Some species, such
as jllmping spiders and wolf spiders. sta lk their victims. Crab spi-
ders hide in Howers and pounce upon the insect visitors. Most spi-
ders spin si lkell webs of some type in which their insect prey is
snared. The webs are of various types. characteristic of the spider
gTOUp. T he orb-weaver spin the well known orb webs. House spi-
ders construct irregular webs. Others make funnel or triangular
webs. When the prey is captured it is u 'ually killed by t.he poison of
the bite.
INSECTS AND RELATED ANIMALS
13
The mating habits of spiders are of interest. to biologists. The
males are generally smaller than the females and can be recognized
by t.he enlarged and modified pal pi. In some species mating. is pre-
ceded by a courtship performance by the males which attempt to
illlpress the females by dan ing, circling, and showing off in olh r
ways. Sometimes the females join in the performance. In many spe-
cies the females may ki ll and cat the males following mating. T his
is why the black widow spider is so named.
The fema le spider Jays her eggs in a silken sac. Great care is taken
of th e eggs and young spiders. The sac containing the eggs may be
carried by the female or attached to some object. Some young spi-
ders are canniba l istic and d vour the weaker individuals.
As spiders are wingless they m llst depend upon means other than
Hight for dispersion. They may crawl or be transported by oth r ani-
mals or by air currents. Young spiders frequ ently make use of air
currelllS for dispersion, especially in the auturnn. They crawl to a
high point, elevate the abdomen and spin out silken strands. When
the silken t.hreads create sufficient bouyancy in the breeze the spi-
der is carried away, frequent ly to considerable distances. Strands of
silk lioating through the air on clear autumn days are as much a
part of the season as Hocks of wi ld geese on their southward journey.
Spiders are feared beca use of their bites. It is difficult to induce
most of them to bite, and only a few of the North American spe-
cies are poisonous to !llano Only the bite of the black widow spiel r
(La./ror/ec/lIs 1I7flc/,am )
i.~ dangerously poisonous. Spiders bite with
the chelicerae (fang's), which are normally provided with poison
glands.
The Black W idow Spider (La ITodect.us macta.lls). The mature
female black wide w spider (Fig. 3) is deep black with reel markings
in the form of an hourglass 011 the underside of t.he abdomen. It
measures about Ih inch in length. The male is much smaller tban
the fema le. The abdomen of the male is marked dorsally with three
transverse white bands and a median red stripe. It has enlarged and
rnodified palpi . The males are relatively short-lived.
The black widow spider is most frequently found where insects
are abundant. During the summer it is quite commonly found un-
derneath bee hives. Occasionally it becomes relatively numerous
where flies fTeq uent.
The poison at t.he black widow spider is reported to be a neuro-
toxin. Man, however, is seldom bitten by this spider. When bilten,
