ARTHROPODSOFFLORIDAANDNEIGHBORINGLANDAREASVOLUME2THEWIDOWSPIDERSOFFLORIDAJohnD.McCroneKarl J. StoneFLORIDADEPARTMENTOFAGRICULTUREDoyle Conner, CommissionerDIVISIONOFPLANTINDUSTRYHalwinL.Jones, Director Single copies free to Florida residentsonrequest to Florida Department of Agriculture Division of Plant Industry Library Post Office Drawer 1269 Gainesville, Florida32601


/'FLORIDADEPARTMENTOFAGRICULTUREDoyleConner,CommissionerDIVISIONOFPLANTINDUSTRYPlantIndustryTechnicalCommitteeVernonConner,ChairmanMountDoraRoyVandegrift,Jr.,ViceChairmanCanalPointColinEnglish,SrTallahasseeW.R."Bill"McMullenTampaN.CurtisPeterson,JrLakelandStuartSimpsonMonticelloFosterShiSmithStarkeFelixH. Uzzell SebringHalwin L.Jones,SecretaryGainesvilleAdministrativeStaffHalwin L.Jones,Division Director GainesvilleP.E.Frierson,AssistantDirector Gainesville V.W.Villeneuve,FiscalOfficer Gainesville R.E.Hancock,InformationOfficer Gainesville H. A.Denmark,Chief,EntomologySection GainesvilleG.G.Norman,Chief, MethodsDevelopmentSectionWinterHavenP.M.Packard,Chief,ApiarySection GainesvilleC.P.Seymour,Chief,PlantPathologySection GainesvilleC.E.Shepard,Chief,PlantInspectionSection Gainesville (Unfilled), Chief,NematologySectionGainesville


FOREWORDEntomologists oftheDivision ofPlantIndustry,Florida Department of Agriculture, provideanidentification service fortheState of Florida of insects, mites, spiders, scor pions, millipedes, centipedes,andotherar thropods. Spiders, particularly, seemtoarousethecuriosity ofmanypeople whosubmitspecimens for identificationandrequestcontrol recommendations. Likethe,snakes,spidersarelittleunderstoodand muchmaligned bymostpeople, usually with littleornojustification.Sofar as known, withtheexception ofthemembers of two small families, all spidershavepoison glands. Thevenomisusedto killtheirprey }':f andas a means of defense. However, only a few species,suchas certaintarantulasandotherspiders ofthetropics, produce a venomvirulentenoughtobe harmful to man. More over,mostspecies are too timid and donotattemptto bite evenwhenhandled roughly. '--YIn Florida, onlythespiders belongingtothegroup commonly called widowsarecapable of inflicting a bite serioustoman. The bite '. ofthelarger wolf spidersandthefearsome looking silk spider is little worsethanthestingof a bee or wasp. Mostothernative spiders seldom bite man,andmanyare in capable of doing so. Whiletheincidence of bites by widow spiders isnothigh,thewidow spiders are fairly commoninFlorida,andquestions regardingthemare received frequently bytheentomologists oftheDivision ofPlantIndustrywho curatetheFlorida State Collectionof Arthropods. The seriousness ofthebite of amaturefemale widow spider sug geststhatthegeneral publicshouldbe cor rectly informed concerning this groupofspiders, includingtheirpromptrecognitionandthetreatmentsrecommended for bites.TheWidowSpiders'ofFloridaisthesec ondinanirregularlyappearing series of publications relating to the insectsandotherarthropods of Floridaandneighboringlandareas-thesoutheasternUnited States,theBahamaIslands,theGreaterandLesserAn tilles,andthelandareasinandroundtheGulf ofMexico-withemphasisontaxonomy, ecology, biology,andzoogeography. Empha sisinthis series, initiated earlyin1965withthepublication ofLepidopteraofFloridabyC.P.Kimball, isontheFlorida fauna. HowardV.Weems,Jr.EditorEntomology Section Division ofPlantIndustryFlorida Department of Agriculture Gainesville, Florida March1,1965


FEMALEWIDOWSPIDERSSouthernBlack Widow,Latrodectus mactans(Fabricius) Note completehourglass(PhotobyH.W.Levi)NorthemBlackWidow,Latrodectus variolusWalckenaer Notebrokenhourglass(PhotobyH.K. Wallace) Brown Widow,Latrodectus geometricusC.L. Koch(PhotobyH.W. Levi) Brown Widow.Latrodectus geometricusC.L.Koch(PhotobyH.K. Wallace) Red Widow,Latrodectus bishopiKaston(PhotobyH.K. Wallace)SouthernBlack Widow.Latrodectusmactans(Fabricius)(PhotobyJ.D.McCrone)


THE WIDOW SPIDERS OF FLORIDAJohnD.McCrone2KarlJ.Stone 3 Introduction:There are four species oftheblack widowgenusLatrodectusthatare known to occurinFlorida:thesouthernblack widow,Latrodectus mactans(Fabri cius);thenorthernblack widow,L.variolusWalckenaer;thered widow,L.bishopiKas ton;andthebrown widow,L.geometricusC.L. Koch. Sincetheimmatures andtheadultmaleLatrodectusdonotpose a publichealthproblem, descriptionsinthis publica tion are limited tothemature females. Males cannot be identified to species easily.The Genus:The spidersinthisgenusare fairly large,theoveralllengthwith legs ex tended is aboutlY2inches.Theyhave a smallcephalothoraxand alarge,high, smooth, subglobose abdomen. Althoughthewhole body is densely covered withshortalmost microscopic hairs,thespiders have ashinynaked appearance. Some ofthecharac ters used to separatethespecies are difficult to see without a microscope and special tech niques. When possible, specimens should be capturedandplacedina vialorbottle of70%alcohol,suchas rubbing alcohol,andsubmitted for positive identification by a specialist. Fortunately', however,inFloridaitis possible to identifymostadult female specimens bymeansof their distinctive color patterns. LATRODECTUS MACTANS,TheSouthern Black WidowIdentification:The body is glossy black to sepia. The dorsum oftheabdomen is usually free of markings,althoughoccasionallythereareremnantsoftheimmature color pattern. There is a red hourglass marking ontheven-1Contribution No.53,Entomology Section, Divi sion ofPlantIndustry2AssociateProfessorof Biology, Florida PresbyterianCollege, St.Petersburg,Florida 3Entomologist, Division 'ofPlantIndustry,Florida Department of Agriculture, Gainesville, Florida.teroftheabdomenanda red spot ontheposterior end oftheabdomenjustabovethespinnerets.Distribution:This isthemostwidespread species ofthegenusinFlorida. Ithas beentakeninmostcountiesandprobably occursinall of them. Theotherspecies have more limited distributions.HabitatandLifeHistory:Thesouthernblack widow occupies a large variety of habi tats, usuallynearhumanhabitation orinnewly disturbed areas.Itmakesanirregular web of verytoughsilkinsuchprotected places as stumps, discarded pipe and buildingmaterials,understones,instorm sewersandwatermeterboxes,andunderpark benchesandtables.Itis seldom foundinhousesinFlorida. Connected totheweb is a small silken retreat.InFlorida, this spiderhasnowell defined breeding cycle, andallstages of development can be foundatanytime. The females make several egg sacs duringanextendedperiod aftermating.Theseegg sacs are pear-shapedtoalmost globular, andthetoughpaperyoutercoveringrangesincolor from white to tan. Each sac contains from onehundredto severalhundredyellowish eggs. Often these eggs havebeenparasitizedeitherbydipterousorhymenopterous egg parasites.Inaddition to parasites,themainfactors limiting popula tion size are extreme climatic conditionssuchas extremelyhighorlow humidity and freezing. LATRODECTUS VARIOLUS, TheNorthernBlack WidowIdentification:This specieshasthesame general appearance asL.mactans.Itdiffersinthatthereis a median longitudinal row ofredspotsonthedorsum oftheabdomen, andontheventerthereare two transverseredbars instead ofanhourglass.Distribution:InFlorida,L.variolushasbeen found only west of Tallahassee.Itis


particularlyabundantinthevicinity of Tor reyaState Park.HabitatandLifeHistory:Thenorthernblack widow isfoundinmesicandxeric hammocks wheretheadults make websinthebranches of trees.Thesewebs occurinarangeof3-20feet offtheground. A dome shapedretreatis locatedintheleavesattheendof a branch,andtreads radiateouttoone or more branches. UnlikeL.mactans,L.variolushas a well defined breeding cycle. During MarchandApril,immaturespidersarewidely scatteredinforest litter,andinlatespring, adultsarefoundinthetrees. Mating occursandthemales die immediately afterward. Duringthesummer,adultfemales arefoundintheretreatswith oneormore egg sacs which are similartothoseofL.mactans.By late fall all adults are gone, andverysmall immatures are foundintheforest litter.LATRODECTUS BISHOPI,TheRed WidowIdentification:Thecephalothoraxandlegs arereddishorange. The entire abdomen may be black,ormayhavedorsalmedianredspots or dorsal red spotssurroundedby a yellow border, whiletheventer,lacking a complete hourglass, mayhaveoneortwo red spots.Distribution:This specieshasaveryre stricted distribution.Ithasbeenfoundonlyinsand-pine scrub associationsincentral andsoutheasternFlorida.HabitatandLifeHistory:Thered widow almost always makes its web off thegoundinpalmettos In sahd-pine scrub.Thewebretreatis made by taking a palmetto frond and rollingitintoa cone.Theinteriorofthecone is lined with silkandtheegg sacs arehungfromthesides ofthecone. The egg sacs arelightgraytowhiteincolorandhave a fairly softoutercovering unlikethepapery covering ofL.mactansandL.vari olus.Thethreadsoftheweb spread from frond to frond ofthepalmettosandform a sheet-likepattern.Adults are found all year.LATRODECTUS GEOMETRICUS,TheBrown WidowIdentification:This species variesincolor fromlightgraytolightbrown or even al mostblack.Thedorsum oftheabdomenhasa highly variablepatternconsisting of black, white, red, and yellow markings. Ontheventerisanhourglass which is orangeoryellowishredincolor.Distribution:L.geometricusis cosmotropi cal.Itprobably was introduced into Floridaandismostabundantincoastal citiesinthelowerpartofthepeninsula,buta fewhavebeenfound as farnorthas Daytona Beach.HabitatandLifeHistory:The brown wid ow is quiteabundantinsomeofthecoastal cities ofsoutheasternFlorida.Itusuallymakes its webonbuildingsinwell lighted areas. Service stations are particularly good places to find them. The webs are somewhat likethoseofL.mactansbutare smaller, whilethesilk isnotastoughandtheweb bing is very dirtyandunkempt.Theegg sacs appear very diffl!rent fromthoseofotherLatrodectussp.Insteadofbeingsmooth,theoutside oftheegg sac is covered with little papules. Adults arefoundall year,andtheredoesnotseemtobe any definite breeding cycle. Medical Importance All four specieshaveverypotentvenoms,butfor a variety of reasons, onlyL.mactansis likely to be involvedina spider bite caseinFlorida.Ifanindividual isbittenbyoneoftheotherspecies,thesame measures recommended forL.mactansbitesshouldbe taken.Thebite ofL.mactansproduces asharppainsimilartoa needlepuncture.Usually this pain disappears rapidly,butitmay per sist forhours.Local muscular cramps are felt15minutesto severalhoursafterthebite.Themusclesmostfrequently affectedarethose-inthethigh, shoulder, and back.Laterseverepainspreadstotheabdomen,andthereis weaknessandtremor.Theab dominal muscles show a boardlike rigidity.


Respiration becomes spasmodic,andthepatientis restlessandanxious. During this period a feeble pulse, cold clammy skin, laboredbreathingand speech,lightstupor,anddelirium may be noted. Convulsions,urinaryretention,shock, cyanosis,nauseaandvomiting, insomnia, and cold sweats alsohavebeenreported. Local measures,suchas thoseusedfor snakebite, donotseem to be effective becausethevenomspreads very rapidly. Medi caltreatmentshouldbesoughtimmediately,andthepatientshould be keptquietandplacedinbed assoonas possible. One vial of Lyovac antiveninshouldbe administeredtopatientsunder14years of age. The acutepainofthemuscle spasmsmaybe relieved by prolonged warm baths, hydrotherapy,ortheintravenousinjection of10%calcium gluconate. Recently,intravenousinjection of10mlof methocarbamol (Robaxine) over a 5-minute period, followed by slow intravenousdrip ofthedruginsodium chloride,hasproved to be very effective. Deathmayoccur fromthevenom, dependinguponthevictim's physical condition, age, andthelocation ofthebite. Complicatingfactorssuchassyphilis,heartdisease,and/orkidney disease coupledwiththeven om may produce a fatality. Adults are moreresistanttopoisonthanchildren,butindi vidual sensitivitymayenhanceordepressthereaction ofbothage groups.Theonly caseonrecord of ahealthyadultbeing killed bythevenomis oneinwhichthevic tim was bittenatthebase oftheskull, there by givingthebrain apotentandrapid dose of venom.ControlSpidersandegg sacsmaybe crushed with a broom,andanydebristhatharborsthespidersshouldbe cleared away. Fiveto10%DDTor2%lindanecan beusedto controlthesespiders. BHCusedin closed areasattherateof1/6oz.of the productper130cu. yds. isthemosteffective insecticide. Treatmentshould be repeated after30daystodestroyanybroods whichhaveemerged.ACKNOWLEDGMENTSAppreciation is expressed to Dr. ThomasJ.Walker,Jr.,Department of Entomology, University of Florida, for editingthetext; Dr. HowardK.Wallace,DepartmentofZoology, University of Florida,andDr. Herbert L. Levi, Museum of Comparative Zoology, Harvard University, for loans of photos;andMr. Edward L. Wells, Division ofPlantIn dustry, for photographic assistance.


DateDueSELECTED BIBLIOGRAPHY1.Baerg,W.J.1954.The brown widowspidersinJamaica(Araneae,Theri diidae).Ann.Ent.Soc. Amer. 47(1):52-60.2.Baerg,W.J.1959.Theblack widowandfiveothervenomousspidersintheUnitedStates.Ark.Agr. Exp. Sta. Bull.608:2-43.3.D'Amour,F.E.,F.E. Becker,andW.VanRiper.1936.Theblack widow spi der. Quart. Rev. BioI. 11(2):123-1604.Herms,W.B.,S.F.Bailey,andB.McIvor.1935.Theblack widow spider. Calif. Agr. Exp. Sta.Bull.591:1-306.Levi, H.W.1959.ThespidergenusLatro dectus(Araneae,Theridiidae).Trans.Amer.Microscop. Soc. 78(1):7-42.7.McCrone,J.D.1964.ComparativelethalityofseveralLatrodectusvenoms.Toxicon2:201-203.8.McCrone,J.D.,andH.W.Levi.1964.NorthAmericanwidowspidersoftheLatrodectuscuracaviensisgroup(Aran eae:Theridiidae).Psyche71(1):12-27.9.Parrish,HenryM.1963.Analysisof460fatalities fromvenomousanimalsintheUnitedStates.Amer.Jour.Med. Sci.245(2):129-141.5.Kaston,B.J.1938.Notesonanewvari-10.Russell, E.1961.Injuriesbyvenomousetyof black widowspiderfromsouth-animalsintheUnitedStates.Jour.ernFlorida.FloridaEnt.21(4):60-62.Amer.Med. Assoc.177(13):85-88.



The widow spiders of Florida
Full Citation
Permanent Link:
 Material Information
Title: The widow spiders of Florida
Series Title: Arthropods of Florida and neighboring land areas
Physical Description: 1 v. (unpaged) : col. ill. ; 27 cm.
Language: English
Creator: McCrone, John D
Stone, Karl J ( joint author )
Florida -- Division of Plant Industry
Publisher: Florida Dept. of Agriculture, Division of Plant Industry
Place of Publication: Gainesville
Publication Date: <1965>
Subjects / Keywords: Spiders -- Florida   ( lcsh )
Arachnida -- Florida   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Bibliography: Includes bibliography.
Additional Physical Form: Electronic version available on the World Wide Web as part of the Linking Florida's Natural Heritage Collection.
Statement of Responsibility: by John D. McCrone and Karl J. Stone.
 Record Information
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA0024
notis - AAA8757
alephbibnum - 000007326
oclc - 01736905
Classification: lcc - QL434 .A75 vol.2
System ID: UF00000082:00001


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John D. McCrone
Karl J. Stone






John D. McCrone
Karl J. Stone

Doyle Conner, Commissioner
Halwin L. Jones, Director

Single copies free to Florida residents on request to
Florida Department of Agriculture
Division of Plant Industry Library
Post Office Drawer 1269
Gainesville, Florida 32601

Doyle Conner, Commissioner


Plant Industry Technical Committee

Vernon Conner, Chairman....................................................Mount Dora

Roy Vandegrift, Jr., Vice Chairman ....................................... Canal Point

Colin English, Sr ................................................................... Tallahassee

W. R. "Bill" McMullen ............................................................Tampa

N. Curtis Peterson, Jr. ...................................................... Lakeland

Stuart Simpson.............................................. ....................Monticello

Foster Shi Smith.................................................. .....................Starke

Felix H . Uzzell ............................................................................ Sebring

Halwin L. Jones, Secretary ..................................................... Gainesville

Administrative Staff

Halwin L. Jones, Division Director ......................................... Gainesville

P. E. Frierson, Assistant Director........................................... Gainesville

V. W. Villeneuve, Fiscal Officer .............................................Gainesville

R. E. Hancock, Information Officer.........................................Gainesville

H. A. Denmark, Chief, Entomology Section...............................Gainesville

G. G. Norman, Chief, Methods Development Section ..........Winter Haven

P. M. Packard, Chief, Apiary Section.......................................Gainesville

C. P. Seymour, Chief, Plant Pathology Section........................Gainesville

C. E. Shepard, Chief, Plant Inspection Section........................Gainesville

(Unfilled), Chief, Nematology Section .................................Gainesville


Entomologists of the Division of Plant In-
dustry, Florida Department of Agriculture,
provide an identification service for the State
of Florida of insects, mites, spiders, scor-
pions, millipedes, centipedes, and other ar-
thropods. Spiders, particularly, seem to
arouse the curiosity of many people who
submit specimens for identification and re-
quest control recommendations. Like the
snakes, spiders are little understood and
Such maligned by most people, usually with
little or no justification. So far as known,
with the exception of the members of two
ssmall families, all spiders have poison
i glands. The venom is used to kill their prey
and as a means of defense. However, only a
few species, such as certain tarantulas and
other spiders of the tropics, produce avenom
virulent enough to be harmful to man. More-
over, most species are too timid and do not
attempt to bite even when handled roughly.
In Florida, only the spiders belonging to the
Group commonly called widows are capable
of inflicting a bite serious to man. The bite
of the larger wolf spiders and the fearsome
looking silk spider is little worse than the
Sting of a bee or wasp. Most other native
spiders seldom bite man, and many are in-
Scapable of doing so.
While the incidence of bites by widow
spiders is not high, the widow spiders are

fairly common in Florida, and questions
regarding them are received frequently by
the entomologists of the Division of Plant
Industry who curate the Florida State Collec-
tion of Arthropods. The seriousness of the
bite of a mature female widow spider sug-
gests that the general public should be cor-
rectly informed concerning this group of
spiders, including their prompt recognition
and the treatments recommended for bites.
The Widow Spiders of Florida is the sec-
ond in an irregularly appearing series of
publications relating to the insects and other
arthropods of Florida and neighboring land
areas-the southeastern United States, the
Bahama Islands, the Greater and Lesser An-
tilles, and the land areas in and round the
Gulf of Mexico-with emphasis on taxonomy,
ecology, biology, and zoogeography. Empha-
sis in this series, initiated early in 1965 with
the publication of Lepidoptera of Florida by
C. P. Kimball, is on the Florida fauna.

Howard V. Weems, Jr.
Entomology Section
Division of Plant Industry
Florida Department of Agriculture
Gainesville, Florida
March 1, 1965

S - y


\h: f'

Southern Black Widow,
Latrodectus mactans (Fabricius)
Note complete hourglass
(Photo by H.W. Levi)

Brown Widow,
Latrodectus geometricus C.L. Koc
(Photo by H.W. Levi)

Red Widow,
r tj� d t > iho i Kaston


Northern Black Widow,
Lotrodectus various Walckenaer
Note broken hourglass
(Photo by H.K. Wallace)

Brown Widow,
ch Latrodectus geometricus C.L. Koch
(Photo by H.K. Wallace)

Southern Black Widow,
. L trvdtui s mann...a (fahriciau )

aro --k - ps
(Photo by H.K. Wallace) (Photo by J.D. McCrone)

John D. McCrone 2
Karl J. Stone3

Introduction: There are four species of the
black widow genus Latrodectus that are
known to occur in Florida: the southern
black widow, Latrodectus mactans (Fabri-
cius); the northern black widow, L. various
Walckenaer; the red widow, L. bishop Kas-
ton; and the brown widow, L. geometricus
C. L. Koch. Since the immatures and the
adult male Latrodectus do not pose a public
health problem, descriptions in this publica-
tion are limited to the mature females. Males
cannot be identified to species easily.
The Genus: The spiders in this genus are
fairly large, the overall length with legs ex-
tended is about 11/2 inches. They have a
small cephalothorax and a large, high,
smooth, subglobose abdomen. Although the
whole body is densely covered with short
almost microscopic hairs, the spiders have a
shiny naked appearance. Some of the charac-
ters used to separate the species are difficult
to see without a microscope and special tech-
niques. When possible, specimens should be
captured and placed in a vial or bottle of
70% alcohol, such as rubbing alcohol, and
submitted for positive identification by a
specialist. Fortunately, however, in Florida
it is possible to identify most adult female
specimens by means of their distinctive color

Black Widow

Identification: The body is glossy black to
sepia. The dorsum of the abdomen is usually
free of markings, although occasionally there
are remnants of the immature color pattern.
There is a red hourglass marking on the ven-

1Contribution No. 53, Entomology Section, Divi-
sion of Plant Industry
2Associate Professor of Biology, Florida Presby-
terian College, St. Petersburg, Florida
3Entomologist, Division of Plant Industry, Florida
Department of Agriculture, Gainesville, Florida.

ter of the abdomen and a red spot on the
posterior end of the abdomen just above
the spinnerets.
Distribution: This is the most widespread
species of the genus in Florida. It has been
taken in most counties and probably occurs
in all of them. The other species have more
limited distributions.
Habitat and Life History: The southern
black widow occupies a large variety of habi-
tats, usually near human habitation or in
newly disturbed areas. It makes an irregular
web of very tough silk in such protected
places as stumps, discarded pipe and build-
ing materials, under stones, in storm sewers
and water meter boxes, and under park
benches and tables. It is seldom found in
houses in Florida. Connected to the web is
a small silken retreat. In Florida, this spider
has no well defined breeding cycle, and all
stages of development can be found at any
time. The females make several egg sacs
during an extended period after mating.
These egg sacs are pear-shaped to almost
globular, and the tough papery outer cover-
ing ranges in color from white to tan. Each
sac contains from one hundred to several
hundred yellowish eggs. Often these eggs
have been parasitized either by dipterous or
hymenopterous egg parasites. In addition to
parasites, the main factors limiting popula-
tion size are extreme climatic conditions
such as extremely high or low humidity and

Black Widow

Identification: This species has the same
general appearance as L. mactans. It differs
in that there is a median longitudinal row
of red spots on the dorsum of the abdomen,
and on the venter there are two transverse
red bars instead of an hourglass.
Distribution: In Florida, L. various has
been found only west of Tallahassee. It is

particularly abundant in the vicinity of Tor-
reya State Park.
Habitat and Life History: The northern
black widow is found in mesic and xeric
hammocks where the adults make webs in
the branches of trees. These webs occur in
a range of 3-20 feet off the ground. A dome-
shaped retreat is located in the leaves at the
end of a branch, and treads radiate out to
one or more branches. Unlike L. mactans,
L. various has a well defined breeding cycle.
During March and April, immature spiders
are widely scattered in forest litter, and in
late spring, adults are found in the trees.
Mating occurs and the males die immediately
afterward. During the summer, adult females
are found in the retreats with one or more
egg sacs which are similar to those of L.
mactans. By late fall all adults are gone, and
very small immatures are found in the forest


Identification: The cephalothorax and legs
are reddish orange. The entire abdomen may
be black, or may have dorsal median red
spots or dorsal red spots surrounded by a
yellow border, while the venter, lacking a
complete hourglass, may have one or two
red spots.
Distribution: This species has a very re-
stricted distribution. It has been found only
in sand-pine scrub associations in central
and southeastern Florida.
Habitat and Life History: The red widow
almost always makes its web off the gound
in palmettps in sand-pine scrub. The web
retreat is made by taking a palmetto frond
and rolling it into a cone. The interior of
the cone is lined with silk and the egg sacs
are hung from the sides of the cone. The
egg sacs are light gray to white in color and
have a fairly soft outer covering unlike the
papery covering of L. mactans and L. vari-
olus. The threads of the web spread from
frond to frond of the palmettos and form a
sheet-like pattern. Adults are found all year.


Identification: This species varies in color
from light gray to light brown or even al-
most black. The dorsum of the abdomen has
a highly variable pattern consisting of black,
white, red, and yellow markings. On the
venter is an hourglass which is orange or
yellowish red in color.
Distribution: L. geometricus is cosmotropi-
cal. It probably was introduced into Florida
and is most abundant in coastal cities in the
lower part of the peninsula, but a few have
been found as far north as Daytona Beach.
Habitat and Life History: The brown wid-
ow is quite abundant in some of the coastal
cities of southeastern Florida. It usually
makes its web on buildings in well lighted
areas. Service stations are particularly good
places to find them. The webs are somewhat
like those of L. mactans but are smaller,
while the silk is not as tough and the web-
bing is very dirty and unkempt. The egg
sacs appear very different from those of
other Latrodectus sp. Instead of being
smooth, the outside of the egg sac is covered
with little papules. Adults are found all year,
and there does not seem to be any definite
breeding cycle.

Medical Importance

All four species have very potent venoms,
but for a variety of reasons, only L. mactans
is likely to be involved in a spider bite case
in Florida. If an individual is bitten by one
of the other species, the same measures
recommended for L. mactans bites should
be taken.
The bite of L. mactans produces a sharp
pain similar to a needle puncture. Usually
this pain disappears rapidly, but it may per-
sist for hours. Local muscular cramps are
felt 15 minutes to several hours after the
bite. The muscles most frequently affected
are those in the thigh, shoulder, and back.
Later severe pain spreads to the abdomen,
and there is weakness and tremor. The ab-
dominal muscles show a boardlike rigidity.

Respiration becomes spasmodic, and the pa-
tient is restless and anxious. During this
period a feeble pulse, cold clammy skin,
labored breathing and speech, light stupor,
and delirium may be noted. Convulsions,
urinary retention, shock, cyanosis, nausea
and vomiting, insomnia, and cold sweats also
have been reported.
Local measures, such as those used for
snakebite, do not seem to be effective be-
cause the venom spreads very rapidly. Medi-
cal treatment should be sought immediately,
and the patient should be kept quiet and
placed in bed as soon as possible. One vial
of Lyovac antivenin should be administered
to patients under 14 years of age. The acute
pain of the muscle spasms may be relieved
by prolonged warm baths, hydrotherapy, or
the intravenous injection of 10% calcium
gluconate. Recently, intravenous injection
of 10 ml of methocarbamol (Robaxine) over
a 5-minute period, followed by slow intra-
venous drip of the drug in sodium chloride,
has proved to be very effective.
Death may occur from the venom, depend-
ing upon the victim's physical condition,

age, and the location of the bite. Complicat-
ing factors such as syphilis, heart disease,
and/or kidney disease coupled with the ven-
om may produce a fatality. Adults are more
resistant to poison than children, but indi-
vidual sensitivity may enhance or depress
the reaction of both age groups. The only
case on record of a healthy adult being
killed by the venom is one in which the vic-
tim was bitten at the base of the skull, there-
by giving the brain a potent and rapid dose
of venom.


Spiders and egg sacs may be crushed with
a broom, and any debris that harbors the
spiders should be cleared away. Five to 10%
DDT or 2% lindane can be used to control
these spiders. BHC used in closed areas at
the rate of 1/6 oz. of the product per 130 cu.
yds. is the most effective insecticide. Treat-
ment should be repeated after 30 days to
destroy any broods which have emerged.


Appreciation is expressed to Dr. Thomas L. Levi, Museum of Comparative Zoology,
J. Walker, Jr., Department of Entomology, Harvard University, for loans of photos; and
University of Florida, for editing the text; Mr. Edward L. Wells, Division of Plant In-
Dr. Howard K. Wallace, Department of Zo- dustry, for photographic assistance.
ology, University of Florida, and Dr. Herbert

Date Due


1. Baerg, W. J. 1954. The brown widow
spiders in Jamaica (Araneae, Theri-
diidae). Ann. Ent. Soc. Amer. 47(1):

2. Baerg, W. J. 1959. The black widow and
five other venomous spiders in the
United States. Ark. Agr. Exp. Sta. Bull.
608: 2-43.

3. D'Amour, F. E., F. E. Becker, and W.
Van Riper. 1936. The black widow spi-
der. Quart. Rev. Biol. 11(2): 123-160

4. Herms, W. B., S. F. Bailey, and B. Mc-
Ivor. 1935. The black widow spider.
Calif. Agr. Exp. Sta.Bull. 591: 1-30

5. Kaston, B. J. 1938. Notes on a new vari-
ety of black widow spider from south-
ern Florida. Florida Ent. 21(4): 60-62.

6. Levi, H. W. 1959. The spider genus Latro-
dectus (Araneae, Theridiidae). Trans.
Amer. Microscop. Soc. 78(1): 7-42.

7. McCrone, J. D. 1964. Comparative lethal-
ity of several Latrodectus venoms.
Toxicon 2: 201-203.

8. McCrone, J. D., and H. W. Levi. 1964.
North American widow spiders of the
Latrodectus curacaviensis group (Aran-
eae: Theridiidae). Psyche 71(1): 12-27.

9. Parrish, Henry M. 1963. Analysis of 460
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10. Russell, E. 1961. Injuries by venomous
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