UF/IFAS Okeechobee County Extension Service

458 Highway 98 North

Okeechobee, FL 34972-2578

Phone: (863) 763-6469

E- mail:  dfculbert@ifas.ufl.edu

October 18,  2007

Quick Links:  Identification   Habits    Bites   Prevention   Pesticides  Spider Survey!   References

 Feature Article - for release the week of  October 21, 2007 

Dan Culbert – Okeechobee Extension Horticulture Agent

 

 From Crawley to Creepy  

I had really intended to get off these recent articles about worms in trees and on grass.  But the folks in this community keep bringing in all kinds of creatures to identify.  Everybody wants to find out “how to destroy this bug”.  So bear with me for another week while I offer some background on another occasional visitor to our Florida Yards.

And just in time for Halloween, a specimen bag with three small spiders appeared last week for us to identify.  The visitor said she had “hundreds of them” all over the outside of their new trailer.  She also suspected that they snuck into a pet’s cage and bit one of her pets. 

An examination of these creepy creatures showed a small orange dot on the bottom side of the darkest brown spider.   A closer look with a magnifying glass showed its characteristic “hour-glass” shape, and confirmed its identity – the BROWN widow spider.

 

Widows and Buttons

Newcomers to Florida are sometimes shocked to learn that we don’t just have Black Widow spiders, but two kinds of Black widows, plus a Red widow and the Brown Widow.  Our UF Venomous spider picture bulletin also includes the Brown Recluse.  (But have no fear, despite many reports to the contrary, the Brown Recluse does not live in Florida.)

The one most likely to be encountered by people is the Brown Widow, Latrodectus geometricus. “Button spiders” are another common name for this group of arachnids – this comes from the small rounded body shape.  Brown widows were found most often south of Daytona Beach and along the coast, but the reports seem to be increasing into other areas and states.  There is debate if this spider is truly a native, or if it came here from other tropical areas. 

Brown widows are not that big – about an inch long when their legs are extended. The legs have darker bands at their joints.  The back of this spider can be colored from light gray to light brown to black, with various black, white, red and yellow markings.  I found a good reference that shows many possible colors, and they appear differently as they get older. [Want to see a "pet" Brown Widow?]  But the characteristic feature is seen on the underside of the abdomen:  an orange or yellow colored hourglass.  

The female widow lays about 250 eggs in a rounded egg sac that is about ¼ inch in diameter. The egg sac can confirm the identity of the Brown widow: the outer shape reminds me of a floating submarine mine or a sandspur.  Eggs hatch in about 20 days.  

Once a spider is found, it may signal a widespread population which may be hard to eradicate. Brown widows make their webs around buildings in well-lighted areas.  As the young spiders mature, they construct a loosely woven web – this cob-webbing also helps identify this as a widow spider.  In Florida, all the widows (except the northern black widow) breed year-round, and one female can produce up to 18 egg sacs.

 

A Bite to Remember

The widow spiders are extremely timid – they are not going to rear up and attack people.  They only human bites reported occurred when a spider was accidentally trapped between clothes and the victim's body.  And there is little chance that a pet would get bit, unless there is a lot of debris around the cage - that’s what attracts insects that are the food for spiders.

I’ve never been bit by a brown widow, so what is reported here is based on reliable accounts from those who have lived to tell about it. This includes all 2,500 people reportedly bitten by Widow Spiders across the globe since 1983; all survived - except two poor souls in Europe that had other health issues.

The bite of widow spiders usually feels like a pin prick. The initial pain disappears rapidly, leaving local swelling and two tiny red marks. The venom is a neurotoxin that comes from the bite.  It produces muscular cramps in the shoulder, thigh and back within 15 minutes to three hours.  In severe cases, pain spreads to the abdomen, blood pressure rises; nausea, sweating and difficulty in breathing also are symptoms.  Death can result, depending on the victim's physical condition, age and location of bite.  

In case of a widow bite, a physician needs to be consulted and prompt treatment is needed.  If possible, capture the spider for positive identification.  Proper treatment may depend on identifying the species.  Even the squashed remains of the spider can be useful for identification purposes.

Putting Widows to Rest

All this talk about this brown button spider may be of interest to Spiderman, bug lovers and Halloween celebrants, but what the average Jane and Joe wants to know is how do I protect myself and get rid of these things?

The best way to prevent spider bites is to avoid getting bitten.  The number one rule is: don’t put your hands in areas that you have not first inspected with your eyes. Wear gloves and a long-sleeved shirt when working areas that are likely to have widow spiders.

Since typical hiding places are in protected sites around homes, the best defense is to make your Florida Yard unfriendly for widows.  If you are around schools, UF has a fact sheet with specific suggestions for dealing with widows in that setting.

*       Sanitation is the most important control strategy – reduce clutter, move stored materials like firewood away from house.  

*       Routinely clean and vacuum up any suspected webs.  (Be sure to dispose of the dust bag into a sealed plastic bag when you are done!)  

*       Blasting webs and egg cases with a strong stream of water may remove them form walls, but aim the water steam at an angle to avoid getting hit by the water - and dislodged spiders.

*       Widows rarely come indoors, but make sure by tightly  fitting screens and windows .

*       Turn off lights at night to avoid attracting insects - the food source for these nocturnal spiders. 

Smashing them to smithereens also comes to mind, but if you miss, the potential for a bite is real.  So what about pesticide sprays?  Our Spider bulletin contains recommendations for both homeowners and commercial applicator pesticides.   The products also differ based on where they are going to be used.   Spraying around the perimeter of a building will not work.  Surprisingly, dusts applied to webs work well, but the applicator can easily get poisoned or bit.  Please check with our office to be sure that you are using the right product.  And as always - Read and follow all directions: The Label is the Law!

I’ve placed more information on our Okeechobee web page, http://okeechobee.ifas.ufl.edu.  If you need additional information on brown widow spiders, please email us at okeechobee@ifas.ufl.edu or call us at 863-763-6469.  Local residents can stop by our office at 458 Hwy 98 North in Okeechobee, and visit our Okeechobee County Master Gardeners from 1 to 3 PM on Tuesday afternoons.  GO GATORS!

Trade names, where used, are given for the purpose of providing specific information. They do not constitute an endorsement or guarantee of products named, nor does it imply criticism of products not named. The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin.  Florida Cooperative Extension Service / IFAS / University of Florida.  Larry A.  Arrington, Dean. Last update: 10/18/2007.  This page is maintained by Dan Culbert    

References

Bush, Sean P.  Widow Spider Envenomations.  Loma Linda, CA:  Loma Linda University Medical Center,  9/22/06. http://www.emedicine.com/EMERG/topic546.htm

Brammer, Angela.   “A little knowledge can help prevent spider bites.”  Gainesville: UF/IFAS Florida Cooperative Extension Service, School IPM website, Undated. http://schoolipm.ifas.ufl.edu/doc/spider_knowledge2_3.htm

Culbert, Daniel F.  “Not all Widows are Black”.  Vero Beach: Press Journal, 7/30/1995. http://okeechobee.ifas.ufl.edu/News%20columns/Brown.Widows.htm

Earp, Emily and Hillman, Josh  Latrodectus geometricus Brown Widow  [Pictures of Brown widows in Florida]. Florida Nature.org website, 2007.  http://www.flnature.org/species.asp?species=Latrodectus_geometricus

Koehler P. G.  Spiders [ENY-201].  Gainesville: UF/IFAS Florida Cooperative Extension Service, 9/2003.   http://edis.ifas.ufl.edu/MG206

Santana, Fred.  Brown Widow Spiders.  Sarasota: Sarasota County Extension Service, 2007. http://sarasota.extension.ufl.edu/IPM/BrownWidow.htm

Short, D.E. and Castner, J.L.   Venomous Spiders in Florida (SP-104).  Gainesville: UF/IFAS Florida Cooperative Extension Service,  2/1997. http://edis.ifas.ufl.edu/IN011

Shukla, Shantanu and Gour  Broome, Vivek. “First report of the brown widow spider, Latrodectus geometricus C. L. Koch (Araneae: Theridiidae) from India.”  Bangalore, India: Current Science, Vol. 93, NO. 6, 9/25/07. http://www.ias.ac.in/currsci/sep252007/775.pdf