Printable brochure on Brown Widows

Brown Widow

Latrodectus geometricus

INTRODUCTION

L. geometricus or brown widow is slightly smaller and usually a lighter color then the famous black widow – Their color can range from tan to a very dark, almost black shade.  The brown widow shares the prominent “hourglass” markings on its underbelly similar to the black widow. However, this “hourglass” marking is either yellow or bright orange on the brown widow spider. Although the bite of a widow spider is feared, they are normally very timid, and will withdraw when disturbed.  Bites typically occur accidentally.  The venom of the brown widow is twice as potent as a black widow however, less venom is injected per bite.  

IDENTIFICATION

Because the brown widows markings have a wide range, from light tan to dark brown or almost black, with variable markings of black, white, yellow, orange, or brown on the back of their abdomens, they are not as easy to recognize.  The underside of the abdomen, if you can see it, contains the characteristic hourglass marking.  Another way to identify a brown widow is by the egg sac.  Other widow sacs have a tan to white smooth surface.  The brown widow’s egg sac is covered with pointed projections (spike like appearance) and takes approximately 20 days to hatch.

HABITAT
The brown widow is less selective than black widows and will construct shelters from webbing when structures are unavailable. The brown widow builds its web in secluded, protected sites around homes.  It has a fondness for buildings but will construct its web in all kinds of man-made structures, and even in vegetation. Some typical sites include inside old tires, empty containers such as buckets, nursery pots, mail boxes, entry way corners, under eaves, stacked equipment, cluttered storage closets, garages,  recessed hand grips of plastic garbage cans, undercarriages of motor homes, underneath outside chairs, & branches of shrubs

PREVENTIVE CONTROL
Sanitation is the key strategy in reducing infestations around the home.  The best way to eliminate and discourage the return of widow spiders is by routine cleanings. Always wear gloves if you suspect widows spiders to be present. Clutter reduction is less appealing to spiders. A thorough cleaning with a vacuum is an effective way to remove spiders, their egg sacs, and webbing.  After vacuuming, the vacuum bag should be removed and put in a sealed plastic bag for disposal.  This should be followed by regular inspections to insure that spiders have not returned.  Outside the home, potential hiding places such as building materials, firewood, and other debris lying on the ground should be moved away from the building or disposed of.  Any holes, cracks, or spaces around windows and doors should be sealed or fitted with weather stripping.

INSECTICIDAL CONTROL
If a spider problem still exists after sanitation then insecticides may  be used.  When a vacuum cleaner is not available direct contact with a non-residual aerosol spray will remove live spiders.  Spot treatment applications of a residual insecticide to locations where spiders build their web sites can be helpful in preventing new spiders from becoming established.  Although, reduction of outdoor harborage and sealing up cracks and holes is the best approach in spider prevention insecticidal dust followed by sealing cracks, will reinforce exclusion. When it is not feasible to vacuum, such as outdoors, an insecticidal dust can be very effective.  Dust can cling to webs for long periods of time so when the spider reportedly chews it’s web, to recycle silk, they consume the toxicant and die.  In places where there are multiple spiders a spot treatment of a residual insecticide to small areas can be effective.  Perimeter sprays around the foundation of a home may provide some relief but rapidly degrade in sunlight & may expose pesticides to non-target organisms.

Printable brochure on Brown Widows