Wednesday, July 4, 2012

The Brown Widow Spider ?

Lactodectus Geometricus, the brown widow)  It DOES have the characteristic red hourglass on the inner aspect of its abdomen.

     First discovered in the US within Florida, in 1935 the brown widow spider, lactrodectus geometricus
  is claiming new areas as habitat. The brown widow spider, has been making significant inroads in the habitats of black widow spiders. Generally, the brown widow has a less toxic bite than the black widow, but because brown widow spiders are less easily seen in campsites, outdoor areas, dog houses, sheds,greenhouses, trashcans, garages,  under picnic tables etc., bites are likely to be higher in incidence. The most recent study, which will be released in The Journal of Medical Entomology shortly, indicates that the brown widow is displacing habitat from the black widow.   The study presently applies to Southern California, however, it is a reasonable assumption that brown widows will be located soon, in other hot states, such as the Southwest and the American South soon, especially since significant progress in terms of habitat takeover have been made by these spiders in a very short time.

        This spider is suspected by entomologists to have evolved in Africa. It presently is known to definitively occupy Hawaii, California, Texas, Georgia, Louisiana and Mississippi, and South Carolina.   These are also found in Australia, Caribbean Islands, Japan, Cyprus and South Africa.  This is a prolific spider. It is reasonable to believe that it will continue to spread in warm climates, so keep an eye on its spread to your area too, in the coming years.  This spider likes woody vegetation.

       From a medical standpoint, although the brown widow bite is felt to be a less dangerous bite than a black widow, it is still the bite of a lactrodectus species.  It is still possible for human beings to react in a severe manner or anaphylactic or severe allergic manner,  to such a bite, which could require hospital care.  At least one person in the US has required hospitalization and advanced care following the bite of a brown widow. At least one reference, I have listed below, expressed that their experience with the brown widow is that the venom is MORE toxic than the venom of black widows.  (This is not corroborated by Univ. of California, at Riverside)  It is possible that there is subgroups variability in the California varieties and those found in Florida or Louisiana for example.

        It is recommended that we store rarely used items in sealed freezer bags to avoid the eggs and spiders of these and other species, from invading our items.

Research on this newer invasive species is ongoing.

References for this blog post:

Members of the media who would like the full report should write to or call 301-731-4535, ext. 3009.

The Journal of Medical Entomology is published by the Entomological Society of America, the largest organization in the world serving the professional and scientific needs of entomologists and people in related disciplines. Founded in 1889, ESA today has more than 6,000 members affiliated with educational institutions, health agencies, private industry, and government.

 For more information, visit
Richard Vetter
University of California, Riverside

 (They are collecting and researching these spiders)


city said...

nice posting.. thanks for sharing.

city said...

.thanks for sharing