Educating Iowa Residents About Brown Recluse Spiders

Ken Holscher, Faculty, Department of Entomology


Brown recluse spiders are a potential public health pest due to the chronic effects that may result from their cytotoxic venom.  While not fatal, the effects that may result from a brown recluse spider bite include skin ulceration, tissue destruction, and permanent disfiguration that may require surgical repair.  Brown recluse spiders have been documented from Iowa dating back to at least 1968.  However, Iowa is at the extreme northern edge of the brown recluses distribution range.  As a result, infestations are sporadic, infrequent, and unpredictable.

Due to the rising media concerns and fears regarding brown recluse spiders, Iowa residents continue to seek unbiased information from ISU Extension.  These residents include private individuals seeking advice on spider identification and on how to best protect themselves and their families if a brown recluse infestation is found within their home, and professional pest control operators and public health officials seeking recommendations for effective spider control.


To provide prompt, reliable, and unbiased information to help educate Iowa residents, professional pest control operators, and public health officials about the identification, behavior, biology, and effective control of brown recluse spiders in an effort to reduce or minimize potential public health concerns or unwarranted treatment control costs.


A total of 72 spider specimens were submitted to my office for positive identification.  These specimens were submitted by private residents through their local ISU Extension Office, through the U.S. mail service, or through personal walk-in delivery.  Of these 72 spider specimens, only 4 were positively identified as brown recluse spiders with the remainder being harmless species of importance only as a nuisance.  Information on brown recluse spiders was also presented at 6 meetings or workshops, including a video satellite program broadcast statewide.  These meetings and programs reached over 1,200 Iowa residents and were designed for professional pest control operators, public health officials, and the general public.  In addition to group meetings, over 150 Iowa residents contacted my office through phone or written correspondence seeking information on brown recluse spiders or spider management.  Finally, 1 television interview, 5 radio interviews, and 4 newsprint articles were developed for local or statewide distribution and were viewed, heard, or read by hundreds of additional Iowa residents.


It is impossible to measure the impacts these educational efforts have had in reducing the fears and concerns regarding brown recluse spiders among Iowa residents.  On one hand, the 4 residents who did have a positive infestation confirmed within their home could take measures to protect their families and to implement effective control and eradication programs.  On the other hand, the remaining residents who were informed that they did not have an active infestation not only had their fears and concerns alleviated but potentially realized an economic savings of thousands of dollars in unwarranted control costs.

142 Integrated Pest and Crop Management

Page last updated: December 5, 2006
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