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Venomous Spiders

RSSI Safety Minute

https://northwesternrssi.wixsite.com/rssi

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Identifying Venomous Spiders

  • You, or others in your lab might work with venomous spiders for your research (esp. in the biomaterials scope)
  • There are no venomous spiders native to northern Illinois, so most spiders you see are harmless to humans

Black Widows (Latrodectus mactans, hesperus, & variolus)

Brown or black spider with large, round abdomen. Characterized by the red hourglass on the ventral abdomen; occasional red, yellow, and orange dorsal and caudal abdomen markings. Produces cobwebs near the ground (usually below waist height) in undisturbed places, and often hangs upside down in their webs. Produces neurotoxic venom (α-latrotoxin)

Brown Recluse (Loxosceles reclusa)

A large pale tan to brown spider. Has violin-shaped marking on the back of their head, but characterized by 3 pairs of eyes arranged in a horizontal arc. Usually hides in debris and objects, emerging at night to hunt. They can run quickly and will only bite when trapped and pressed against the skin (e.g. in clothes). Produces necrotic venom (sphingomyelinase D)

Black Widow photo credit: Christopher Sharpe. The rest: https://en.wikipedia.org/wiki/List_of_medically_significant_spider_bites, https://en.wikipedia.org/wiki/Latrodectus, https://en.wikipedia.org/wiki/Brown_recluse_spider, �https://en.wikipedia.org/wiki/Phoneutria, https://en.wikipedia.org/wiki/Australian_funnel-web_spider

Non-N. American Very Venomous Spiders

Brazillian Wandering Spider (Phoneutria nigriventer)

Very large (5-7”), very venomous, accidentally shipped with bananas

Australian Funnel Web Spider�(Atrax robustus & others)

0.5-3”, aggressive, and wander�Has the most potent spider venom

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Handling Spiders

  • Don’t handle a spider if you do not need to do so. ESPECIALLY if you think it may be venomous.
  • If you plan to kill it, use a spray (e.g. RAID)
  • Do not stand UNDERNEATH the spider when you spray it (because it will fall on you)
  • If you do need to capture and move a spider, the cup-and-sheet method
  • Works well for smaller ones (e.g. all N. American venomous species), and can be modified for larger species.

https://www.wikihow.com/Catch-a-Spider, https://wildspotter.org/

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If it is an invasive species, keep the live/dead spider and report it to the USDA Forest Service using the Wild Spotter app

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Most spider bites are “dry” (no venom injected) or from species that do not harm humans.

However, more significant symptoms can occur:

  • Local: itching, rash, pain, reddening/purpling, blister, muscle pain/cramping
  • Systemic: sweating, difficulty breathing, headache, nausea, vomiting, fever, chills

In all serious cases (when symptoms exceed minor swelling and redness), the CDC recommends that you:

  • Stay calm and don’t try to remove the venom (it won’t work - dilution is the solution)
  • Identify and capture the spider if it is possible to do so safely.
  • Wash the bite area with soap and water. Alcohol disinfectant works if water is unavailable.
  • Apply a cool cloth/cold compress to reduce swelling
  • Elevate the bite area
  • Seek professional medical attention. If known, tell them what kind of spider inflicted the bite.

https://www.cdc.gov/niosh/topics/spiders/symptoms.html

Spider Bite First Aid