Spider Bite Smarts

By Dr. Stuart Mitchell

Within the anterior cephalothorax of the spider, venom is produced by glands and delivered through fangs. Fangs are the piercing parts of jaws and deliver venom via small openings at the tips.

Bite or Sting?

There is sometimes confusion between a bite and a sting. Incorrectly, the terms are sometimes used interchangeably.

Bite

• Offensive (typically).
• Venom injected via structures of the mouth (fangs).
• May result in tissue destruction, allergic reaction, paralysis, and/or death.

Sting

• Defensive (typically).
• Venom injected via tapered, posterior structure (modified ovipositor or “stinger”).
• Immediate pain (usually non-fatal); an allergic reaction possible.

Venom composition, potency, and toxicity vary by spider species. For example, hunting spiders have more potent venoms than web-spinning spiders (except for Widow spiders (Latrodectus spp.). Only a few spider species can cause injury.

• Most spiders do not have enough venom.
• Most toxins are not harmful to humans.
• Fangs cannot penetrate human skin.
• It is doubtful that there are any truly “deadly” spiders (bites that can be anticipated to cause deaths in humans).

Venoms

• Envenomation of toxic spider compounds may cause skin lesions, systemic illness, neurotoxicity, and potentially death.
• Venoms are composed of complex proteins and proteolytic enzymes designed to incapacitate and/or initiate digestion of prey.
• Tarantulas have venom, but barbed, urticating hairs can irritate eyes, skin, and mucous membranes.

Two main clinical syndromes

Bite from a Black Widow spider (Latrodectism)

• Sharp pain at bite site.
• Spider often seen.
• Severe muscular contractions of large muscles.
• SLUDGE (salivation, lacrimation or eyes watering, urination, defecation, GI distress, vomiting, and bronchorrhea or excessive mucus).
• Hypertension, tachycardia, fasciculations (twitching), fever, and diaphoresis (sweating).
• Usually symptom resolution.
• Death is rare.

Bite from a Brown Recluse spider (Loxoscelism)

• Local bite often not noticed or stinging sensation.
• Spider rarely seen.
• Severe pain and itching.
• Possible clear or hemorrhagic vesicle to dark eschar.
• Eschar sloughs and can have progressive necrosis.
• In extreme cases, hemolytic anemia or red blood cell destruction, rash, arthalgias (joint pain), fever/chills, nausea/vomiting, and renal failure.
• Death is rare.

Take the bite out of spiders by taking the spiders out!

• A sticky situation. Glue traps are an easy, inexpensive way to monitor and identify spider activity.
• Hide and seek. Inspect attics, crawlspaces, basements, garages and storage areas.
• Keep it clean. Clear away spider webbing to differentiate future spider activity.
• Hunger strike. Reduce food sources by regularly treating perimeter areas for target insects.
• Professionally apply. Use professional products for environmentally friendly and strategic applications to reduce and eliminate spider pressures.
• Pyrethroid-based and pyrethroid-like products (including concentrate and aerosol formulations) are commonly used in the control of spiders. These products are often used for crack and crevice or spot treatments. Apply to areas where spiders crawl and hide, especially hidden surfaces around sinks, baseboards, doors and windows, refrigerators, cabinets, and stoves-be sure to consult the product label.
• Natural and botanical products can be complementary to spider control protocols. They are available in multiple formulations, including concentrates, aerosols, granules, and dusts. Dusts provide the benefit of clinging to spider webs. Dusts can be effective for use within wall voids, under insulation, behind electrical switch plates, and around light fixtures. Natural products may be helpful near bodies of water, such as boat docks, common spider harborage sites.

Professional product labels provide critical information about how to safely handle and effectively use pesticide products. Always read, understand, and follow product label directions.