Black Widows

What do black widow spiders look like?  

  • While Florida is known to have Southern Black Widows, Northern Black Widows, Red Widows and Brown Widows, they are all easily identifiable with a glossy jet-black body and a bright red hourglass on the underside of their abdomen.  
  • They may also have red spots on the underside of the abdomen.
  • The size of the female body is: 1/2 inch while the male is: 1/4 inch.
  • Two major body regions: head and thorax formed into a cephalothorax; and bulbous abdomen.
  • Female widows are larger than their male counterparts. 

What are the habits of black widow spiders?

  • Black widow eggs are laid in silken sacs (which are protected by the female).
  • Females produce 6-21 sacs, each one containing 185-464 eggs.
  • Young spiderlings remain in the case for a short period and live in close proximity to the nest before producing long threads of silk that help them float away like kites.
  • Development time (egg to adult): approximately one year.
  • Life span of females: up to three years; life span of males: approximately 180 days.
  • Webs are built in dry, protected locations where prey is likely to travel, e.g., corners of exterior garage doors, in/around light fixtures, among stones and rocks, woodpiles, under decks, hollow stumps, rodent burrows, beneath benches, pool covers, etc…
  • Indoors they are found in basements, cellars, crawl spaces, garages, barns, outbuildings, sheds, meter boxes, brick veneer, pump houses, etc.
  • Webs are considered ugly and irregularly-shaped, approximately one foot in diameter, and used to trap prey, usually insects, long enough for the spiders to wrap them in more silk before giving them a lethal bite.

What is the danger of black widow spiders? 

  • Female black widows produce a potent neurotoxin in poison glands and bite if handled roughly, provoked or disturbed resulting in a bite that mimics a wasp sting.
  • While somewhat rare, several deaths occur annually that are attributed to black widow bites and subsequent anaphylactic reactions.  
  • Symptoms may begin between 1-3 hours after the bite and can include intense pain, nausea, sweats, vomiting or muscle cramps. 
  • Following the bite, venom moves through the lymphatic system via the bloodstream. 

How do I kill black widow spiders? 

  • Contact insecticides can be used to kill adult black widow spiders but may have minimal to no impact on eggs.  Thus, a vacuum should be used in order to remove spiders, webs, and egg sacs, and the bag should immediately be sealed and discarded in the trash.
  • A webster brush can be treated with a pyrethroid and brushed along the eaves of roofs, around gutters, soffits, fascia boards and other areas where black widows are likely to build webs.  
  • The underside of pool covers, low lying porches, low lying decks, etc… can be treated with pyrethroids on a preventive basis to deter web building. 
  • Outdoor lighting should be changed if it attracts insects to the structure as this is the source of black widow prey.

Keeping black widows away from your home or business is an ongoing process that your Innotech Pest Management entomologist-trained service technicians can manage for you.  Let us remove the risk of these dangerous spiders and help you maintain a pest-free home.