Newly hatched black widows are white with black spots on their abdomens with a cream colored hourglass. Later as they mature they become cream and brown-striped. The black widow requires about 4 months from egg to maturity with the females going through six to nine molts. Over their one to two year life span the females produce several egg sacs, each containing several hundred eggs. Female black widows guard the sac, which resembles a silken cocoon, until the eggs hatch. During this time she is most likely to bite when threatened. Eggs are most frequently encountered from May to October.
All stages of both sexes are venomous. Even the egg sacs contain poison.
The female black widow spins a silken web usually in protected places such as under stones, house steps, decks, etc. The webs are irregularly shaped with strands running in many directions. They are said to appear "messy". The spiders hide during the day, and hang upside down in their webs at night.
The black widow venom is a nerve toxin. The initial bite may feel like a pin prick. Although bites are generally not fatal, they should be considered dangerous. Contact your local poison control center immediately. If possible, capture the spider for identification.
NOTE: Black widows are beneficial predators feeding on roaches, crickets and other pests.
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Last Updated May 18, 2011
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