Spiders

Spiders are feared or disliked by most, but they are beneficial for their role as predators of insects and other arthropods, and most are harmless to us.  Spiders are arachnids, not insects.  Many people confuse insects with spiders, spiders have eight legs and two body parts (a head region, and an abdomen).  They lack the wings and antennae that insects have.  Most spiders have toxic venom, which they use to kill their prey.  Most are harmless, or not toxic enough to cause a serious reaction in humans.  So only spiders with venom that causes a serious reaction in humans are called "poisonous" spiders.  There are a couple spiders that can be harmful to humans, they would be the Black Widow Spider, and the Recluse Spider.

The Black Widow spider (Latrodectus hesperus)

is the most common harmful spider in California.  The venom from its bite can cause reactions ranging from mild to painful and serious, but death is not likely.  If medical treatment is obtained, many symptoms can be alleviated.  Anyone bitten by this spider should remain calm and seek medical attention immediately, it's also helpful if the spider can be caught and saved for identification.  The adult female black widow has a shiny black body, with slender black legs and a reddish hourglass on the underside of the large abdomen.  The adult male Black Widow is about one half to two-thirds the length of the female, has a small abdomen and is seldom noticed.  The male has venom as well, but its fangs are too small to break human skin.  The Black Widow has an irregular web that is very tough-stranded.  The egg sacs are mostly spherical, about 1/2 inch long and 5/8 inch in diameter, creamy yellow to light tan in color.  A female may produce several egg sacs, the tiny young Black Widows which are nearly white in color, disperse to new locations by ballooning and infest new areas.  The Black Widow are generally found in dark, dry, sheltered, relatively undisturbed places such as among piles of wood, rubbish, or stones.  They also are found in garages, sheds, utility meter boxes, and crawl spaces.  People are most likely to be bitten when they disturb the spider while they are cleaning out or picking up items in such places.  Wearing long sleeve shirts and gloves could help to avoid any bites when working in these types of areas.  The symptoms of the Black Widow bite are largely internal.  Pain tends to spread from the bite to other parts of the body and muscular spasms may develop.  Other effects are fever, increased blood pressure, difficulty breathing, restlessness, nausea, and sweating.  The symptoms reach a maximum at about a day, and they subside of the next 2 to 3 days.  The Black Widow Spider is fairly common in California. 

The well known Brown Recluse spider

does not occur in California.  It has been brought to California in transport, and furnishings, but does not reside in the state.  The recluse spiders have a violin-shaped mark on the top side of the head region, but the mark is not always distinct.  The recluse spiders make large, irregular cobweb type webs that extend in all directions.  If a human is bitten by the recluse spider, the symptoms may not occur for several hours after the bite.  There may be flu like symptoms, along with the swelling, and redness around the bite location.  Bites from the Brown Recluse Spider have never been confirmed in California.