Black Widow (genus Latrodectus) molting
Spiders are ubiquitous in Davis. Cellar spiders, aka Daddy Long Legs, are probably the most common and least harmful, though the Black Widow spiders have also been noted in the area. Brown recluse spiders are not found in Davis; people commonly misidentify brown colored spiders as Brown recluse spiders.
Some people think of spiders as pests, but the truth is that spiders feed on flies, mosquitoes, cockroaches, etc., thus keeping populations of many others pests in check.
Spiders are arthropods of the class Arachnida and the order Araneae. They are related to mites, ticks and scorpions, although they differ from them in that they have two body segments, all have poison glands in their chelicera, or jaws, and have a spinneret, or silk producing gland on their abdomen. Some types spin webs, some use their webs as bolas, some use their webs to create trap doors. Some spiders rarely use their webs at all. The largest group of spiders is the Salticidae, or the jumping spiders.
There are many, many different spiders to be found outside, from flower spiders, to jumping spiders, and even fairly large garden spiders, which can be over an inch long from tip of cephalothorax to end of abdomen.
Indoors, the most common spider is probably the Daddy Long Legs (not to be mistaken for the Harvestman arachnid) or Cellar spider, spiders of the family Pholcidae. They can also be identified with the cobwebby, hammock-like webs they commonly spin in houses. You probably have this spider in your apartment. Contrary to urban myth, these spiders are completely harmless to humans, whether alive or ground up into a powder. A possible domestic spider also includes the Black Widow Spider, a member of the genus Latrodectus. Unlike the aforementioned Cellar spider, the females pack a potent venom capable of harming an adult human, though it is not usually fatal. They are identified by their black or brown color, and large abdomen. Females also have the red hourglass on their underside which identifies them as widows. They commonly can inhabit sheds and other generally disused structures, and lay hanging sacs of eggs. Some places I have found widows include under the cement bike lock structures that are all over the campus, and the old shed near the Bee Biology building. Davis is full of black widows. I have several times found them under the lids of the recycling containers here. They're pretty shy, don't like light, and move relatively slowly. Davis is also home to wolf spiders and jumping spiders.
Spiders can be found almost anywhere where insects, their primary prey, can be found. In other words, almost anywhere. Spiderlings can use their silk to balloon long distances, and distribute themselves over a wide range.
These are all local species, but not all photos are of local spiders. If you see a good example of one, please snap a picture so we can see our local eight legged beasties.
I'm not sure this is true. Could someone with better knowledge remove non-local spiders below? It would be very helpful. —NumiaCairaguas
Davis is in the range for all the spiders listed below. Ask a professor?
Orb-weaver_spider (family Araneidae) Wolf Spider (family Lycosidae), deceased Pholcids (family Pholcidae) typically have a long-ish abdomen, and very long (and brittle) legs. If the webs are cobwebby, it's most likely a pholcid.
Jumping Spider (family Salticidae)
Maybe someone wants to classify these (taken in my yard):
Found this guy creeping on the carpet when I first moved into my apartment last fall — JournaL
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2007-03-27 12:53:45 My scout master back in the day made us totally fear the brown recluse. Those things will mess you up. If you don't die your flesh like turns to liquid. Nasty things! —BradBenedict
2007-03-27 15:18:17 Professor Kimsey (he teaches the zoology class, BIS 1B) told me that Brown Recluse Spiders don't live in California. I want to see references that say otherwise, or else that spider should be removed from this page. —NumiaCairaguas
I know multiple people who have been bitten by Brown Recluse in Ca Daubert
Kimsey was right. See http://en.wikipedia.org/wiki/Brown_recluse_spider#Distribution , or AlexMandel's link in the comment thrad below. It's a very, very common mistake, so I doubt they actually were "the" brown recluse spiders. -ES
2007-03-27 15:18:53 ...I forgot to say please. :-) —NumiaCairaguas
2007-03-27 15:21:32 I looked up info on BRs a while back because my wife thought she saw one... everything thing I found said they didn't exist in central CA (though some had been supposedly seen in southern CA, those references were really weak) —WesHardaker
I looked this up a while ago too, and had found that the natural range of Brown Recluse did not include much of California if any part (South Eastern near Arizona was the most likely). I did however here recently that they have been spotted in CA as invasive species brought in by accident in some places. It's unclear wether there is a self sustaining population anywhere in the state though. This UCR ANR page appears to have the most comprehensive and reliable information. —AlexMandel
2007-07-17 09:15:20 I snapped a shot of that black and white jumping spider. It thought it was really pretty, but it seems there is a better picture up here. Does anyone know if it has a common name? —CarlosOverstreet
2007-07-18 07:53:13 The wikipedia link under the picture, assuming you're talking about the same one I'm thinking of, says it's a "jumping spider". And if you don't like them the only place you can live is greenland... —WesHardaker
2013-02-09 11:59:12 Want to participate in a local Citizen Science Project? As of 2012 Explorit Science Center has been doing a Citizen Science Project concerning spider distribution in Yolo County. Anyone who takes photos anywhere in Yolo County is invited to participate and help build up the database. Participants are asked to register at http://www.explorit.org/csp/registration to get an ID number as an official participant and then sign up with Explorit's Where Is My Spider Project at iNaturalist.org at http://www.inaturalist.org/projects/where-is-my-spider. A pilot was run in 2012 and as of 2013 the project is starting over using iNaturalist. There are smart phone apps for recording observations on iNaturalist! —AnneHance