By Penny Pawl, UC Master Gardener of Napa County
Although the nursery rhyme tells us that Little Miss Muffet was frightened by them, spiders are in fact beneficial insects.
Scientifically speaking, spiders are Arachnids, invertebrates with two body segments, eight legs, no wings or antennae and no ability to chew.
I have several daddy long legs living in my house right now. We coexist well. They make large, messy webs on my ceilings. As soon as I clean up their webs, the spiders go right back to work. They make their webs in my garage also. I seldom find them outside.
The world of spiders is a big one. There are thousands of different types in California. Among the most common are tarantulas, grass spiders, Calisoga [sic] spiders, daddy long legs, sow-bug killers, American house spiders, black widow spiders, wolf spiders, garden spiders, and jumping spiders.
Occasionally you hear of someone getting bitten by a brown recluse spider, but those spiders are not established in California. When people move around the country, they can unknowingly bring them into California on household items.
About 20 years ago, I was bitten on the wrist by a spider found in linens that had recently arrived from another state. The bite was very painful, and the spider looked suspiciously like a brown recluse, but I squashed it so could not get it identified. If you get bitten by a spider and think it might be a brown recluse, seek immediate medical attention as the flesh around the bite slowly rots away.
Among all these spiders, we seem to hear the most about black widows. They will bite and their bite is poisonous. A black widow lived for a few years in a corner of one of my worm bins. We showed respect for each other and she never attacked me. When I worked in the bin, she moved to the corner and I avoided her.
The house spiders in my home are mostly daddy long legs; they are also called cellar spiders. They are easily distinguished by their exceptionally long legs, as compared to the size of their body. They belong to the Pholcidae family, which has about 80 genera and 1000 species.
A day or two ago I noticed a tiny thin web in my kitchen window. I searched around the window and, yes, the daddy long legs was back. Sometimes I wonder if it ever leaves. I have vacuumed the web up but somehow the spider survives.
According to what I have read, these creatures love to live with humans. And they like areas where there is some dampness. They do possess some venom, but their little fangs are not long enough to pierce human skin.
Rather than bite their prey they roll the prey up in their web. If you look at the web, you will see little bundles stored here and there. They have the messiest webs of all spiders. Unlike the neat webs so many spiders spin, these are just pieces of silk going every which way. The spiders usually hang upside down in their web, just waiting for something to become entangled. This habit, along with their legs, makes them easy to identify.
On occasion, and as recommended by the UC Davis Integrated Pest Management (IPM), I have moved other types of spiders outside. Most spiders are great at pest management. It is estimated that spiders eat 800 million tons of bugs a year. Most of their prey are flying insects, although at times they will target non-flying insects.
While researching this article, I learned that Pholcids feed on house spiders and keep flies in check, so your house will be cleaner if you leave them in peace. If you see a spider, you don't need to remove it. Just remove the messy web on occasion.
The UC Master Gardeners of Napa County are volunteers who provide University of California research-based information on home gardening. To find out more about home gardening or upcoming programs, visit the Master Gardener website (napamg.ucanr.edu). Our office is temporarily closed but we are answering questions remotely and by email. Send your gardening questions to mastergardeners@countyofnapa.org or leave a phone message at 707-253-4143 and a Master Gardener will respond shortly.
UC IPM has this Pest Note on spiders, with identification guidelines, and management advice.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn7442.html
By Michelle Ramsey, Butte County Master Gardener, August 23, 2013
The scary-looking, ominously-named wolf spider is actually a beneficial insect. Wolf spiders belong to the class Arachnida andare members of the family Lycosidae (derived from the Greek word lycos, meaning wolf). Wolf spiders stalk their prey like wolves do; they do not spin webs or use silk to subdue prey. They are fast-moving, aggressive ground predators with excellent eye sight (helped in no small part by the fact that they have eight eyes, arranged in three rows: the first row has 3 small eyes, the second has 2 large eyes and the third row, closest to the top of the head, has 2 medium-sized eyes). They are nocturnal and hunt for insects mainly at night. They are likely to be found on the ground in open areas like farm fields and grassy environments, or harboring in ground tunnels, amidst pieces of firewood or debris. There are more than 2000 wolf spider species, with body sizes ranging from less than one millimeter to 30 millimeters (.04 to 1.2 inches).
Wolf spiders provide natural control of harmful insects. The Carolina Wolf Spider (Hogna carolinensis) is the largest of the wolf spiders. It is brown with black markings. Its body can measure more than one-inch long (and the whole spider can measure 4 inches across, from legs to legs). Female wolf spiders are larger than males; their undersides are solid black. Because some wolf spiders are large and hairy, they are sometimes mistaken for tarantulas.
Wolf spiders are not known to be aggressive but will bite if provoked or threatened. Their bite is not considered dangerous to people but it can be painful (like a bee sting). When disturbed, they will retreat very quickly.
Young wolf spiders hatch from eggs and look like tiny adults. They shed their skin as they grow. Males reach maturity from spring to summer. Mating occurs in autumn and the males die before the winter begins. Females lay eggs soon after mating. They carry their egg sacs in a silk cocoon attached to their abdomen by spinnerets. The spiderlings hatch in June and July and attain only half of their full size by the following winter. After hatching, the spiderlings cling to the mother’s body for about a week before detaching. They too will overwinter and complete their growth the following spring and summer. Female wolf spiders may live for several years. It is common to find females carrying their young spiderlings on their backs during the summer months. They can be a common pest in the fall when they begin to seek shelter from cooling temperatures.
The wolf spider is a solitary creature, preferring to live and hunt alone. Most are wanderers without a permanent home; however some Carolina wolf spiders create deep tubular burrows to live in. While wolf spiders prefer to live outdoors on the ground, they may occasionally wander indoors, where they might be found around doors and windows, and in garages. They may be seen running across the floor when disturbed. To keep spiders out of your home, seal cracks, gaps and other openings. For immediate and long-term control of wolf spiders, physical removal and/or destruction of the individual spider may be the best control.
For further information visit: http://www.ipm.ucdavis.edu/QT/commongardenspiderscard.html