- Author: Help Desk Team
This time of year, as the heat increases and things start to get dusty, you might see a number of webs on your plants. Uh oh. Are these webs a sign of spider mites?
Chances are the webs you see covering the ends of branches are actually created by spiders, a close relative to spider mites, and are nothing to worry about. Spiders are predators of insects, some of which are pests, and the webs are used for capturing prey. According to the UC Cooperative Extension, there are at least 54 families and over 1,000 species of spiders in California (https://ipm.ucanr.edu/natural-enemies/spiders/#gsc.tab=0).
Most spiders are beneficial to your garden. Think of them as a free pest control service and remember that among poisonous spiders only the widow spiders are commonly found in California, and these generally stay hidden in places like cellars or woodpiles. And even though the vast majority of spiders are harmless, that doesn't mean you want them surprising you in the garden! You can learn to recognize the many types of spiders hunting among your plants. Some of the more common web-spinning spiders you might see include:
• Dwarf Spiders: These tiny spiders hunt during the day and produce sheet-like or irregular crisscross webs on plant surfaces. You will find them in the plant canopy and in ground litter. They are common in fields and vegetable crops.
• Cobweb Spiders: Hang upside down in sticky, irregularly spun webs waiting for prey. Most are small and harmless, although widow spiders fall into this category.
• Funnel weavers include the Common House Spider: These spiders hang out in the garden, and on walls and ceilings in the house. They feed during the day and night, hiding and waiting for their prey near the ground in most types of vegetation. They spin funnel shaped webs, often with a flat extension covering the plant or soil. Their webs become conspicuous in morning light after collecting dew.
• Orb weavers or Garden Spiders: Often large and colorful, these spiders spin elaborate webs in concentric circles in the garden. They wait in their webs or nearby for prey to become entangled. Often, we can tell the species of the spider by the pattern woven into their web.
• Sac spiders: Typically nocturnal, Sac spiders live in silk tubes in places such as corners, beneath plants, or on bark, and stalk their prey at night. They occur both indoors and out.
Spiders that don't spin webs include the jumping spiders, lynx, crab and wolf spiders. Like their web-spinning cousins, these spiders are beneficial in your garden, preying on insects and other pests.
Are the webs damaging my plants?
In these photos you can see spider webs on a Daphne shrub, some succulents, and a Japanese Pieris. Notice there is no visible plant damage associated with the webs, although occasionally some dead leaves may get caught in a web, such as with the Japanese Pieris. A closer inspection shows the web hasn't caused the leaf damage — in this case it's sunburn from the recent heat wave.
Try to refrain from using insecticides as they aren't necessarily effective on the spiders, and you risk killing other beneficial insects. You can remove cobwebs from your plants by sweeping or hosing them away, or if inside, with a vacuum cleaner or mop. Instead, learn to recognize the spiders in your garden and you will come to appreciate the antics of the jumping spiders, or the beauty of a web with droplets of dew shining in the early morning.
• Quick Tips about spiders: https://ipm.ucanr.edu/QT/commongardenspiderscard.html
• Video to help you learn to identify spiders: https://www.youtube.com/watch?v=Bs-OUvY8L80.
• Identifying and managing spiders: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7442.html
Help Desk of the UC Master Gardeners of Contra Costa County (RDH)
- Author: Laura Fordyce
While many people fear spiders or dislike their cobwebs, most spiders are beneficial to have around – even in the home! Spiders are predators of many insect pests and rarely cause harm to people. The only medically significant spiders in California are brown and black widows. While these spiders have the potential to cause harm, it is rare that they will bite, even in areas where they are very common. Like most spiders, they prefer to stay hidden and avoid people.
Some common web-spinning spiders you might encounter outdoors include:
- Funnel weavers: feed during the day and night near the ground in most types of vegetation, including low-growing plants and trees. Spin funnel-shaped webs, often with several-inch-wide, flat extension covering plants or soil.
- Sac spiders: spin silken tubes or sacs under bark, among leaves, and in low plants or on the ground, where they hide during the day or retreat after hunting. They are typically nocturnal, medium-sized, pale spiders with few markings.
- Garden spiders: feed on insects that fly, fall or are blown into their webs. Elaborate silken webs are spun in concentric circles.
- Dwarf spiders: prey on insects that fall, walk or land in their webs. They are diurnal (day active) spiders found in the plant canopy and among litter on the ground. Dwarf spiders produce sheet-like webs on the surface of plants or soil.
- Comb-footed spiders: feed on insects that walk or fly into their webs. They almost always are found hanging upside down by their claws in irregularly spun, sticky webs, waiting for prey. Generally they have a soft, round, bulbous abdomen and slender legs without spines.
Unwanted cobwebs can be swept, mopped, hosed or vacuumed up. Insecticides should not usually be used against spiders outdoors and don't provide good control anyway.
For more information about spiders in and around the home, visit the Pest Notes: Spiders.
This story first appeared in the UC Integrated Pest Management Program's Pests in the Urban Landscape blog.
- Author: Lauren Fordyce
Are you noticing an abundance of cobwebs outside, on plants, fences, homes, or outdoor furniture?
While many people fear spiders or dislike their cobwebs, most spiders are beneficial to have around– even in the home! Spiders are predators of many insect pests and rarely cause harm to people. The only medically significant spiders in California are brown and black widows. While these spiders have the potential to cause harm, it is rare that they will bite, even in areas where they are very common. Like most spiders, they prefer to stay hidden and avoid people.
Some common web-spinning spiders you might encounter outdoors include:
- Funnel weavers: feed during the day and night near the ground in most types of vegetation, including low-growing plants and trees. Spin funnel-shaped webs, often with several-inch-wide, flat extension covering plants or soil.
- Sac spiders: spin silken tubes or sacs under bark, among leaves, and in low plants or on the ground, where they hide during the day or retreat after hunting. They are typically nocturnal, medium-sized, pale spiders with few markings.
- Garden spiders: feed on insects that fly, fall, or are blown into their web. Elaborate silken webs are spun in concentric circles.
- Dwarf spiders: prey on insects that fall, walk, or land in their web. They are diurnal (day active) spiders found in the plant canopy and among litter on the ground. Dwarf spiders produce sheetlike webs on the surface of plants or soil.
- Comb-footed spiders: feed on insects that walk or fly into their webs. They almost always are found hanging upside down by their claws in irregularly spun, sticky webs, waiting for prey. Generally they have a soft, round, bulbous abdomen and slender legs without spines.
Unwanted cobwebs can be swept, mopped, hosed, or vacuumed up. Insecticides should not usually be used against spiders outdoors and don't provide good control anyway.
For more information about spiders in and around the home, visit the Pest Notes: Spiders.
- Author: Kathy Keatley Garvey
(Note: The main UC Davis Department of Entomology news page is at https://entomology.ucdavis.edu.)
What's a picnic without bugs!
The UC Davis Department of Entomology and Nematology is gearing up for the 110th annual UC Davis Picnic Day, set April 20.
This year, all of the entomology exhibits, including those at the Bohart Museum of Entomology, will be at Briggs Hall. (The Bohart Museum headquarters in the Academic Surge Building will be closed on Picnic Day.)
Picnic Day at Briggs Hall is from 9 a.m. to 5 p.m. Some of the activities will closer earlier.
The list of events and activities in and around Briggs Hall will include:
Bug Doctor
Briggs Hall Entryway
Graduate students will answer questions about insects. What's that bug? Attendees are encouraged to bring an insect or photo for identification.
Cockroach Races
Front of Briggs Hall
American cockroaches, Periplaneta americana, from Bob Kimsey's forensic lab, race on a specially made track, while roach fans cheer for their favorites. (Sometimes the athletes are named for faculty, friends or bystanders.)
Medical Entomology
122 Briggs Hall
Carla-Cristina "CC" Melo Edwards of the Geoffrey Attardo lab is coordinating the medical entomology display. Her research focuses on investigating the physiological mechanisms underlying pyrethroid resistance in Aedes aegypti (the yellow fever mosquito).
Diversity of Arachnids
122 Briggs Hall
Doctoral student Emma Jochim of the Jason Bond lab is coordinating an exhibit she created last year to display the diversity of arachnids, such as vinegaroons, whip spiders, tarantulas, and scorpions. "We'll have live animals and fact sheets that will give a general overview of their diversity, behavior, and habitat," Jochim said. "I'll also bring some curated specimens to show what goes into creating a scientific collection and talk about why collections are important for understanding biodiversity. "
Maggot Art
Briggs Courtyard
Artists--children and adults alike--create maggot art by dipping a live maggot into water-based, non-toxic paint. It's suitable for framing (or at least a spot on the refrigerator door). This event will close at 3 p.m. this year (last year it was at 5 p.m.)
Dr. Death
122 Briggs Hall
Forensic entomologist Robert Kimsey will display and discuss his work in his "Dr. Death" booth. Last year Kimsey pin-mounted and identified flies from various cases and research efforts, and displayed studies on the sequence of development of individual maggots, calling attention to the development and sequence of communities of insect maggots. "By these means, approximations about how long a person has been dead can be made," he told the crowd.
Entomology at UC Davis
122 Briggs Hall
Displays of insects, including bees, ants and more. Graduate students, faculty and emeriti will staff the tables.
Bohart Museum of Entomology
Front of Briggs Hall
A pop-up tent, staffed by the Bohart Museum, will include stick insects (walking sticks) and Madagascar hissing cockroaches. "We are excited to be part of the bigger department's offerings," said Tabatha Yang, education and outreach coordinator. Give-aways are also planned.
Fly-Tying
Briggs Hall courtyard
Fly Fishers of Davis will show attendees how to tie a fly. The recipients take home the flies.
Insect-Themed T-Shirt Sales
Briggs Hall entryway
Members of the Entomology Graduate Student Association (EGSA), led by president Mia Lippey, will be selling their popular insect-themed t-shirts, including The Beetles. The T-shirt, EGSA's all-time best seller, is a take-off of the cover of The Beetles' Abbey Road alum. However, instead of the Beatles crossing the road in a single file, four beetles (family names Phengogidae, Curculionidae, Cerambycidae and Scarabaeidae) do so.
Mosquito Control Booth
Entrance to Briggs (below front steps)
Sacramento-Yolo Mosquito and Vector Control District will be providing information on mosquitoes, answering questions, and handing out give-a-ways, including mosquito repellent.
UC Statewide Integrated Pest Management (UC IPM)
Briggs Hall Courtyard
“We plan to have many of our usual materials on display and will be giving out the live lady beetles (aka ladybugs) again,” said urban and community IPM educator Lauren Fordyce. “We purchase them from a local garden center. In addition to that, we plan to have a prize wheel that adults and kids can spin, answer a question, and win a prize if they answer correctly. We may also have temporary insect tattoos to give away.”
Ranked Third in the Country. The UC Davis Department of Entomology and Nematology is ranked third among “The Best Entomology Colleges in the United States for 2024" by universities.com. The department includes 24 active and 19 retired faculty; 28 graduate students (five in the master's degree program and 23 in the doctoral degree program); 47 undergraduate entomology majors (based on the Office of Academic Support and Instructional Services (OASIS) Student Reports); and a staff comprised of 27 academics (non-faculty), 24 career, and 56 student assistants. Professor and chair of the department is molecular geneticist and physiologist Joanna Chiu.
With Halloween coming up I am seeing lots of scary faux spiders among front yard Halloween decorations. I must admit I am guilty of feeding into the arachnophobia that so many people have by placing a big fake hairy tarantula in my yard.
Fascinating Creatures
Most spiders are solitary creatures, but some form groups and even cooperate in brood care, caring for other spiders' offspring.
Not all spiders spin webs but those that do can create an incredible assortment of web designs, depending on the species, including spiral orbs, funnels, tubular, or ground sheets.
In some cases, two or more males will perform for a female to compete for her favor.
Some drop their silk to act as parachutes so they can drift on the slightest breeze
While spiders do not have brains in the traditional sense, a type of jumping spider appears to remember similar prey it has encountered, using trial and error to determine what works in capturing it.
Common and Beneficial
Spiders are the most common miniature living things living in our homes (besides micro-organisms). We are seldom aware of them because they conceal themselves in hidden spots (thus camouflaging themselves from their prey), tend to be active at night, and avoid humans. After all, we are much bigger than they are!
Spiders are beneficial organisms because they feed on common indoor pests such as mosquitoes, flies, roaches, earwigs, and moths. An additional benefit: many of the indoor pests that spiders consume can transmit diseases, i.e., mosquitoes, fleas, flies, and cockroaches. If left alone, spiders will consume most of the insects in your home, thus providing effective pest control.
Spider Bites
The jaws of most spiders are too small to bite humans. Of those that can bite, they will bite only if provoked, but very few spider bites are dangerous to humans. If you are bitten, the bite area may swell slightly and itch.
The adult female black widow is the primary spider in California capable of seriously injuring people. If bitten, remain calm and seek medical help.
Contrary to common myth, the brown recluse spider does not reside in California.
Managing Spiders
If you do have a spider issue around your home, the most effective way to manage them is to do regular housecleaning. Sweep or vacuum up their webs both indoors and outdoors, and prevent clutter build up that can provide hiding places for them both indoors and outdoors. If you do come across one, capture it in a jar and release it outside in an out-of-the-way spot. Avoid using pesticides since the chemicals will also kill other beneficial insects.
Appreciate Spiders Beneficial Role and Help Protect Them!
I will continue to put out my big “scary” tarantula out with the Halloween décor because spiders are so awesome. However, I do not put out the fake webbing, because like real spider webs, they can trap beneficial insects, spiders, and even small birds such as hummingbirds.
I will continue to allow spiders to share my home and garden, so they can do their crucial work of reducing pests. I much prefer having a few spiders around than mosquitoes, flies, moths, or cockroaches!
You do not have to love spiders like I do, but I hope you can appreciate the vital role arachnids play in our homes and gardens, and generally let them be.
References:
Spiders: https://ipm.ucanr.edu/QT/spiderscard.html
Pests of Homes, Structures, People and Pets: https://ipm.ucanr.edu/PMG/PESTNOTES/pn7442.html
Denise Godbout-Avant has been a UC Cooperative Extension Master Gardener since 2020.
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