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Posts Tagged: IPM

Why mud daubers are on spider patrol

UC Cooperative Extension advisors are on the front line and get the most interesting questions from our community. Someone brought some wasps into our office, and was worried they were invading her home, and wondered how to get rid of them. They were identified by the UC Davis Entomology Museum as black and yellow solitary mud dauber wasps, which are natural predators of spiders, and hence beneficial! Before you reach for that can of insecticide or heaven forbid, a blow torch to control spiders, talk to a UCCE advisor or Master Gardener in your county and read this blog for more information on managing them.

Yellow and black mud dauber wasps are predators of spiders but harmless to people. Adults are about 1-inch in length with true wasp waists!

Here's all you need to know about mud daubers and spider control

That mud you track into your house is nothing compared to what mud daubers can do — and what they do to spiders. Female mud daubers, or wasps, build mud nests for their young — and provision them with spiders.

Where are the nests and what do they look like?  

Female mud daubers, the architects, build those characteristic rectangular mud nests in protected areas of our homes, shops and garages, such as along eaves, walls or ceilings. Mud daubers are black and yellow solitary wasps (Sceliphron caementarium) that hunt spiders for their young. Another wasp, the blue mud wasp, reuses the black and yellow mud dauber wasp nests and primarily preys on black widow spiders.

Mud dauber wasp nests with holes where adults have exited after completing their immature stages.

Do mud daubers sting or bite? 

Mud daubers do not aggressively protect their nests. Unlike hornets and other social wasps, they are generally docile and rarely sting. 

Are mud daubers dangerous?

No, mud daubers are harmless and actually beneficial. They prey on spiders, including black widows, a favorite prey. They pack each cell with up to 25 to 30 spiders for their young. With about 15 to 20 cells per nest, that's over 500 spiders eaten. This is good news, especially for those of us who fear black widow spiders. True, mud daubers can be a nuisance, as their mud nests look messy, but they are generally peaceful.

How do they make their nests?

Females construct their nests by gathering globs of mud in their mandibles (jaws) from a nearby source of wet dirt. They carry the mud to a protected nest site, where they construct a cell. Then they begin hunting for spiders to provision the cell for their young, and lay a single egg inside. When they capture a spider, they sting it, permanently paralyzing it. This preserves the spider until their larvae are ready to eat it. When the cell is full of spiders, the female mud dauber caps it with more mud and builds another cell next to it. After the egg hatches and the food gone, she pupates. When an adult emerges, it opens the cap, leaving holes behind in the nest for the next cycle.

Mud daubers have a low reproductive rate, with about 15 to 20 eggs per female. Adults are active during the day during spring and summer with multiple generations per year. Queens overwinter in the cells in the larval stage. Adults sip nectar from flowers, where the male mud daubers are often found. Mud dauber wasps have good vision and use landmarks to locate nests and hunt spiders. They prefer protected areas where there are plenty of spiders. Sometimes you might see them going in and out of your house vents, hunting for spiders in your basement or attic.

Mud dauber pupa (right) and cells packed with spiders, showing the importance of these wasps for providing natural spider control.

How do mud daubers avoid being eaten by spiders?

Some are able to land on webs without getting entangled, and pluck the web to simulate an insect in distress. When the spider rushes to capture its prey, it becomes a victim of the wasp's paralyzing sting. The wasp then carries it back to her mud nest.

How do you get rid of mud dauber nests?

Although mud daubers are considered beneficial, you can remove the nests by scraping them off with a paint scraper or a knife into a dust pan, and then tossing them or moving them somewhere else where you don't mind their activity. The best time to remove the nests is in the late evenings when wasps are not active, or during the wintertime when they are dormant.

Do I have to worry about getting stung by a wasp or bit by a spider during nest removal?

No, the spiders are paralyzed and the wasps are not aggressive. Mud daubers can sting, but only if directly handled or if they accidentally snag in your clothing.

What's the best way to get rid of spiders?

Overall, spiders are beneficial because they're predators and feed on pests like flies. Most spiders cannot harm people. Those that might injure people — for example, black widows — generally spend most of their time hidden under furniture or boxes, or in woodpiles, corners or crevices. The spiders that we commonly see out in the open during the day are not aggressive toward people. The brown recluse spider has occasionally been brought into California in household furnishings, and other items, but it does not reside here. Spiders enter houses and other structures through cracks and are also carried inside on plants, firewood and boxes. 

According to the UC IPM Spider Management Guidelines, the best approach for controlling spiders in and around your home is to remove hiding spots for secretive spiders such as black widows, and regularly brush or vacuum webs from windows, corners of rooms, storage areas, basements and other seldom used areas. This is effective because their soft bodies generally cannot survive this process. If you see a dust-covered web indoors, it's no doubt an old web that a spider is no longer using.

Why should one protect mud dauber nests?

Because mud daubers eat spiders, especially the cryptic black widows. In the process of cleaning spiders and webs, be sure to try protect those mud nests, because mud daubers naturally help control spiders in and around your home.

Blue mud wasp adults favor black widow spiders. Photo credit: University of Florida Extension.
Posted on Tuesday, December 4, 2018 at 8:05 PM
Tags: IPM (35), Rachael Long (1), spiders (2)
Focus Area Tags: Pest Management

2018 Kearney Alfalfa and Forage Field Day: Presentations now available

This year's Alfalfa and Forage Field Day held on September 19, 2018 at the Kearney Agricultural Research and Extension Center in Parlier, CA, was...

Posted on Thursday, October 25, 2018 at 1:10 PM
Tags: AgRIC (1), Alfalfa (7), Forage Crops (1), IPM (35)

Congratulations, Frank Zalom: Editor-in-Chief of Journal of Economic Entomology

Frank Zalom, distinguished professor of entomology at UC Davis (shown here in an almond orchard) is the newly selected editor-in-chief of the Journal of Economic Entomology. (Photo by Kathy Keatley Garvey)

Congratulations to integrated pest management specialist  Frank Zalom, distinguished professor of entomology at the University of California,...

Frank Zalom, distinguished professor of entomology at UC Davis (shown here in an almond orchard) is the newly selected editor-in-chief of the Journal of Economic Entomology. (Photo by Kathy Keatley Garvey)
Frank Zalom, distinguished professor of entomology at UC Davis (shown here in an almond orchard) is the newly selected editor-in-chief of the Journal of Economic Entomology. (Photo by Kathy Keatley Garvey)

Frank Zalom, distinguished professor of entomology at UC Davis (shown here in an almond orchard) is the newly selected editor-in-chief of the Journal of Economic Entomology. (Photo by Kathy Keatley Garvey)

Turning integrated pest management ideas into action

Pests have always been a bane of human existence. Modern society has developed effective pest management, “but there is no kind and gentle way to kill things,” said Brian Leahy, the director of the California Department of Pesticide Regulation, in remarks at the April 2018 IPM Summit.

The ever increasing incidence of invasive pests and the concerns about how to manage them will be a continuing challenge. Leahy said society is on a pest treadmill; and the best way to address it is with integrated pest management (IPM). 

The concept of integrated pest management emerged 60 years ago when scientists recognized that imposing a harsh chemical on a natural system threw it off kilter, often causing unexpected, usually negative consequences. They realized that combining an array of pest control methods – such as careful supervision of insect levels, promotion of beneficial insects, and using less harsh products – would be more effective, safer for families and farmworkers, and kinder to the environment in the long run.

And yet, pesticides are still widely used in agricultural, horticultural and structural systems.

“We need to make IPM more robust,” said Pete Goodell, UC IPM advisor emeritus who spent 36 years as an IPM researcher, leader and teacher. “We need to make IPM easier to adopt.”

Director of the California Department of Pesticide Regulation, Brian Leahy, listens as an IPM Summit participant shares ideas.

The meeting in Davis brought together nearly 200 people engaged in the science, business and regulation of pest management. They were assembled to address the tensions around pesticides and their alternatives, and usher in a new generation of researchers and practitioners to maintain and expand on six decades of progress in integrated pest management.

The IPM Summit is the final chapter of a collaborative effort titled “The Pests, Pesticides & IPM Project,” which was funded by DPR to enhance dialog about pest management. The project leader is Lori Berger, UC IPM academic coordinator.

“This project addresses the challenges pests pose to society,” Berger said. “We want to increase adoption of IPM practices on farms, and also in schools, homes, museums and golf courses. We're all in this together.”

UC IPM academic coordinator Lori Berger introduces UC ANR vice provost Mark Bell at the IPM Summit.

One example of urban IPM efforts was presented by the IPM Summit keynote speaker Kelly Middleton, director of community affairs for the Greater Los Angeles County Vector Control District. She outlined the substantial public health concerns associated with pest control in California's largest urban area. A primary target is mosquitos.

“In the early 1900s, vector control started with concerns about malaria and mosquito populations,” Middleton said.

Over decades, the vector control district worked behind the scenes to keep mosquito populations in check. But in recent years, new species of mosquitos capable of spreading Zika, West Nile encephalitis, chikungunya and yellow fever have made their way to LA, intensifying concerns.

A key IPM tool in Los Angeles is minimizing standing water where mosquitos can breed. With year-round water flow irrigating vast landscapes and concrete drainages that inhibit infiltration, the vector district is faced with mosquito breeding grounds created by “urban drool,” Middleton said.

Trash rife with nutrients – such as discarded food and plant materials – are perfect nourishment for immature mosquitos, a condition referred to as “urban gruel.”

Higher temperatures predicted because of climate change only threaten to exacerbate the problem.

“A warming world is a sicker world,” Middleton said.

An effective IPM approach to mosquitos is short-circuiting their reproduction opportunities by enlisting residents to maintain swimming pools, drain any receptacles that can capture rainwater or irrigation, and be vigilant about basins containing water in their environments.

These efforts are emblematic of the societal collaboration that can tackle pest problems without pesticides.

In his IPM Summit presentation, Goodell called for public sector investment in basic research, applied research, extension and education to find IPM solutions and encourage implementation. He appealed for IPM outreach to include community organizations, home owners associations and other non-traditional partners. He suggested agriculture take advantage of farmworkers' presence in the field for early pest detection.

“Technical pest management skills are critical, but it's connections with people that are key to bringing about change,” Goodell said.

 

Posted on Monday, April 23, 2018 at 9:19 AM
Tags: IPM (35), Lori Berger (2), Pete Goodell (2)
Focus Area Tags: Pest Management

2017 Kearney Alfalfa and Forage Field Day Presentations Now Available On-Line

As the alfalfa hay harvest season wraps up and we get in gear to attend the November 2017 Western Alfalfa and Forage Symposium in Reno, NV, we're...

Posted on Tuesday, October 24, 2017 at 8:00 AM
Tags: Alfalfa (7), Corn (1), Fertility (2), forage (3), IPM (35), Irrigation (2), Sorghum (3)

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