Posts Tagged: wasps
I was lucky enough to attend the recent “Pollinator Gardening” workshop hosted by the California Center for Urban Horticulture at UC Davis. Part of CCUH’s Your Sustainable Backyard series, the day devoted to pollinators was fascinating. I learned a lot, which was the point:
- Bees are basically wasps that have changed their diets. Wasps = carnivores. Bees = vegans. Nectar is their flight fuel, and they use plant protein (pollen) to feed their young.
- Boy bees do not sting.
- Not all bees are social, like European honey bees. Many native bees are solitary, nesting in soil or fallen trees. Very few bees make honey.
- There are 20,000 species of bees, on a world scale. This is more diversity than all mammals and birds combined.
- In North America there are 4,000 species of bees.
- In California there are 1,600 species of bees.
- In Yolo County, there are 1,300 species of bees.
- The value of pollination is $220 billion a year in the U.S. European honey bees’ pollination value is $14.6 billion a year. Wild bees? $13 billion a year.
So, I got it! Wild bees are quite helpful pollinators after all. But they are under threat from habitat loss, the intensification of agriculture, new and persistent diseases, and pesticides. It was made plain during the workshop that we, as urban gardeners, should to do our part to provide bee-friendly areas in our yards. How do we do that?
We were told that bees need habitat, not just flowers. They need bare soil, so don’t use too much mulch. They also need sun, plenty of water, rocks and a diverse selection of pollinator plants (native plants work best). You can even make your own bee houses out of reed cane bundles. If you build it, they just may come. (To see a bee-friendly garden, head to UC Davis’ Haagen-Dazs Honey Bee Haven.)
A female Valley carpenter bee (Xylocopata varipuncta) forages for nectar in a Jerusalem sage (Phlomis fruticosa) bloom. (photos by Kathy Thomas Rico)
A male carpenter bee (Xylocopata tabaniformis orpifex) visits a Salvia blossom in a Vacaville garden.
An article in the Merced Sun-Star today declares that wasps are in full force this summer. Reporter Carol Reiter set out to determine why and what to do.UCCE farm advisor Maxwell Norton told her he suspects the high number of local homes abandoned due to foreclosure has boosted the wasp population.
"So many abandoned homes means that they are multiplying unabated," Norton was quoted. "Garage eaves and home eaves give them a lot of places to build their nests and be undisturbed."
Reiter also spoke to Mary Louise Flint of the UC Integrated Pest Management Program. She said yellow jackets are aggressive and can pose problems for humans; paper wasps, on the other hand, won't usually sting unless they get trapped. Unfortunately, it's hard to tell the difference.
The UC IPM online guideline for "Yellowjackets and other social wasps" says some social wasps provide a great benefit by killing large numbers of plant-feeding insects and nuisance flies; others are exclusively scavengers. Wasps are only a problem when they threaten to sting.
The guideline provides information on preventing and trapping wasps, but the advice for spraying will probably discourage all but the most fearless homeowners from doing it themselves.
"Wasps will attack applicators when sensing a poison applied to their nests, and even the freeze-type products are not guaranteed to stop all wasps that come flying out," the guideline says.
UC Master Gardener wasp identification illustration.