Recently I went into my vegetable garden to visit the squash bees. They come out every year at this time when plants in the Cucurbitaceae family bloom. Cucumbers, melons, squash and pumpkins are just a few of the cucurbits they visit to gather pollen. The males just hang around to breed so that the females can build a nest and lay eggs.
Squash bees are among the 1,600 bees native to California and just one of the many types of native bees that visit my garden. The female builds her nest in the ground so be sure to leave some ground bare of mulch or other coverings.
Napa County Master Gardeners began studying bees when reports emerged of the declining honeybee population. We learned that some bees like to nest in holes in wood, so several of us built nests out of wood. I made several. The one I made from a piece of log with a little roof on it has done the best. It's a nest for mason bees.
I knew the bees were there, but I didn't actually see any until I took the nest to an event for schoolkids at the Napa County Fairground. A bee came out, hung around for a while and then flew away. This was in March when the fruit trees were starting to bloom. About 30 holes were filled in the nest log, each with several bee eggs. A male always hatches first; females follow.
I watched the nest log a lot over the next few weeks. The bees had hardly emerged when they began building new nests. Now, once again, 30 holes are filled and the eggs should hatch next spring.
Bumblebees have been present in my garden for several years. They love my Salvia macrophylla ‘Hot Lips', which is native to Mexico. Sometimes the plant is covered with bees, mostly bumblebees.
Last spring I learned about the teddy bear bee (Xylocopa varipuncta), a common name for the male Valley carpenter bee. I was working in my garden when a big yellow bee approached me and buzzed slowly back and forth in front of me. He was an attractive bee, so I went inside to research him and identify who was visiting me. I learned that the males have no stinger and can be an inch long. He was definitely the biggest bee I have ever seen.
If you want to draw these bees to your garden, plant California native plants. The native bees and plants developed together. Honeybees were imported to this country because they produce honey. However, they have had many health problems over the past years.
Scientists are studying how native bees might play a bigger role in pollinating crops. About 100 food crops need pollination annually to produce fruit.
I even find bees in my garden in winter. I have a clematis that blooms in December and January. When I go out in the cool of the day, I find bees sleeping in the blooms. I never linger long enough to identify which type of bees they are, but I like knowing they are still flying.
Among the other native bees are digger bees and sweat bees. Some native bees are as tiny as gnats. Seventy percent of bees nest in the ground and the rest in wood holes.
At one time, I had many paper wasps building nests in my garden. They were docile around me, and they did gather insects for their nests. One winter a queen wasp overwintered on a door in my shed. I would go in periodically to check on her. She had many small wasps gathered around her, but their numbers kept declining so I often wondered if she ate them to get her through the winter. Eventually she was the only one left in the shed.
If you would like to learn more about native bees, you can find many resources online. California Bees and Blooms: A Guide for Gardeners and Naturalists by Gordon W. Frankie, Robbin W. Thorp, Rollin E. Coville, and Barbara Ertter is an excellent reference. You can also consult www.helpabee.org.
Tree Walk: Join U. C. Master Gardeners of Napa County for a free guided tree walk through Fuller Park in Napa on Monday, August 8, from 10 a.m. to 11:30 a.m. Registration is recommended as space is limited. Meet at Fuller Park, corner of Jefferson and Oak Streets. Online registration or call 707-253-4221. Trees to Know in Napa Valley will be available for $15. Cash or check payable to UC Regents. Sorry, we are unable to process credit cards.
Workshop: The U. C. Master Gardeners of Napa County will host a workshop on “Growing Fall and Winter Vegetables” on Saturday, August 13, from 9:30 a.m. to 11:30 a.m., at the University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Discover the joy of harvesting vegetables from your own garden in fall, winter and early spring. Topics will include timing, watering, fertilizing, managing pests and harvesting. On-line registration (credit card only). Mail-in/Walk-in registration (cash or check only).
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.