Mason Bees
Question from Tandy:
I have just happly become aware of your web site. I live in North San Diego County. What do you know about mason bees. Are they worth getting for pollination?
Photo by BobMacInnes 
Answer from Pat:
Yes it certainly is worthwhile encouraging mason bees, sometimes called the orchard mason bees, to set up housekeeping in your garden, particularly if you have a fruit orchard. Orchard mason bees (Osmia lignaria), are members of the Megechilid family of insects. They are gentle, beneficial, native bees prevalent in most parts of USA. They look a bit like small flies and their bodies are shiny blue with black legs. The males have long black antennae, and both males and females have black or gray hairs on their shoulders and bellies which make them good pollinators, especially of deciduous fruit trees. These bees are slightly smaller than honey bees. They make their homes in wood, for example in existing nail holes, knot holes, and crevasses, such as on the trunks of trees or in holes under the siding of homes or garden fences. They do not drill holes, like carpenter bees, but they clean out existing holes and then lay eggs that hatch into larvae.
Children also may be fascinated to learn about wild beneficial bees and thus not become afraid of them when there is no need for fear. On page 280 and 281 of my organic book I discuss several types of wild bees, including the mason bee, that are good to have in gardens. Orchard mason bees are actually better pollinators than honeybees especially since they pollinate in colder weather when honeybees are inside their hives trying to keep warm by buzzing. People who raise mild-climate apples, such as ‘Anna’ need the help of orchard mason bees especially since ‘Ana Apples’ often bloom in winter when temperatures are too cold for honeybees.
You can purchase blocks of wood that have been drilled with holes for orchard bees to nest in, but it’s best to purchase the larvae and install them into the blocks at the correct time of year. Just purchasing the blocks without the larvae may never attract orchard bees. Nonetheless, they may exist in your garden and perhaps you have never noticed them.
Pat, thank you for the reply. Nowhere else was I able to find much about
them. I assume the beneficial wasps are also good. I haven’t yet checked if
these can be purchased.
There are many types of beneficial wasps that help in pest control and do no harm to
people. One of the best known among the beneficial wasp species is the Trichogramma wasp. Trichogramma wasps are tiny flying insects that parasitize caterpillars but do not bite human beings. One can purchase Trichogramma wasps from purveyors of beneficial insects and release them in one’s garden to get rid of caterpillars. Here’s a video by P. Allen Smith on this subject. http://www.5min.com/Video/Beneficial-Insects—Trichogramma-Wasps-193900605
On more than one occasion P. Allen Smilth and I have been on the same speakers’ podium, but due to a fluke in our schedules we have yet to meet. A reader told me he once saw P. Allen Smith quote from one of my books on TV, so mentioning his video here gives me a chance to return the favor. From all I know of P. Allen Smith he is doing a great job of promoting wise garden practices. I thank him very much for recommending my book and I wish him well.
Will these beneficial wasps harm butterfly caterpillers? I have a lot of those.
Yes, but if they are green loopers, (the caterpillars that turn into “cabbage” butterflies), don’t you want those gone? Of course, you would not want harm to come to swallowtail butterfiles, yellow sulfurs, or morning cloaks. it’s all a question of creating a balance of nature, is it not?
Pat, can you tell me if anyone is able to raise mason bees in the Escondido, CA area? Gets pretty hot and dry here. I know HOW to raise and propogate them, just don’t know how well they’ll survive.
Thanks.
Yes mason bees will grow in Escondido. It is too hot for them in the desert but not in Escondido. The problem you might face, however, is pesticide use, especially lawn fertilizers containing white grub killer.
I tried Mason bees in suburban backyard Encinitas using a 56-hole Binderboard box from Pollinator Paradise in ID, http://pollinatorparadise.com/Market/Pricelist.htm, and cocoons from BeeDiverse in BC: https://beediverse.com/products-page/mason-bees/723-04-spring-mason-bee-cocoons-osmia-lignaria-duplicate/.
The bees did not reproduce well. I restocked with fresh cocoons twice. Perhaps the the Osmia lignaria from BC are not adapted to San Diego County climate. Perhaps the chemicals, especially in the manicured lawns were toxic. Perhaps the flowers in the area are not adequate for their pollen needs.
I would like information from someone who has experience propagating Osmia lignaria, or other native Mason bees, in the San Diego County.
I too have tried putting up homes for native bees and it never worked for me in my garden. I have not used any poisons in my garden since the 1950’s and I regretted it then! (None of my neighbors spray either.) Despite the homes for bees not working for me, I have had various species of native bees in my garden. My best successes have come from growing wildflowers. A way to bring bumble bees to your garden is to use ribbons that are designed to attract them. This helps to get squash pollinated. Look for the ribbons online. Secondly, I recommend growing zinnias in summer. When I have grown zinnias I have always had many bumble bees. They sleep in the flowers.
Next year plant wildflowers in November. You should have many native bees as a result. Secondly, don’t cover every bit of ground with mulch. Many native bees and especially bumble bees need ordinary uncovered and undisturbed soil in which to make their nests. Earthen banks are ideal for this. Unfortunately we have become too avid as munchers. Me too. I spread so much mulch on my garden there is nowhere left for native bees to make their nests. This is an unfortunate result of the success of otherwise beneficial organic gardening practices. Seems as if no matter how we meddle with Mother Nature we screw things up. Even when we want to help! I am not sure how we can escape from feeling badly about such things or even fixing them.
Finally, I grow wisteria on wooden pergolas and I have old wooden—not metal— garden furniture that I have painted bright Mediterranean colors. The carpenter bees make homes in the wood and then they pollenate the flowers of wisteria and other plants. They hit me when I get too close to their nests but they do not bite me. I dearly love them.
Seeking cocoons of Mason bees
I have had Mason bees in my garden for years. My experience is if you provide the right environment they will move right in. I have many wooden pergola’s and arbors as well as old redwood outdoor furniture I have had for years and have it repaired as needed and painted. Not all the wood is treated. Not sure where you can find cocoons. Suggest you look online. I am very friendly with bees and have found the round holes under the table where I often sit to eat. No problem. They sometimes butt me with their bodies saying “stay away from my nest!” but they never bite me. It is very important to use no pesticides.
I saw a mason bee house in a plant catalog but am wondering how I get the Mason bees to use it. I live in northern CA between San Jose and Palo Alto
Some catalogues and online sites are sources for eggs of mason bees, but the important thing is having the right climate. As I understand it, winter temperatures should be below 40 degrees Fahrenheit or mason bees cannot mature. Not sure if your climate qualifies. I suggest you phone your Farm Advisor or Master Gardener Hotline to get the answer to this question.