BEES VS. WASPS A male wasp (Trypoxylon californicum). Wasps are the insects that most people see at their picnics, especially yellow jackets. While they can be irritating at times, they do serve an important ecological function. They are predators of many insects, especially crop eating insects. Parasitic wasps are beneficial because they can be released into agricultural systems, serving as a natural biocontrol of insect pest populations. They lay their eggs on or inside their host and as the wasp develops it feeds on its’ host. The hosts are usually considered garden pests, such as tomato hornworms, aphids, cabbage worms, armyworms, and strawberry leaf rollers. After the parasitic wasp completes development, it emerges as an adult and kills the host. Wasps also serve as food for many other species, like birds, and thus contribute to the food chain. Also, because some species visit flowers for nectar, they can be inadvertent pollinators. There are hundreds of species of wasps in California, and like bees, they are part of the heritage of the land. In the San Francisco Bay Area some of the most common wasps are yellow-jackets, paper wasps, mud daubers, sand wasps, thread-waisted wasps, and potter wasps. Wasps and bees are often mistaken for each other, but knowing a few key features of both can help one tell them apart. Bees gather pollen and nectar from flowers to use as food for their offspring. Wasps are carnivorous, and hunt for other insects or spiders, but some also visit flowers for nectar. Bees usually have very hairy bodies and pollen collecting hairs on their legs or under their abdomen to help them accomplish this task. Wasps tend to have few to no hairs at all because they don’t intentionally collect pollen. BEES THAT LOOK LIKE WASPS:
Some bees look like wasps because they don’t have much hair on their bodies. They collect pollen and store it internally in their crop instead of on the outside of their bodies. Some other relatively hairless bees, such as cuckoo bees, don’t collect pollen because they lay their eggs in the nests of other bees. Wasps usually have more elongate bodies, longer legs, and sometimes have what looks like a pinched waist, whereas bees usually look more compact. There are other physical differences between bees and wasps, but they are hard to make out without the use of a hand lens or microscope. So, if you see a busy creature flying from flower to flower and actively collecting brightly colored pollen, then you can be fairly sure it is a bee. Bees actually evolved from predatory wasps (apoid wasps), so bees and wasps have a lot of similarities both in appearance and behavior. Bees and wasps both have two sets of wings, unlike flies, which only have one. Also, only the females of bees and wasps can sting because the stinger is actually a modified egg laying apparatus. Behaviorally, they are similar in that they both have social and solitary species. Yellow jackets, like bumble bees, have seasonal colonies that form in the spring and die out in the late fall with the queens overwintering to start a new colony the following year. The majority of bees and wasps though are solitary, and the female does all the work of building and provisioning nests for her young. One wasp that a lot of people confuse with bees is the yellow jacket. Unlike honey bees, yellow jackets and other wasps don’t leave their stinger behind when they sting something, therefore they are able to sting several times in a row. These social wasps form papery nests both above and below ground that can contain anywhere from 50 to 5,000 individuals. The larger the colony gets, the more aggressive the wasps become. This usually happens in late summer/early fall when food is in short supply. Yellow jackets then become nuisances at picnics, eating whatever they can find. The adults will sting and paralyze insect prey as well as scavenge from carrion to provide as food for their offspring. As adults they mostly feed on nectar, honey dew, and rotting fruit.
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 Introduction The model of a ‘Bee Hotel’ has been a useful tool for surveying insects in research studies for decades. However, in recent years, the concept of a bee hotel has entered the mainstream; capturing the attention of naturalists, gardeners, and those alike. With this transition, it has gained its name and evolved to take on various forms that hardly resemble the humble wooden box model used in research. Increased interest in creating spaces for bees is hopeful, as it signifies a positive trend in attention to pollinator livelihood. The UC Berkeley Urban Bee Lab has had great success with simplistic wooden box models of bee hotels in our Costa Rica Bee Project. We share here some of the knowledge we have gained through numerous years of research working with bee hotels in both Costa Rica and California. Additionally, we offer some considerations to ponder when creating your own bee hotel, acknowledging the limitations that they hold, especially in regards to a changing climate. The Bee Story Bee hotels offer a straightforward method of surveying cavity-nesting bee populations. This approach of surveying insects has been around for many decades, as the wooden-box model was described in the 1967 book, “Trap-nesting wasps and bees: life histories, nests, and associates”. Through the use of bee hotels in our Costa Rica Project, we were able to gain considerable insight into seasonality, emergence, and patterns of nesting preference. We attribute much of our success in this project to our commitment to mimicking natural conditions of cavity-nesting* bee habitats. Our personal model of a bee hotel is a simple wooden block with at least 3 inch holes drilled inside. Additionally, we scatter our models widely to be consistent with patterns observed in natural settings. Scattering the models aids in reducing the risk of predators or parasites, as opposed to clustering cavities together, which in turn could create a ‘buffet’ for predators and parasites. Left: An example of an artistic display of a bee hotel in Costa Rica.  Left: Wooden box model used in the Urban Bee Lab Costa Rica Project. Considerations By implementing bee hotels in our Costa Rica Project, we observed a significant abundance of bee hotel occupants. However, it is important to acknowledge that these observations come from a time when the effects of anthropogenic climate change were not nearly as pronounced. While we support that mimicking natural conditions is in part attributable to the great number of cavity-nesting bees observed in our bee hotels, we speculate that if this study was recreated today there would be considerably fewer bee occupants due to the extensive decline in species since then. Around the world, ecosystems are under threat due to the velocity of climate change. A vast number of insect species are collapsing at an alarming rate, which could reap devastating consequences as described recently by Milman in, “The Insect Crisis: The Fall of the Tiny Empires that Run the World”. In California, longer periods of drought and increased temperatures are contributing to a tremendous loss of biodiversity. In combination with a reduction in species diversity, unusual climatic phenomena are impacting the phenology of a number of bee species. A study published in 2018 conducted an analysis on the effects of warming on Osmia ribifloris**. It was found that experimental warming resulted in a greater variation in emergence times of O. ribifloris, with an overall trend in delayed emergence (CaraDonna et. al, 2018). On a broader scale, fewer bee species have been recorded since the 1950s with an alarmingly sharp decline of bee species from 2006 to 2015 with approximately 25% fewer species recorded (Zattara & Aizen, 2021). Both findings are consistent with observations we have made in the field. What does this have to do with Bee Hotels? Other Hotel Guests With a reduction in species diversity, there are overall fewer bees to occupy bee hotels leaving a vacancy to be filled by other inhabitants. As we have observed in the field, hotel guests can include: ants, spiders, wasps, earwigs, crickets (and even small frogs as we have seen in our Costa Rica Project!). Caution in Cleaning out Hotels Many often choose to clean out their bee hotels after a year of use to make room for new occupants. However, with the recent trends of delayed emergence in mind, as well as the potential for other inhabitants, it is important to check inside your bee hotel before cleaning it out. Potential Alternative: The Bee Garden Bee gardens create habitat for all varieties of bee species. By contrast, bee hotels can only be of use for cavity-nesting bees, which make up a much smaller percentage of the bee species in an area (roughly 30%). Bee hotels can be beneficial by providing habitat for cavity-nesters, but their effectiveness is not nearly as great, or proven as bee gardens. We have found bee gardens to be successful in attracting a wide range of bee species. In Ukiah (northern CA), we sampled bees over 2 years in 2007 and 2008 in a small residential garden that fortuitously had diverse bee plants. We also added some known bee-attractive plants to the garden. The sample yielded 68 bee species; city wide 91 bee species were known. Here at UC Berkeley, we built a diverse pollinator habitat garden in an open bare dirt field at the UC Berkeley Oxford Tract. After a few years of plant growth and development, we sampled the garden for bee species. The sample yielded about 65 native bee species. If you are someone who is interested in contributing to the preservation of native bee populations, planting a bee garden may be a more viable option. Considering the established effectiveness of bee gardens, we prefer them over bee hotels or in conjunction with. If you are planning to build a bee garden in your own yard, we encourage you to pack in plant species that have proven to attract bees and encourage that the bigger the garden the better!  Above: The image is of a large urban garden in Brentwood (Contra Costa Co.) CA. Our Recommendation: Being mindful of the considerations and limitations of bee hotels is essential to ensuring that they help bee species, rather than cause harm. As noted before, we encourage sticking to a simple model, ensuring that the holes are deep enough (3+ inches) and scattering bee hotels rather than clustering them together. While artistic displays can be attractive, they are not necessarily effective. Our personal approach is to avoid cleaning out hotels completely. Rather, we relocate them to a preferably wild area where natural elements can take over and reuse the holes; or where late emergers can take their time to emerge, perhaps over more than one year. If you are eager to clean out your bee hotel, we strongly recommend taking a look inside using an LED light before doing so as there may still be occupants! *Bee species that lay their eggs and nest in hollowed out chambers of wood. ** A cavity-nesting bee species that is found throughout the Western and Southwestern United States. Helpful Articles: http://www.helpabee.org/seasonal-bee-gardening.html http://www.helpabee.org/best-bee-plants-for-california.html References CaraDonna, P. J., Cunningham, J. L., & Iler, A. M. (2018). Experimental warming in the field delays phenology and reduces body mass, fat content and survival: Implications for the persistence of a pollinator under climate change. Functional Ecology, 32(10), 2345–2356. https://doi.org/10.1111/1365-2435.13151 Frankie, G.W., R.W. Thorp, J.C. Pawelek, J. Hernandez, and R.Coville. (2009). Urban Bee Diversity in a Small Residential Garden in Northern California. Jour. Hymenoptera Research. 18(2): 368-379. Zattara, E. E., & Aizen, M. A. (2021). Worldwide occurrence records suggest a global decline in bee species richness. One Earth, 4(1), 114–123. https://doi.org/10.1016/j.oneear.2020.12.005 Krombein, K. V., & Krombein, K. V. (1967). Trap-nesting wasps and bees: Life histories, nests, and Associates. Smithsonian Press. Packer, L. (2023). Bees of the world: A guide to every family (guide to every family, 5). Princeton University Press. Milman, O. (2023b). The Insect Crisis: The Fall of the Tiny Empires that Run the World. W.W. Norton & Company. Nesting Resources. Xerces Society. (n.d.). https://xerces.org/pollinator-conservation/nesting-resources#:~:text=Cavity%20Nesting%20Bees,pieces%20of%20bamboo%20for%20nesting. Written by: Emma Coflin [email protected]  For those interested in learning more about bee identification, the UC Berkeley Urban Bee Lab has been utilizing the book Common Bees of Western North America published in 2023 by authors Olivia Messinger Carril and Joseph S. Wilson. This book provides an excellent introduction to bee biology and anatomy for individuals of all entomological experience levels, especially beginners, who are hoping to familiarize themselves with the various bee genera of western North America. The images contained in this book are of incredibly high quality, displaying the most important characteristics of bee identification. Two incredibly useful features of this book are the “Quick Reference Guide to Bees of Western North America” which provides readers with a helpful starting point to identify bees based on color and size, along with an actual representative size and shape silhouette found beside each species account throughout the book. Though the description of bee genera is very detailed and inclusive, it is important to note that the authors chose species they found to be most representative of the genera and do not include all of the roughly 1600 species found in California, let alone the more than 3000 species found in western North America. For the non-included species of bees, the authors provide plenty of selected references for the more experienced audience to identify bees at a more advanced level. To aid in general bee identification with a microscope, the highly detailed and simple-to-understand dichotomous key at the back of the book has been a useful step-by-step tool in helping researchers identify bees to genus.
A microscope is not necessary to enjoy the many images in this book and familiarize yourself with the great diversity of bee genera in western North America, but is necessary for putting this book into practice. The level of identification performed at the Urban Bee Lab requires a binocular stereo microscope, which can be purchased relatively inexpensively online at Forestry Suppliers and Ward’s Science. Credit: Jerid Vega <[email protected]> and Gordon Frankie <[email protected]> In this richly illustrated guide, Bees of Costa Rica, leading bee experts showcase the diversity of bees in Costa Rica and the multitude of ways in which they interact with flowers and people. Thoughtfully compiled and designed for a wide variety of audiences, Bees of Costa Rica is based upon years of biological research of the native bee species of the tropical country. Originally published in Spanish by The Universidad de Costa Rica as Abejas de Costa Rica in 2021, this newly updated 2023 edition has been translated into English and is published through Cornell University Press. With identification keys and more than 150 high-definition color photographs, Bees of Costa Rica is essential for anyone looking to learn about and protect these important pollinators in Costa Rica and beyond. Costa Rica is home to 117 bee genera and approximately 700 bee species. Focusing on the five bee families present in Costa Rica, the authors describe the bees' general physical traits, foraging and mating behavior, and nest characteristics. Chapters cover the relationships between bees and other insects, profiles of plants pollinated by bees, and practical suggestions for bee conservation.  Chapters 1, 2, 4, and 5 cover general topics about bees including their importance, biology, behavior, nest associates, and relationships with flowers. Chapter 3 provides detailed profiles of the 5 families of bees found in Costa Rica and includes an informative look at the 51 most common Costa Rican bee genera out of the 117 known within the families. The amazing colored images are invaluable tools to aid the reader in bee identification.
Chapters 6 and 7 present rich information on the plants known to attract bee visitors. Chapter 6 provides an overview of wild and ornamental type plants, while Chapter 7 covers crop plants. There are thousands of plants known to attract the almost 700 bee species recorded in Costa Rica, but the ones selected for the book serve to illustrate the variety of plant types that are well known to have consistent associations with bees. Chapter 8 presents readers with case histories of how human activity has both positively and negatively impacted Costa Rican bee populations. Examples of privately inspired projects to conserve bees and their plants are described, providing inspirational models for others to copy and follow in future endeavors. The authors acknowledge the diverse contributions of numerous Costa Rican and foreign researchers who have published scientific information used in the preparation of this volume. Credit: Cornell University Press, Gordon Frankie ([email protected]), Rollin Coville ([email protected]), Sara Witt ([email protected]), Jerid Vega ([email protected]) Spring is in full bloom, and so is our lab garden! Here is a peek at what we are currently growing, and some of the bees our garden is attracting.
The california poppies have been attracting all kinds of bees, from Agapostemon texanus to Bombus vosnesenskii to Halictus ligatus and everything in between!
Habropoda and Anthidium have been fans of the Salvia 
The rock purslane is popular with the Halictids and Andrena
Our resident artist, Leilani, has been working hard on decorating our lab with her beautiful art. On the left is a poster featuring Agapostemon texanus and on the right is her mural of Megachile fidelis! Up next is a mural of a hummingbird.
 Five students from the UC Berkeley Bee Lab went on a field trip on Saturday April 2, 2022 to visit the Frog Hollow farm, where they had the opportunity to chat informally for 2 hours with the owner/manager, Farmer Al. Farmer Al generously told us the history of the farm and how it has grown over the years from 23 acres to 280 acres today. He commented on how the CSA program is now up to ~ 1500 members, and how he and his staff manage to keep up with the boxes of fresh fruit that are sent out each week to subscribers. We also learned about the major compost project and how he is enriching his soils with all the organisms that are part of the compost ecosystem. Finally, we learned about the incredible pastries that his wife Becky continues to produce.
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