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Common Bee Groups in the San Francisco Bay Area
Focusing down on the San Francisco Bay Area, we have already identified 81 species of bees from the following five families: • Apidae It takes some study and practice, usually with a trained professional, before one can begin to identify bees to the family level, and then to the more difficult genus and species level. In our scientific work we strive to identify all bees to the species level, but we hope that the following general descriptions of the five families as well as the most common genera and species found in Bay Area gardens will help to open your eyes to the many interesting bees that are pollinating your flowers. We have also included references for more detailed descriptions of bee types. Apids constitute a highly diverse family of bees, which include social, hive-building groups like the honey bee as well as solitary groups which make individual nests in the ground or in tree holes:
• Ceratina, or small carpenter bees measure about 1/4 to 1/2 of an inch in length. Their bodies are long and slender and are metallic blue, purple or black in color. They have no obvious hair. Observing these skittish little bees requires some skill, however, once the general form and color of the abdomen are recognized, there is no mistaking them.
Colletids are regarded by some taxonomic specialists as a group of primitive bees. They are mostly solitary in habit. There are two subfamilies and members of both are found in the Bay Area. Due to their small size, Colletids are very difficult to photograph. • Species of the Colletinae subfamily are mostly robustly hairy bees, up to 3/4 inch in length, which resemble anthophorid bees in general appearance.
• The group Halictus, like most species in the Bay Area, have elongated abdomens that are black with light colored bands. • The Females of the colorful species Agapostemon texanus are metallic green, and the males have metallic green thoraxes and yellow and black striped abdomens. Females of this group carry pollen on their legs, but often the pollen is also loosely affixed to forelegs and the sides of the abdomen.
• One group, Osmia, can be observed only during the spring and early summer period. Osmia are shiny metallic blue-black, bluish, or green depending on the species. They are a delight to observe rapidly visiting ornamental flowers such as Salvia mellifera and Clarkia unguiculata. • The largest Bay Area megachilid is Megachile perihirta (pictured above-right). It is about the same size as a honey bee. It can be observed at close range from spring to early fall visiting a wide variety of plants, and especially Coreopsis species, Cosmos bipinnatus, C. sulphureus, and Helianthus annuus. During the late summer -early fall another large megachilid, Chalicodoma species, can be occasionally observed on flowers of Bidens ferulifolia, Cosmos bipinnatus, and Helianthus annuus. This bee is easily recognized by the elegant color pattern of gold and black bands on its abdomen. (photo on cosmos).
"Small and medium bees" Some plants such as Calendula species, Geranium incanum "Sugar Plum", or the buckwheats characteristically attract small or medium sized bees (photos). We are not always able to identify those bees on flowers when we make field observation. For convenience we refer to these plants as having small or medium bees until we have enough information for at least a family name for these groups of bees. In the case of the small bees, they often turn out to be members of the family Halictidae or rarely Colletidae. Medium bees usually are megachilids.
General Info On Our Plant Recommendations
The bee plants listed in this section are the ones that we have evaluated in the San Francisco East Bay Area for their attractiveness. We have listed mostly the smaller plants that can be grown rather quickly in gardens. Trees and large shrubs attractive to bees are not covered here – they can be found in the General List of known bee plants. In the following Most Attractive Plant List we provide only the essential characteristics of the bee plants, which should be useful for anyone planning a bee or pollinator garden. We advise readers to consult the Sunset Western Garden Book (2001) for more complete information on the plants, vegetative characteristics, their history, variations, and preferred soils and other preferred growing conditions. We expect this list of recommended plants to grow as we learn more about the floral preferences and behaviors of urban bees. We also continue to learn about new plants and new varieties of our listed plants that are attractive to bees. In this regard, several gardeners and nursery persons call new discoveries to our attention, which we follow up with evaluations whenever possible.
Specific References: For more information, detailed descriptions, and colorful images illustrating all bee families mentioned above, we recommend the following sources: 1.) American Association of Professorial Apiculturists ** Look especially for their useful Technical Bulletin No. 2 (1999) entitled, "Bee Pollinators in your Garden." 2.) Bees of the World. 1991. C. O'Toole and A. Raw. Blandford Publishing - Facts on File, Inc., 460 Park Avenue South, NY NY 10016. **This is an excellent source of information on bees worldwide. The numerous color photos are truly outstanding. 3.) Pollinator Conservation Handbook. 2003. M. Shepherd, S.L. Buchmann, M. Vaughan, and S.H. Black. The Xerces Society, 4828 Southeast Hawthorne Blvd., Portland, Oregon 97215. **This is a new excellent booklet that addresses a wide variety of current bee and other pollinator issues. The color photos (some by Dr. E.S. Ross) are excellent to outstanding. This handbook is highly recommended.
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When
most people think of bees, the first bee that comes to mind is the
honey bee. But this bee is only one of about 25,000 species known
worldwide. In the U.S. we have almost 4,000 and in California slightly
more than 1,500 species have been recorded. One reason for high
species diversity in our state is the diverse flowering plants that
can be found in a wide diversity of habitat types.
•
The most common social member of the Apids is the honey bee, Apis
mellifera, which is an introduced (exotic) species from Europe.
Honey bees measure about 3/4 of an inch in length. They are easily
recognized by their slow flight and flower visitation. They come
in a range of colors from blond to black and usually have brown
bands on their abdomens. This bee carries pollen neatly in 'pollen
baskets' or hairs specially developed to collect pollen on their
hind legs.
•
Bumble bees, or Bombus species, are another common social
group of apid bees in the Bay Area. They are often larger, rounder,
and have more hair than honey bees. They are usually black with
1 or 2 yellow stripes, and are called 'bumble bees' because of their
bumbling flight pattern. Like the honey bee, this bee group carries
pollen, sometimes in large yellow or purple blobs, in pollen baskets
on its hind legs.
•
Anthophorids or digger bees are medium-sized compared to
honey bees. They are fast flyers and visit flowers rapidly and efficiently
compared to honey bees. They are often quite hairy, and females
appear roundish when their hind legs are packed with pollen. the
most common genus of anthophorid is Melissodes, which contains
two species, both of which are a little smaller than honey bees.
Males (with long bodies and antennae) and females (roundish bodies
and short antennae) are commonly found during the summer on flowers
of Cosmos spp., Helianthus annuus, Scabiosa
spp., Coreopsis spp., and Bidens ferulifolia (photos).
At night male Melissodes can often be found sleeping together
in flowers of Cosmos bipinatus.
Another
prominent, but less common anthophorid, is Anthophora urbana
. It is a fast flying, compact bee about the size of Melissodes
females. It has a grayish thorax and a distinct black and
white banded abdomen and visits a wide variety of ornamental flowers
in spring and summer.
•
Carpenter bees, or Xylocopids, look a lot like bumble bees,
especially with regard to size and their rounded body shape. They
differ from bumbles in that they are mostly solid, shiny black,
have little hair, and the top of the abdomen is flattened.
Andrenids
are solitary spring bees, small to medium sized compared to honey
bees, and also carry neatly-packed pollen on their hind legs. Most
of the Bay Area species are shiny blue-black with torpedo-shaped
abdomens, but some have beige or brown hair covering their thoraxes.
These bees are not as common as other spring bees, however, we have
observed them with some consistency on Phacelia tanacetifolia,
Gilia capitata, and some chard and kale plants.
•
Bees of the Hylaeinae subfamily are very small and wasp-like,
about 1/2 an inch in length. Most species are black with conspicuous
yellow markings on their faces. In contrast to other bee groups,
females of this subfamily carry pollen in the crop, which is the
specialized anterior portion of the digestive tract.
Halictids
are common spring and summer bees, small to medium in size, with
long bodies. They are very diverse in lifestyles, including solitary,
semi-social, and primitively social species. As a group, the halictids
are commonly observed visiting a wide variety of ornamental flowers.
Upon close examination at pollen flowers such as California poppy
(Eschscholzia californica), females can be observed gathering
pollen on their legs, especially the hind legs. During this process,
they will also commonly have pollen messily spattered on the sides
of the thorax and abdomen, as opposed to the neat pollen-carrying
baskets of the honey and bumble bees.
Megachilids
are known as leaf cutting and mason bees. They are a large, diverse,
and common group of bees found in the Bay Area. They range in size
from small (1/2 an inch) to honey bee size, and most are strictly
solitary. The most common Bay Area species are dark gray with distinct
light-colored banding on the abdomen. In sharp contrast to the other
families, megachilid females gather pollen on the underside of the
abdomen by means of a series of stout hairs that protrude from several
body segments. While visiting flowers, some female megachilids arch
their backs, elevating their abdomens and showing their densely-packed
and often colorful pollen loads. Although megachilids are found
during the entire growing season, certain groups can only be found
during specific seasons.
We
refer to bee plants as those that have measurable attraction to
urban bees. These are plants that are regularly visited by bees
for their pollen and nectar resources.
Regarding
visitors, you will notice that with each plant we have provided
major categories of associated bees and other flower visitors. Descriptions
of the bee groups can be found below. At times we refer to flower-visiting
bees as sb (small bee), mb (medium bee), or lb (large bee). This
occurs when flower visits are too rapid or we fail to net the bees
for more accurate taxonomic determination. As time goes on and we
make more observations, these vague bee-size categories will be
changed to actual taxonomic groups (section of web site).
Many
of the bee plants also attract a wide variety of other flower visitors.
When this occurs with regularity, we list these visitors as major
groups such as: beneficial flies (usually hover flies); beneficial
wasps (many are carnivorous species looking for prey insects feeding
on plants, but some visit for nectar); and butterflies seeking
floral nectar. A few of the bee plants also attract hummingbirds,
such as Salvia uliginosa (pictured at right). Needless to
say, with careful planning, gardens can become important micro-habitats
for a wide variety of beneficial pollinators. In fact, by concentrating
known pollinator plants in a small area, one can actually experience
more insect life than in a wildland area where flower visitors
are more widely spread over a landscape.