Bees

Bees are closely related to wasps and ants. Their common ancestor was an insect eater. The first bees evolved about 100 million years ago. Bees and flowering plants have coevolved to support each other, which is why bees are such efficient pollinators. There are over 20,000 species of bees worldwide and they are found on every continent except Antarctica.

Western bumble bee (Stephen Ausmus, USDA ARS) Public Domain

In San Jose, California, we have hundreds of native bees, with 4 predominant species:

• Western Bumble Bee
• California Carpenter Bee
• Green Metallic Bee
• Yellow-faced Bumble Bee

Honeybees are not native to North America; they were imported from Europe.

Green metallic sweat bee (I, Mike) CC BY-SA 3.0

Bee identification

Most people are familiar with the burning pain caused by a bee’s sting. This venom is produced in two exocrine glands and injected with a stinger when a bee feels threatened. Not all bee species have stingers. Honeybees are the only species that die after stinging.


Bees are distinct from other insects because they have bristles (setae) on their bodies, grooming combs on their forelegs, and many species have pollen baskets on the rear legs. If you are an entomologist (bug geek), you would also know that female bees have a divided 7th dorsal plate, but I’ve never noticed and I don’t think it makes much difference in the garden. 

Yellow faced bumble bee (junkyardsparkle) Public Domain

Bee description

Bees have five eyes. Yep, five. They have two very large, compound eyes that pretty much cover their head, and three small eyes (ocelli), which are used to gauge light intensity. Male antenna have 13 segments, while females have 12. These antenna hold many sense organs that can detect touch, smell, taste, and “hear” by registering air movement. Bees have a long proboscis for drinking nectar; imagine a tubular tongue with suction powers. A bee’s thorax has three segments, each with its own pair of legs. The back two segments also have membranous wings. Many bees are orange and black.


Bees range in size from the tiny (0.08”) stingless species, to the largest (1.54”) leaf cutter species, the giant mason bee (Megachile pluto).  Sweat bees (Halictdea) are the most common species in North America, but are often mistaken for wasps. The Arctic bee species, Bombus hyperboreus, actually attacks and enslaves other bees!


​Bee-havior (Sorry, I couldn’t resist!)

Most bees lives in colonies, but some bees are solitary. Honeybees, bumblebees and stingless bees live in eusocial  colonies that feature a queen, female workers, and male drones. The word eusocial describes a highly organized social construct in which brood is cared for collectively, overlapping generations live together, and labor division that creates castes that are either reproductive or not. Carpenter bees, leaf cutter bees, sweat bees, and mason bees are solitary. 


Every female solitary bee is fertile and builds her own nest. These nests can be in hollow twigs, in holes chewed from wood, or in the ground. Some solitary bees share nests, but they do not interact. These collectives are called aggregations. Solitary bees do not produce beeswax or honey, and there are no workers. Solitary bees are prolific pollinators, though they tend to specialize on a single or a few plant species. Some solitaries specialize in collecting floral oils or aromatic compounds! In cases where there is only one pollinator for a specific flower, threatening the existence of one species threatens the other.


There are four species of nocturnal bee. They have enlarged ocelli that are hypersensitive to light, but cannot form images. Most of these are found in high elevation jungles because of the flowers in those regions that bloom only at night.


Bee enemies

Bees have many enemies. Birds, such as shrikes, swifts, swallows, jays, and flycatchers catch them flight. Large wasps, called beewolves, frequently dine on bees. Robber flies and dragonflies are also known to eat them. Raccoons, mice, skunks, voles and bears love to eat bees and honey. [Did you know that beekeepers wear white because dark colors make us look too much like bears to the bees?]


Bees are also attacked by parasites, such as varroa mites and tracheal mites, and bacterial infections that cause sacbrood, deformed wing virus, chronic bee paralysis, and black queen cell virus. They can also catch a fungal disease called chalkbrood. Public concern has increased as Colony Collapse Disorder becomes problematic.


Human interactions

People have been collecting honey from beehives for over 17,000 years and raising bees (apiculture) for honey, pollination, beeswax, propolis and royal jelly for nearly 5,000 years. Professional beekeepers have shifted their focus from honey production to contract pollination. For example, California’s almond crop is the world’s largest managed pollination event, attracting a million hives to its orchards each year.


Despite advertising claims, royal jelly collected from queen cells and bee pollen harvested from drones has not been proven to provide health benefits to humans. In fact, royal jelly and bee pollen can cause allergic reactions that lead to fatal anaphylaxis. On the other hand, bee venom acupuncture has been shown effective against some types of arthritis pain and inflammation.


Bee lifecycle

All bees start out as an egg. Newly hatched larvae do not have legs, but they have horns on their head! These whitish grubs have 15 segments, jaws for chewing food, and a gland under the head that secretes a liquid that solidifies into a silk they use to build a cocoon. After encapsulating themselves, they enter a pupal stage where they go through complete metamorphosis and emerge as a winged adult. 


Bee gender is determined by whether or not the egg was fertilized. Fertilized eggs are born female and unfertilized eggs are male. Fertile females store sperm in their bodies and “decide” whether to lay male or female eggs. Eggs are laid in cells along with a food supply. 


In colonies, workers continually feed the larvae in a process called progressive provisioning. Worker bees also secrete royal jelly from glands in their head. It is used to feed the queen and all larvae, regardless of gender or caste, for the first three days of life. When a new queen is needed, several small larvae are selected and placed in special queen cells, where they are fed copious amounts of royal jelly. This treatment triggers the development of queens.


Bee communication

Social bees communicate with each other by dancing. The figure-8 “waggle dance” communicates the location of food with three pieces of information: sun position, the earth’s magnetic field, and the polarization pattern of the sky. (It boggles my mind, too. Don’t feel bad. You can learn more here.)


Bees as pollinators

All bees are pollinators, which makes them beneficial insects. They fly from flower to flower, collecting pollen and nectar for the hive or their brood. In doing so, they carry pollen grains on hairy legs and in pollen baskets to other flowers. Nectar, which contains mostly sugar, is a fast energy source. Most of the pollen, which provides protein and other nutrients, is fed to baby bees (larvae), but enough is dropped that bees are responsible for pollinating the lion’s share of earth’s flowering plants.


After collecting pollen, nectar, and tree resins, workers return to the hive. Tree resins are converted into propolis, which is used to increase the structural stability of the hive and to prevent pests and diseases from entering. Propolis is also used to mummify dead intruders that are too large to be carried out. Propolis is used by people as a varnish for some stringed instruments. Propolis has been claimed as a skin cure-all. It shows some effectiveness in treating cold sores and other mouth lesions, but all other claims have yet to be proven.


Bees in the garden

As beneficial as bees are, it is important that we, as gardeners, do what we can to help them. In particular:

• Install plants, especially natives, that provide pollen and nectar. [The UC Berkeley Urban Bee Lab has a great list]
• Avoid using pesticides and other chemicals.
• Create a water source, preferably one that keeps water moving.
• Educate and encourage others to do the same!