Native bees come in a wide range of colors and sizes, from tiny sweat bees less than a quarter of an inch long to bumble bees over an inch in length. While some of these species may look like the familiar image of a bee with hairy yellow and black stripes, they may also be dark brown, black or metallic green and blue, with stripes of many colors. Most are solitary, with each female creating and provisioning her nest without the support of a caste system of workers. Most are unlikely to sting (Shepherd et. al., 2003).

The common names for native bees often reflect their nest building habits: miner, carpenter, mason or plasterer. Other names depict behavioral traits. For example, sweat bees drink salty perspiration to acquire nutritionally important minerals.

About 70 percent of native bees excavate underground nests (Potts et. al., 2005). Solitary bees dig narrow tunnels leading to a series of brood chambers, each one provisioned with a mixture of pollen and nectar and each holding a single egg (Michener, 2000).

About 30 percent of bees nest in wood tunnels, usually pre-existing holes such as those made by wood-boring beetles, but some will chew out the center of pithy twigs (Michener, 2000). Females of these wood-nesting bees create a line of brood cells, often using materials such as leaf pieces or mud as partitions between cells (O'Toole and Raw, 1999).

In the case of both ground-nesting and wood-nesting bees, once the nest is complete, the mother bee generally dies. Her offspring will remain in the nest, passing through the egg, larva and pupa stages before emerging as an adult to renew the cycle.

For some species this life cycle may progress over a matter of weeks, resulting in a second generation of bees in a single season. A few species may remain dormant for over a year. Most solitary bees however complete this life cycle over the course of a full year.

Native bees often only live for a few weeks as actively flying adults. They mate immediately upon emergence and the females begin nesting. They lay relatively few eggs compared to other insects, with a single female often laying less than 50 eggs before she dies. Male bees do not live long beyond mating, they do not collect pollen and have little value as pollinators.

While most of these wood-nesting and ground-nesting bees are solitary, some are gregarious, preferring to nest near others, a behavior that allows large aggregations to develop in favorable locations. Only a few tunnel and ground-nesting bee species ever develop truly social colonies, and often such behavior is environmentally dependent with some bees being social in one situation and being solitary in another (Michener, 2000).

The one group of strictly social bees native to the United States is the group of approximately 45 bumble bee species (Kearns and Thompson, 2001). Bumble bees live in a colony with a caste system of workers, males and a single egg-laying queen. Within this social structure, bumble bees share the labor of foraging and rearing their young.

Similar to honey bees, bumble bees construct a wax comb; however, this comb is not a symmetrical series of hexagonal cells, but rather is an abstract configuration of round wax pots, some containing brood and some containing small amounts of pollen or nectar.

Bumble bees nest in cavities such as abandoned rodent burrows, brush piles and grass tussocks (McFrederick and LeBuhn, 2006). The colony grows through three or four generations and, depending on the species, may have several hundred workers at the peak in mid-summer. Unlike honey bees, bumble bee colonies do not survive over the winter.

Bee Basics  

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