The purpose of this listserve is to disseminate information and foster discussions regarding the inventory and monitoring of bees as well as their identification.
Sweat bees, also referred to as halictid bees, (Halictidae) are so named for their habit of landing on people and licking the perspiration from the skin in order to obtain the salt. Bees in this family are common throughout North America, with over 1,000 species occurring in North and Central America. These bees are small to medium sized and generally are black or brown colored. However, there are species of sweat bees that are bright metallic green or brassy yellow.
This family of bees engages in a behavior called sonication, or buzz pollination. The bee places the anther in its jaw and vibrates each flower with its flight muscles, causing pollen to be dislodged. Wild blueberry (Vaccinium spp.)crops are more effectively pollinated through buzz pollination, and sweat bees do pollinate this plant. These bees visit between four and eight flowers per minute and carry significant pollen loads on their hind legs. Additionally, sweat bees are generalist feeders - they feed on, and subsequently pollinate, many different flower types. These behaviors and adaptations make sweat bees efficient pollinators. Examples of crops pollinated by sweat bees include blueberry (Vaccinium spp.), alfalfa (Medicago sativa), and watermelon (Citrullus lanatus). Other plants that benefit from sweat bee pollination include Brazilian orchids like Prescottia densiflora and Campylocentrum aromaticum , shadbush or serviceberry (Amelanchier spp.), moosewood, rhodora (Rhododendron, Subgenus: Pentanthera), and raspberry (Rubus spp.). One of the most well-known sweat bees is the alkali bee (Nomia melanderi), a great pollinator of alfalfa.
A sweat bee (Halictus spp.) covered in pollen. Photo copyright Bill Claff.
Sweat bees generally are solitary bees. However, there are a few species of sweat bees that are considered to be eusocial. Solitary bees usually build and live in individual nests rather than in a hive or with a colony of bees, while social or communal bees do live colonially in hives or bee communities.
Description:Bees in the sweat bee (Family: Halictidae) family are small to medium sized, ranging from 4 to 10 mm. They generally are black or brownish colored; however, there are species of sweat bees that are metallic green and some that have yellow or red markings. Males tend to have yellow faces.
Life History:Sweat bees have a range of nesting habits, although all sweat bees are ground nesters. Some species have dispersed solitary nests; others are gregarious with densely situated nests and primitive social arrangements. Females dig branching burrows in loose soil. Each burrow ends in a single cell, in which the female deposits eggs and a pollen ball upon which larvae feed. Females mate before hibernating for the winter and begin nesting in early spring. Daughters are raised first, with males being raised in late summer or early autumn.
Habitat:Sweat bees build nests in clay soil, sandy banks, and cavities in weeds or shrubs.
Distribution:This bee family is found throughout North and Central America.
