June, 2012

Green Sweat Bee

One of our most lovely native bees, the green sweat bee (Augochloropsis metallica) is actually one of several very similar looking species in the family Halictidae. Called sweat bees because some members of the family are attracted to the salts on sweaty skin, these brightly colored bees are often seen in gardens here in central Texas. Like many bees, female green sweat bees collect pollen to provide food for their young. Hairs on their legs hold the sticky grains. This individual is engaged in a specialized kind of pollen collection, performing what is known as buzz pollination, or sonication. While many flowers have pollen exposed on anthers, some kinds, including those in the nightshade family, have pollen contained within tubes. To get the pollen, the bee must vibrate its muscles as it holds the tube, causing the pollen to loosen and fall out the hole in the end. This bee is holding its leg underneath the opening to catch the yellow grains. Some of our commercial food plants require buzz pollination to bear fruit; the most well known example being the greenhouse tomato, which is usually pollinated by bumble bees.