by Susan Pohlen, Elm Fork Chapter
One of my favorite sessions at the 2011 annual Master Naturalist conference was about bumblebees of Texas. Michael Warriner, Texas Parks and Wildlife Division, provided an interesting look into the life cycle of bumblebees. He began by differentiating between honeybees and bumblebees, and then provided examples of insects that are often mistaken for bumblebees. He identified Texas species of bumblebees, and the bumblebee life cycle.
What a bumblebee isn’t: Bumblebees are not honeybees. It’s actually quite easy to distinguish between honeybees and bumblebees because bumblebees are roughly twice the size of honeybees. Two flying insects often confused with bumblebees are the Snowberry Clearwing (moth), and the eastern carpenter bee. Whereas bees will actually land on plants, the moth will hover in front of the plant much like a hummingbird. The eastern carpenter bee is the insect most often confused as a bumblebee. You can identify the carpenter bee by the lack of hair on its abdomen. The black abdomen of the carpenter bee is smooth and shiny. There are also two flies that you might mistake for bumblebees, but they only have one pair of wings and are smaller. They do not gather pollen, and are parasitic, feeding on other insects including bumblebees.
Believe it or not, there are nine species of bumblebees in the state of Texas alone, although only a few are found in north Texas. (For a list of bumblebee species check the following sites: www.texasbumblebees.com; www.inaturalist.org; www.bugguide.net). Unlike honeybees, the bumblebee has an annual life cycle. That means they’ve got to get right down to business because they’ve only got part of the year for their contribution to the species.
Bumblebee Life Cycle: Let’s start in the spring, when the females emerge from the ground, heavily laden with eggs. They’ve got two things on their mind: find some food, and establish the beginnings of a new hive. Their hives are normally in the ground, but might also be above ground in a mulch pile or something similar. These females are typically large, perhaps an inch and a half in length. You might notice them dropping to the ground over and over again in search of the perfect hive location.
Once she finds the right spot she lays some of her eggs, only those eggs which produce non-queen females. These females will become the workers. She then begins to create small honey pots within the hive. The honey will feed her during inclement weather, and will provide nourishment to the newly hatched worker bees until they are ready to fly. This process will continue throughout the summer, more and more worker bees and many honey pots to feed the newborn. The only potential threat is another species of bumblebee that might inhabit the hive as a parasitic bee, sometimes referred to as cuckoo bumblebees. Parasitic queen bumblebees will monopolize the hive, sometimes killing the resident queen. She will lay her own worker eggs and the original workers will raise them. Parasitic queens die soon after laying the eggs, for that is their only purpose in the world of bumblebees.
Toward the end of the season, sometime during the summer, the queen begins to lay eggs that produce males and queens. The males have only one purpose. Initially, they stay in the hive and are cared for by the worker bees. Once mature, they leave the hive and lay in wait for the emerging queens. It is common for multiple males to fertilize the emerging queens. When their job is done, and the food dries up, the males die. The original queen also dies at the end of the season. The new queens find a suitable place to spend the winter, and burrow down into the earth until conditions are right to emerge, find food, and establish a hive of their own the following year.
Status: You might wonder why we don’t hear more about bumblebees since they produce honey. Unlike honeybees, bumblebee hives are small. A bumblebee hive might have a couple hundred bees, but honeybee hives will contain thousands of bees. For that reason it is impractical to use bumblebees for massive production of honey. However, just as honeybees were brought to the states for pollination, bumblebees are being used in parts of Europe in greenhouses where the application is much more practical. Unfortunately some of those bees have found ways to escape the confines of the greenhouse, visit native plants, and then return to the hive with parasites. Some of these hives have come back to the states infected, creating colony collapse like that seen with some honeybee hives. The recent decline in bumblebees is creating renewed interest in their purpose, well-being, and future.
Summary: If you would like to know more about bumblebees you could start with the websites already mentioned. If you would like to help monitor the status of bumblebees in your area, contact Michael Warriner: Michael.warriner@tpwd.state.tx.us