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Monday, March 13, 2017

Bumble Bees: Panda Bears of the Insect World

The impatient bumble bee (Bombus impatiens)
the most common bumble bee in the Eastern US
© Beatriz Moisset

Most people hate or fear insects with just a few exceptions. Bumble bees have enough charisma to be loved, at least by children. You find children’s books, toys, and Halloween costumes about bumble bees. Perhaps what makes them acceptable is their fuzzy roundish appearance reminiscent of a tiny bear. This positive image is reinforced by their cheerful buzzing sound and their penchant to visit flowers. This is one insect whichpeople find easy to accept in a wildlife garden.

We all have a mental image of a striped black and yellow furry insect going from flower to flower. And we are all familiar with their humming sound, much celebrated in Rimsky-Korsakov’s Flight of the Bumble Bee. It is probably this sound that earned them the name of “humble bee,” with which they are sometimes known in England, from Middle Dutch “hommel” or Old High German, “humbal.”

There isn’t just one kind of bumble bee, but many. In fact forty-eight species live in the United States. Their basic pattern of black and yellow varies quite a bit. The more colorful ones sport orange-and-yellow or whitish-yellow stripes contrasting against the dark background. I am only familiar with a few of those that live in the Eastern United States, and I confess that I have difficulty telling some of them apart. That is not entirely my fault. Certain species of bumble bees are mimics of each other. This seems to be beneficial to them because hungry birds need to learn the unpleasant lesson of being stung only once and avoid all bumble bees with similar coloration.

Tricolored bumble bee (Bombus ternarius)
Several species share a similar pattern
© Beatriz Moisset
Bumble bees are important members of the wildlife fauna of a garden and they are fun to watch. They, along with other bees, pollinate flowers. Some are valued enough by farmers that a small industry of bumble bee nest boxes is growing steadily. They are valued by green-house tomato growers, in particular. Nobody else, not even honey bees, those workhorses of agricultural pollination, can do a better job at pollinating tomatoes. Moreover, they can live happily inside green houses with minimal care.

Tomatoes, and also blueberries and azaleas, make it hard for pollinators to reach the pollen. Their anthers, the flower part that holds the pollen, don’t split open exposing the pollen and giving flower visitors easy access to it. Instead, they keep their treasure encased with only a small opening at their tips through which the tiny grains can escape if handled properly. Bumble bees are pros at this task. They cling to the flower and give it a skillful shake by shivering their entire little bodies emitting a sound in middle-C, just the right kind of vibration to knock off the pollen grains and send them flying. Most of them land on the hairy bumble bee. The sound is unmistakable, even for somebody as musically challenged as me and cannot be mistaken by the buzzing sound of flying. You will recognize this sound next time you watch bumble bees at work in your tomato garden. You can also watch thevideo. This process is usually referred to as “buzz pollination”. I prefer to call it the “salt shaker technique.”

Like all bees, the females have stingers they may use in self defense, although they are not inclined to do so unless severely molested or if their nests are under threat. When they are collecting pollen or nectar at flowers, one can even take advantage of their good nature by petting them. I have had fun doing this many times. All the annoyed busy insect does is stretch one leg like trying to push your finger away. If it gets really irritated it will stretch two legs or more; then you can almost hear it yelling “quit it, enough already!”

Petting or pestering a bumble bee
© Beatriz Moisset
Well, I don’t recommend that you or your children try this. Don’t blame me if anything happens. A friend of mine takes advantage of the fact that males don’t sting. Sometimes she demonstrates bumble bee-petting to children but only with males. The best time is the early morning since males spend the night on flowers, unlike females who sleep inside their nests underground. They are sluggish at that time because of the morning chill and because they are just waking up. So, if you insist on trying, remember that.
This mason bee (Osmia cornifrons)
illustrates the tongue’s length of some bees
© Beatriz Moisset

Bumble bees along with some relatives, honey bees and carpenter bees, and also a few members of other families, leaf cutter bees, are called long-tongued bees. Their mouth parts are fairly long when compared to that of other bees such as andrenids and colletids which are called short-tongued bees. I wish I had a photo of a bumble bee sticking out its tongue. But I can show you a mason bee, Osmia, at the entrance of its nest with its impressive proboscis fully deployed. It is easy to see how such bees can take advantage of long-throated flowers or those with a spur.

Two spotted bumble bee (Bombus bimaculatus) on beebalm
© Beatriz Moisset
Despite belonging to the “long-tongued” bee category, some bumble bees deserve this title more than others. One of the truly long-tongued ones is the two-spotted bumble bee (Bombus bimaculatus). It can be seen drinking nectar from flowers such as bee balm, Monarda, unlike some cheaters like carpenter bees. The latter takes a shortcut by slashing the base of the flower and reaching its goal without entering the flower the “legitimate” way.

Bumble bee visiting jewelweed
© Beatriz Moisset
 It is also interesting to see some bumble bees visiting jewelweed (Impatiens capensis) flowers. They plunge their plump, little bodies into the flower, fitting inside like a finger in a glove. Even so the nectar is some distance from the entrance, at the end of the spur; so the bumble bee needs to stretch its tongue all the way. It is such an easy task for this flower visitor that it is in and out in the blink of an eye, having drained the stored nectar before the photographer has had enough time to snap a shot. They show similar behavior whenvisiting  Penstemon or beardtongue.
The interesting stories about bumble bees don’t end here. I will save others for later. Stay tuned for the next installments.

Bumble Bees: It is a Jungle out There
The Life Cycle of a Bumble Bee and its Colony
Brainy Bumble Bees
Bumble Bees in the Native Plant Garden
Bumble Bee Impersonators

© 2013, Beatriz Moisset. First published in Beautiful Wildlife Garden, 2013