May 11th, 2006
the bee’s knees
With cherry and pear trees now in flower here at the farm, I’ve been seeing plenty of Bumblebee activity over the past few days. For some time now, I’ve been trying to photograph as many Bumblebees as I can in order to get to know the various species a little better. It seems that many people are surprised to find that there is more than one kind of Bumblebee — those fuzzy, round-bodied, yellow and black bees that bump and buzz around through the flowers. In fact, there are quite a number of species that belong to the genus Bombus. I think there are something like 45 species of Bombus found in North America (but better not quote me on that as it could be a few more). As well, there are another half-dozen or so species belonging to the genus Psithyrus, a group of bees which do not collect pollen — well, more about them a little further on.
I’m chiefly interested in Bombus bees, or more specifically, those Bumblebees that collect pollen. When you really begin looking at them, you’ll soon find that there’s a great deal of variation in their size, body shape, wing shape, and coloration – as can be seen in the above photo of what I believe is B. ternarius, and the photo below, which is probably B. impatiens. There’s a lot of physical difference between females and males, with queens usually being considerably larger. And there’s also considerable difference in their temperament, with some being very docile, while others are — shall we say — a little on the testy side (definitely don’t push their buttons or you could be sorry). I’ve never been stung while photographing Bumblebees, but have been chased by a few large, predominantly yellow bees which I’m quite sure were probably B. fervidus, which has a reputation for being rather aggressive (”The Natural History of Bumblebees” by Carol A. Kearns and James D. Thomson – p59). Offhand, I can’t remember if I’ve got any good B. fervidus photos, but if not, there’s probably a good reason for the lack. (-:
Bombus bees may be distinguished from the above-mentioned Psithyrus bees by their anatomy (should you wish to get close enough to see). Bombus bees collect pollen and have hind legs which are formed in such a way that pollen can be packed into wide or concave surfaces which are usually surrounded by stiff hairs. This pollen collecting area of the leg is referred to as the corbicula. The above photo gives some idea of the shape of the leg if you examine the small bit of pollen that has been collected and is adhering to the left hind leg. When the legs are more fully loaded, the pollen will be quite conspicuous, as in the next photo. Bombus bees also have a fuzzy layer of hair on both the upper and lower sides of the abdomen. Psithyrus bees differ from Bombus as they do not collect pollen and, in fact, are “social parasites” of the Bombus bees. Psithyrus females kill a resident Bombus queen and deposit their own eggs in her colony. The Bombus workers then feed the usurper and her brood. As Psithyrus do not collect pollen, their hind legs do not have corbiculae. Their abdomens lack hair and have a thick, shiny cuticle which is usually visible if you’re close enough to take a look. This type of abdomen makes them better equipped when attacking and stinging the less armor-plated Bombus bees.
Identifying bees seems a rather difficult business (at least to me) – probably made all the more difficult by the fact that I don’t actually collect the bees, but try to do IDs based on photos. A lot of bee photos that I’ve seen in online collections or in book plates, are of dead bees. Their coloration is usually very poor and the specimens often so desiccated that it’s hard to make good comparisons. It would also probably be better if I examined bees “in hand”, but that’s not really possible unless I capture and chill bees in the refrigerator (something I’ve rarely done). However, I’ve recently found a pretty good online bee identification guide on the Discover Life website. It seems to work quite well for IDing bees from good photographs. I’ll try to post more on Bumblebees, and many other bees as well, as I begin shooting more photos this season.
Tags: Bumblebee, Bombus ternarius, Bombus impatiens, Bombus fervidus