Friday, October 5, 2012

Bee Gone until Spring: Itztlacoliuhqui Returns

Two well worn Leaf-cutter Bees making sunflower seeds as the Equinox looms
Alas, Itztlacoliuhqui has awakened and the season of hard frosts has begun. It seems peevish to complain after what seemed a relatively long and mild Autumn, but was it? Determining the First Fall Frost isn't as easy as it sounds given the variable nature of climate, the movement of winds, and the effects of concrete and buildings. Officially, frost is when the air drops to 0 degrees Celsius at 150 cm above the ground as measured in a standardized instrument shelter. These weather stations tend to be located at airports or other official facilities. The Alberta Agriculture and Rural Development site gives the average First Fall Frost Date for three such facilities around Edmonton: the International Airport (Sept 10) located in the open fields well to the south of town, the Canadian Forces Namao Base downtown (21 Sept), and Stony Plain (21 Sept) well to the west. Another commonly given date is for Edmonton's FFF is 23 September, just after the Autumnal Equinox.
Leaf-cutters use their hairy bellies to hold pollen, something sunflowers must appreciate
The Home Bug Garden isn't particularly close to any of the official sites and doesn't have an official weather station of its own. What I use are a thermometer on the porch railing, the garage roof, and the crop plants originating in South America to determine First Fall Frost and First Killing Frost. This year the first frosty roof was 16 September (thermometer < 1 C). The average for the last 8 years is 12 September (range 28 Aug to 23 Sept). The beans, tomatoes, and peppers died on the morning of 4 October (-4 C). The average for the Killing Frost for the last 8 years is 2 October (range 17 Sept to 15 Oct). I guess a week or two after the Equinox is the best I can expect.
Scarlet Runners, tomatoes and peppers know when Itztlacoliuhqui has returned
So, this Autumn hasn't been unusually long. I guess it just seemed that way by way of memories of previous less pleasant Septembers. Another influence has been that the flowers have been essentially bee-free for two weeks. Flowers with no bees seems wrong, and the few honeybees to be found don't make it quite right. I don't begrudge honey bees the bit of honey they may make, after all they've just been robbed of their summer's savings and have nothing but sugar water to look forward to until spring. But where are the native bees?
Where have all the bees gone? Gone to graveyards every one?
Sadly, most bees have a life that is nasty, brutish, and short. Well, short at least. It's hard to think of days wallowing in flowers as being all that brutish and they do seem to enjoy their work. Bees never seem bored, at least not until late in the season. Then they do tend to bludge a bit, but by then they are old and worn as the tattered wings in the pictures of the Leaf Cutter Bees (Megachile sp.) above attest. Most of our native bees are active for but one season. They spend the winter in an immature stage (typically a pupa) in a nest, emerge from their nest holes in the spring or summer, make plants set seed and new bees grow for as long as they can, and then die.
Cleptoparasite Coelioxys - a bad bee if you are a Megachile
Not all of their nests will produce new bees in the spring, or at least not the bees that they hoped. Some will freeze, some will dry out, some will be dug up, some will turn into fungi or bacteria, and some will transform into different kinds of bees or wasps or flies or other kinds of parasitic insects. Our leaf-cutter bees have to run the gauntlet of all of these woes, but perhaps the most insidious club-strike is the robbing and murder by Cuckoo Leaf-cutter Bees in the genus Coelioxys. These bees invade a nest of a Megachile (a close relative), deposit their own egg, and their larva then eats the provisions collected by the Megachile and kill her young. As fascinating as this 'theft parasitism' (kleptoparasitism) may be, I'm sure that even Aesops would have found it difficult to draw a moral lesson. 
Spring and this Megachile wants what the Bombus borealis is monopolizing
Oh well, at least some bees build their own bed of roses and some get to see both Fall and Spring. Bumble bees (Bombus spp.) are an exception to the work hard and die in the Fall of beedom. Worker and drone bumble bees are all pretty much at permanent rest now, but next year's queens are huddled down in an old mouse burrow or some other refuge waiting for next spring. Unless someone accidentally digs one up while gardening, these queens will emerge as early as warmth permits and start new colonies in May. A bit later the Megachile that survived will emerge and join the growing legions of busy pollinators, and of course, their parasites and predators. And Itztlacoliuhqui will go to sleep until around the next Equinox.
Mystery male parasitoid enjoys the summer's bounty

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