Sunday, April 12, 2015

Floral Visitors 8

Upon getting a few hours outside, I was able to observe some pollinators in relative action! Despite the cold sunless weather, some bees and other insects have managed to make use of the brief periods of relatively "nice" conditions. My honeybee hives (I just split the hive about a week ago) seem busy with activity, Arbutus menziesii and Acer macrophyllum being in full flower (among others). I recently discovered what seems to be a fungal infection of Ascosphaera apis (chalkbrood) in at least one of the hives, for which there is no treatment, so I hope that all of the new plants coming into bloom will aid in the bees good nutrition and help them combat their malady!

Acer platanoides 'Crimson King'
About a dozen or so of these medium sized maple's grow in the parking lot of my workplace. Though the weather has been poor, I have still seen bumblebees and honeybees visiting the flowers. If the photo looks strange, it is because I had to remove a flowering piece to bring into the relative stillness of my car. It has been very windy lately, making photography of plants very difficult. I am regretful that I was unable to photograph a bee on these flowers, but knowing they were there is enough for me. There is a single tree of Acer platanoides near my house, though I have never witnessed much pollinator interest in it, besides a few small beetles. It is fairly isolated from any other flowering plants (while it is in flower), so this isn't too surprising.

Anemone coronaria
 A low scorer for pollinator attraction in my garden has now become useful as a shelter and a food source for spotted cucumber beetles (Diabrotica undecimpunctata). I do not mind the over-the-top splash of color these flowers bring to the garden (st nearly three inches across when fully open), and I am pleased that they can serve a further purpose at this time. They have never set seed for me, perhaps they are a sterile selected form or perhaps they do not receive adequate pollination services.

Ceanothus cuneatus
 Can you find the spider? Though the flowers of Ceanothus cuneatus across the landscape are going past their prime, they are still impactful visually and remain to attract a wide array of small pollinating insects. Upon accidentally bumping a branch, countless tiny flies or gnats were stirred and flew around until finally resettling on the flowers somewhere, hidden from view. The flowers certainly attract many different pollinators, the flowers are most attractive to the smallest types of pollinators. Larger bees like Megachile and Bombus will work the flowers when they are first opening, and many small beetles and flies will work the flowers over their bloom. But there are also many tiny bees that have shown interest, easily mistaken for small flies. The smallest bees are some of the hardest to photograph, requiring the camera to move very close, but they tend to be skittish and will quickly disappear if they feel threatened!

Mahonia aquifolium
This bee was not foraging at the time this picture was taken, but rather taking refuge. It was overcast, and possibly too cold for the bee to fly. Many bees, including honeybees, require a minimum temperature to fly. Some of the larger bees, like Bombus (bumblebees) are able to keep "warmed up" by vibrating their flight muscles. While smaller bees may not have this ability, they may be able to stay warm enough when they are in flight (think how you generate heat when you exercise) but cannot generate warmth when they land, so may end up stuck like this if they don't make it back to their nest in time. If the night is dry, they will warm up the following day and be on their way. The flowers do afford a minuscule amount of protection and warmth, absorbing and reflecting heat from the sun.

Prunus sp.
A late blooming plum-like (or possibly a cherry) tree in my yard is always the last of the fruit trees to bloom. It has in the past produced tiny bitter "mostly seed" cherry-like drupes, but the birds often get to them first. It could be that there are no other flowering fruit trees to cross pollinate with, or that it is itself a pollenizer, a tree planted specifically for the purpose of providing pollen to other fruit trees that require outcrossing. After removing a large blight-stricken branch last year, this tree appears to be flowering extremely well! My honeybee hives are situated less than twenty feet from the tree, and I have seen plenty of honeybees on it when the sun is out. Many flower flies (syrphids) have also been attracted to the flowers, even under less-than-perfect weather conditions.

Prunus sp.
Maybe it was due to the relatively low temperature at the time, but this bee let me take several dozen photos of it! I watched as it moved around slowly to imbibe nectar, perhaps curious as to what I was doing. Solitary bees differ from honeybees by a variety of reasons, with one notable characteristic in particular. Honeybees have specialized hairs on their hind legs called corbicula, but most often called "pollen baskets", that are open cavities surrounded by a "basket" of hairs to hold the pollen. Most solitary bees on the other hand have what are called scopa (see the picture), which consists of a dense patch of often branched hairs that hold the pollen. Honeybees use nectar to moisten the pollen and pack it into their corbicula, while most solitary bees store the pollen in its dry form in their scopa, which can be either on their legs or sometimes underneath their abdomen. This can help explain why solitary bees are more effective pollinators on a bee-per-bee basis of native plants and crops, the dry pollen in the scope will be more likely to land on a fertile stigma than will the wet packed pollen in a honeybees corbicula.

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