Wednesday, April 21, 2010

Ellen Rathbone: Bee Watching

Anyone who has read my nature blog lately has probably noticed my current preoccupation with bees. This is likely due to several things, such as the fact that the most visible and approachable wildlife around my yard right now is the bees busily visiting my giant pussy willow shrub, which is blooming with great profusion thanks to the recent heatwave. A variety of insects are obsessed with this shrub, for it is one of the earliest flowering plants up here, and these newly awakened insects are in need of sustenance. QED. But my interest is in the bees, mostly, because native bees are generally given short shrift by people. If it isn’t a honey bee, then it’s not worth knowing. In some circles, this is considered “job security” for people the likes of me because it provides grease for the educational wheel. So, with this in mind, let’s take a look today at some of our native bees.

We will start with basics. Honey bees are not native. Honey bees were brought to this country over three hundred years ago as indentured servants: they made honey and we wanted it. Additionally, colonies of honey bees were established in (and later moved among) orchards and other crops, where their penchant for pollinating was exploited by the agriculture industry. This is all very well and good, but we also need to recognize that North America is home to several hundred species of native bees, most of which are solitary rather than colonial, and most of which are important pollinators in their own right, even if they are overlooked by the bulk of humanity.

The majority of native bees in New York State are solitary ground-nesters. In fact, these fuzzy little bundles of energy make up about 60% of all NY bees. That’s an impressive amount. I first became aware of these little bees just about a year ago when I stumbled upon a group nesting site in the dusty, sandy margin of the road while I was picking up trash. It was fascinating to watch as the bees flew in and out of their pencil-sized holes in the ground. Curious, I had to know more.

My investigations into the identity of those ground bees suggest two possibilities: mining bees (Adrena) or digger bees (Anthophora). The individual in the photo above (a visitor to my willow) has been identified as Adrena frigida. Nationally, there are something like 1200 species of Adrena; New York is home to 112 of these, which account for about 23% of all NY bee species.

Adrena are non-aggressive little bees, measuring a little over a centimeter in length, and are one of the first bees to emerge in the spring, foraging for pollen among early flowering plants like willows. As soon as there is pollen to be had, these bees head for the blooming larders, the females collecting pollen on the fuzzy hairs that cover their bodies. Later, they’ll remove the pollen and store this protein-rich food in the brood cells they build, one at a time, underground. Here they lay their eggs, one per cell, each cell stocked with enough food to see the larva through to adulthood. Unless…

Another early springtime bee I’ve seen around my shrub is a cleptoparasite from the genus Nomada. These little bees are hairless, making them look more like wasps than bees. While they may be gathering some pollen and nectar for food, they are not collecting it for their offspring. Nope, these little bees seek out the burrows of our friend Adrena and lay their eggs in Adrena’s nests, kind of like a cowbird laying her eggs in a robin’s nest. When the Nomada larvae hatch, they eat all the stored food, either starving the Adrena larvae or outright killing them. What emerges later in the season are not happy little Adrena bees, but new Nomada bees, and the cycle begins again.

It’s a bee eat bee world out there.

Although Adrena are solitary bees, they often nests in communal aggregations, like the one I saw last spring along the roadside. This is because good nesting ground is at a premium. Go outside and take a look around. How much bare ground do you see? Odds are that unless you live on a construction site it isn’t much. Most ground is covered with pavement, grassy lawns, fields or forest, depending on where you live. Therefore, when bare patches are found, these bees move in. Sandy slopes are likely to be peppered with many bee nests (upwards of 100 nests per square meter), each with a pencil-sized opening. If you sit and watch for a while, you’ll see the busy little females zipping in and out of the holes, bringing in pollen to fill the larder, laying eggs, or putting the final touches on a brood cell.

Why should the average New Yorker care about Adrena? Based on this article, you might think that all they do is pollinate willows. Well, willows only bloom in the spring; therefore, these bees visit other flowers as spring turns into summer and summer progresses towards fall. If you like apples, which are a major crop in New York State, then you must tip your hat to Adrena and our other native bees. Cherries are also popular with little Adrena and her solitary cousins.

Colony collapse had been in the news for a few years now – a mysterious disorder that had resulted in massive die-offs in honey bee populations. Scientists studying colony collapse are also interested on the effects it might have on populations of native bees. Native bees are also being looked at as possible replacements for honey bees in the agriculture pollination game. One of the big problems with using native bees is that they simply do not live in colonies composed of thousands of workers, like honey bees do. Bumble bees, our native social bee, may have a few hundred workers at most in a colony – not as conducive to industrial agriculture as the honey bee.

But native bees should not be discounted just because they are more individually oriented. In fact, many a home gardener should do everything possible to make his or her yard appealing to our native bees, many of whom are also facing a population decline. Native bees evolved with native vegetation. As people spread across the country, they brought non-native plants with them – from flowers to food crops. While native bees have adapted to many of these foreign foods, they still only thrive on the plants with which their species developed. So how can we help? By planting native plants and cutting down on non-native varieties.

So, head outside and take a seat in a nice sunny spot. Start watching for bees. See if you can make out more than one species. Are they patrolling the grass, maybe looking for a good nesting spot? Can you determine which plants are frequented by which bees? Are they visiting your flowers beds or your veg gardens? Perhaps they are enjoying a wee dram at your hummingbird feeder. Bee watching can be a lot of fun. Mark my word: bee watching will soon be the latest thing, right up there with butterfly and dragonfly watching.

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Ellen Rathbone is by her own admission a "certified nature nut." She began contributing to the Adirondack Almanack while living in Newcomb, when she was an environmental educator for the Adirondack Park Agency's Visitor Interpretive Centers for nearly ten years.

Ellen graduated from SUNY ESF in 1988 with a BS in forestry and biology and has worked as a naturalist in New York, New Jersey, and Vermont.

In 2010 her work took her to Michigan, where she currently resides and serves as Education Director of the Dahlem Conservancy just outside Jackson, Michigan.

She also writes her own blog about her Michigan adventures.





One Response

  1. Woodswalker says: