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Andrena Bees (Mining Bees) Rise in Early Spring

April 08, 2016 thebeeswaggle

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I was lucky enough to spot this lovely bee in my yard, perched on one of my beetle kill pine bee houses, yesterday morning!  It seemed early for bees to be up, and cold, but apparently, this little mining bee is in the habit of defeating the odds and flying at cooler temperatures!

Mining bees are part of a very large group of bees referred to as Andrena bees.  They all nest underground, and emerge either very early spring or even fall!  Some are so eager to emerge, snow is still on the ground! Scientists are baffled by the ability of these bees to fly at such low temperatures.

Bees need to be warm to fly, between 50 and 60 degrees Fahrenheit, and Andrenas can be seen at temperatures between 40 and 50 degrees Fahrenheit.  Andrenas have been seen in places like Alaska and Northern Canada!  Burr!!

It is unknown exactly how these bees can achieve  flight at such low temperatures, but I am willing to bet it has something to do with their flight muscles, and heat sequestering between segments, maybe similar to bumble bees.

The time they emerge often presents without blooms, which Adrenas must live off of their fat stores and find other ways to occupy their time.  Other ways include mating and finding good nesting sites!

Their choice for nesting sites is most often the ground, and more specifically, sandy or clay-like soil.  They look for discrete entrances with leaves or rocks surrounding the hole into their nest.

It may sometimes appear Andrenas are social bees because they may form aggregations of nests, or even share an entrance which leads to many nesting holes.  They are not, however, social, they are solitary bees.  These bees may produce one or even two generations of young in one season, depending on the species within this genera.  So, they are busy little pollinators, as is the case with all solitary bees.

Andrenas have been found to be important pollinators of blueberries, cranberries, apples, and some wild onions too (even better than honeybees too)!  If it blooms early spring, you can bet that these bees are frequenting those blooms!

They are typically generalists, meaning they visit many different flowers for nectar and pollen collections, but there are a few that are very dependent on a single plant’s flowers.

I wonder how many of you might spy an Andrena in your yard at this time when everything is just beginning to wake up. There are many different sizes and colors, so send some pictures, and maybe we can identify bees together!

Thank you for joining the movement!

Jess





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