Early Spring (and Late Winter) Bees

Over the past few days, on my walks in the woods, I’ve seen a number of little bees buzzing around just above the forest floor.  None of them have held still long enough for me to even attempt a photo, but luckily I met a few more cooperative ones last March, during my lunch break at work:

These are mining bees (Andrenidae: Andrena), which nest in burrows they dig in the ground.  In lawns their burrow entrances are conspicuous, surrounded by excavated sand that makes them look like little anthills, but the ones that nest in the woods seem to burrow under the leaf litter without producing any visible sign.

I got close enough to the little buzzing bees yesterday to see that some of them, instead of being pale and fuzzy, were mostly smooth and red, with some yellow markings on the abdomen.  Here is a similar one from last April:

This is a cuckoo bee (Apidae: Nomada ruficornis species group), which lays its eggs in the nests of mining bees.

Yesterday evening, as I was returning home from an afternoon tour of my local vernal pools, I came across this big uprooted butternut tree in a sunny sugar maple stand:

As I approached the roots, I saw that this vertical surface was buzzing with sweat bees (Halictidae) just as the (horizontal) ground surface was buzzing with mining bees in some places.  These, however, held still long enough for me to get a few shots.

They were Lasioglossum (Dialictus), like the ones I wrote about last year, but they were most likely not the same species, since this subgenus includes 200 or so species.  I suspect that the bees nesting in the root mass are specific to this microhabitat, or at least to vertical soil surfaces, and as soon as I saw these bees I remembered something USGS bee biologist Sam Droege had said in an email last year: “Another thing to keep your eyes on in the spring . . . is that I think there are a set of bees that specialize in nesting in upended root masses of windthrown trees . . .  I think it would be very interesting to do a survey of such.”  There was ample exposed soil in this sugar maple stand, because a herd of turkeys (which I met on my way in) had just been busy scratching away the leaf litter in search of food.  These bees showed no interest in the turkey-scoured areas, though no doubt some other bees will appreciate them.

I haven’t seen any of these bees feeding yet, but the available flowers in these woods now include skunk cabbage, beaked hazelnut, red maple, willow, chickweed, and hepatica.  I imagine tree sap is also an important food source in early spring.