March 28, 2024: wild bees emerged in Chicago today! 53F and sunny, so I headed out to Sidney Yates Flatwoods. It was there that I met two bees: one new friend Andrena erigeniae and one old friend Colletes inaequalis.
Andrena erigeniae, the spring beauty bee
As I looked across the forest floor, I noticed splashes of spring beauty throughout the leaf litter and around the base of trees. Spring beauty (Claytonia virginica) is one of the earliest of our flora, and some of the first food for bees in the understory. That’s where I’d look to find my target bee of the day.
It didn’t take long before I met up with the bee I was searching for. I spotted male Andrena erigeniae cruising over the ground and perching on warm shards of bark and on sedges in the sun. They paused frequently, providing me with generous looks, and I noted immediately how they glistened. Their wings were opalescent, reflecting the light of a rainbow. If I squinted, I could convince myself their bodies were not totally black but dark gray, and metallic. I also noted how their thick brush of hairs on their face screamed Tom Selleck. Once I saw it, I couldn’t un-see it.
The bee and the flower go together—spring beauty and the spring beauty bee. Floppy leaves present a modest offering of pollen and nectar. Each flower has five petals, with pink stripes guiding an incoming visitor towards the center of the flower. The anthers of spring beauty present hot pink pollen, and this pollen happens to be the favorite of female Andrena erigeniae.
This bee’s specialized diet is somewhat of a field mark—find spring beauty in early spring woods, and you will almost certainly find the spring beauty bee. It is this sort of holistic approach to bee watching, one that that incorporates both bee appearance and habitat preferences, that we advocate for when going bee watching.
Males drink nectar and patrol patches of spring beauty to ward off intruders in his territory. Since females are fond of gathering pollen from these plants, it can pay to patrol flowers in wait of females. That being said, males seemed to frequently get distracted, so who knows how effective this strategy might be.
A male cruised along a south-facing slope. Then, a scuffle! He landed on top of a female, but she shoved him away, uninterested in his advances. She landed at the base of a red oak, groomed her antennae, and gathered herself. She was larger and her thorax hairs were brown, and when the sun caught her face, her coppery foveae shone. She lifted off, and the male, just a few feet away, also lifted off. She flew to a nearby spring beauty, sipped nectar, and then vacated the area.
My eyes often drifted upwards into the canopy. I have to remind myself often to look up instead of just out and down. In particular, wind-pollinated trees like oaks can produce significant amounts of pollen, and yet the value of this pollen to early spring bees in eastern forests has been often overlooked since the flowers do not produce nectar. Some male bees like Andrena tridens like to patrol up and down trees, so giving sun-lit bark a glance up and down can be productive in spring forests. However, I didn’t note any activity in the canopy today.
There wasn’t much else blooming in the understory (besides a handful of Cardamine douglasii and Cardamine concatenata) so I get why they use Claytonia. When you’re the first bee out, you can’t be too picky.
Cellophane bees in Chicago
I also checked the eroding bluffs above the river and saw small sand-colored insects zipping above the ground. I would know them anywhere: male cellophane bees (Colletes inaequalis)! They were on high alert for the scent of a female. On the face of the bank, I saw small emergence holes characteristic of a nesting aggregation. I only saw males, so I’ll have to return in a few days to catch up with females and perhaps spot mating action.
Cellophane bees were not as common as I was expecting throughout the preserve. In New England, where I am most familiar with this species, a suitable aggregation might contain several hundred to over a thousand bees. Today, I only saw a few dozen at this one particular slope, despite most of the banks appearing to be fairly well draining soil and south facing. Perhaps I was too early, or perhaps Chicago’s generally clayey soils put a damper on local population sizes.
