My interest in the diversity of bees

Updated: Nov 27, 2020

A yellow-legged furrow bee, Halictus rubicundus, feeds from the tiny white flowers of a carrot plant.
Halictus rubicundus

My interest in the diversity of bees started when I noticed a striped insect land on a south-facing patch of bare dirt next to my front door and duck into a tiny hole. I had heard of "native bees" and I wondered whether this could be one, so I hunkered down with my cell phone on camera mode and watched. There were two other similar holes in the dirt a few inches away, and I got a few shots of the insects entering and leaving. I posted those to iNaturalist, where between the AI computer ID algorithm and a confirming ID from an expert entomologist, they were found to be Halictus rubicundus. Knowing their name gave me the key to finding more information about them and their fascinating life history. For example, depending on conditions (like the availability of food), their behavior can fall on a spectrum from being primitively social, living in a nest where one queen lays the eggs and the other females do other jobs, to solitary, where each female bee strikes out on her own and stocks her own nest.

I was hooked. I kept watching the patch of earth. Early in the morning of the next day, the holes seemed to be gone, but on closer inspection I could see that they were blocked by wads of dirt. By mid-morning, they were open again, with bees coming and going. That day I saw an insect with a red abdomen go into one of the Halictus nest holes and scratch around. It turned out to be another bee: a brood-parasitic (kleptoparasitic) Sphecodes, which is in the same family as Halictus but reproduces by laying its eggs in Halictus nests rather than by making its own nest and gathering its own pollen. In doing so, the Sphecodes larvae steal resources from Halictus, but at the same time, the Sphecodes population relies on there being enough Halictus or related bees around to create nests for the next generation of Sphecodes to parasitize.

A Sphecodes sp. bee in profile pose on a dandelion, showing its blood red abdomen.
Sphecodes sp.

I started watching a patch of nearby daisies, and the plot only thickened from there. I saw a beewolf (Philanthus), a wasp that hunts bees. I saw pale-colored crab spiders that blended in with the daisies' petals, only to lunge when an unsuspecting pollinator landed. I saw orbweavers' webs with bound-up bees that had noticeably shrunk an hour later. I found the occasional decapitated bee on a flower. It was clearly a dangerous and complicated world for "my" Halictus.

I also fell for every trick in nature's mimicry book. In addition to bumble bees, I saw what I was sure was a bumble bee, but learned from iNaturalist that it was actually a bee-mimicking Merodon fly. I saw what I thought was a honey bee, but it was an Eristalis "drone fly," named so because of its resemblance to honey bee drones. Among the brightly yellow-and-black-striped insects were both the yellowjackets and paper wasps I expected and a whole variety of hoverflies. iNaturalist set me straight, and soon enough I learned to spot the flies’ short, non-jointed antennae that are so different from bees' long, expressive ones. I was surprised one day when an expert reclassified what I'd thought was a Sphecodes observation as a non-parasitic bee that also happened to have a red abdomen and black head and thorax, a Lasioglossum ovaliceps. I did a double-take when a couple of weeks later I saw yet another hymenopteran with the same color pattern, this time a wasp, I believe an Astata.

Meanwhile, the Halictus kept going about their business as I watched. There were at least two other clusters of nest entrances in other dirt patches in my yard. Each nest entrance was perfectly blocked by the head of a wary guard bee, eyeing me (pic 2 here). Once in a while the head would disappear, a bee would barrel out, and a guard bee would immediately block the hole with its body again. When a female returned, her orange back legs would be caked thick with pollen. I also learned to recognize the slimmer males, each with a yellow patch on its face (on the clypeus). The males would buzz frantically around the nests, presumably trying to find females to mate with. At some point, I started noticing that there were males hanging out inside the nests, too, apparently a quirk of H. rubicundus.

Soon after I started to realize just how many types of bees were around, I got a copy of The Bees in Your Backyard and started surveying the neighborhood. For the first few weeks I was amazed to see a new genus of bees every day or two. "Long-horned" Melissodes, cute little bees whose males' antennae are as long as the rest of their bodies. Female Anthidium (wool-carder bees) shaving the hairs off silver ragwort leaves to use in constructing their nests, and male Anthidium driving away any other bees who dare approach their favored plants. Sleek Hylaeus, which carry their pollen internally and therefore don't have external scopa (pollen-carrying hairs). Tiny, shiny Lasioglossum and Ceratina, which I eventually learned to tell apart by shape, and the dark, shiny, but stouter Osmia. The brilliant green Agapostemon. The bumble bees (Bombus), with males sleeping in groups on bushes by the early evening. I was especially amazed that so many of the types of bees were kleptoparasites, like Sphecodes. Most of the parasitic species have much less hair, since they don't need them for collecting pollen, and many look armored. I saw thick-eyebrowed Andrena and their striking all-red parasites, the Nomada. Megachile leaf-cutter bees, occasionally carrying a piece of leaf, and their fearsome-looking sharp-tailed parasites, the Coelioxys, searching the ground for Megachile nest entrances. The cellophane bees, Colletes, and their parasites, the tank-like Epeolus.

An iridescent green bee with yellow legs and orange antennae on small white flowers.
Agapostemon - Metallic Green Bee

The threat of parasitism came from non-bees, too. Later in the summer I saw a brilliant green something-or-other skittering oddly near the Halictus nest aggregations, and eventually got a good enough photo for an expert on iNaturalist to identify it as a wasp in the family Chrysididae, which is a kleptoparasite of other wasps and bees. I also saw another kleptoparasitic wasp in my yard: an intimidating-looking member of tribe Nyssonini. I also spotted insects that are parasitoids, whose eggs are deposited on or in a still-living host. A block from my house, I saw a Leucospis wasp, which keeps its incredibly long ovipositor folded up along its back when it isn't aiming it downward to drill into solitary bee and wasp nests. On a bush abuzz with Lasioglossum bees, I saw a fly in the family Conopidae, which intercept and pierce their hosts in mid-flight to lay their eggs inside their hosts' bodies. I saw big flies in the genera Anthrax and Villa, of which some species both mimic bees and parasitize them.

I started to pay more attention to the plants the bees were landing on. The honey bees and Halictus appeared on all kinds of flowers, especially lavender for the honey bees. A steady stream of small, cylindrical Megachile angelarum fit themselves perfectly into the flowers of the broad-leaved sweet pea. A single enormous sunflower had enough pollen and/or nectar to occupy another Megachile for minutes while I tried to coax my cell phone camera into focusing well enough to count the teeth on its mandibles. I read in The Solitary Bees about the arms race of the bees and the flowering plants, in which their codependence and constant striving to conserve their own resources have led them to evolve into ever-greater varieties of shapes and behaviors.

A black leafcutter bee with white striped abdomen dangles upside down from a beautiful blue borage flower
Megachile sp. - Leafcutter Bee

With so much of human life now flattened, accessible only from behind a mask or a screen, it felt like a miracle to discover this byzantine world overlaid on the few square blocks where I now spent my time. Each fuzzy plant was an Anthidium territorial battleground, each crevice or patch of dirt or log or broken-off blackberry stem a potential nest site, each type of flower a way station for its own set of visitors. (Although not equally among flower species; the bees spurned many of the ornamental varieties.) It's now hard to imagine how I had spent years walking the stage of this great drama, unaware.

Through all of this, the iNaturalist community gave and gave, IDing my observations. I'd tapped into a reservoir of nerdy goodwill. They showed me what I could be if I kept learning. I'm lucky to have a wonderful job I could keep doing remotely, and a wonderful family, but this was my slice of time and brain space just for me, in invisible fellowship with all the other people who had discovered the delights of this six-legged plane of existence.

The outside world intruded when the wildfires filled the air with choking smoke, making it unsafe to walk around and make observations. I listened to the PolliNation podcast and heard about the pesticide overuse, habitat loss, invasive species, parasites, and infections that also threaten bees (and in the can-do spirit of that podcast, also about the creative ways people are dealing with those threats.)

I would like to take the joy that learning about bees has brought me and give back somehow, to the bees and the people who have helped me appreciate them, and also to bring this joy to people who haven't discovered it yet. I hope I can do some of this work with the WA Native Bee Society.

It's late fall now, and the Halictus nests are empty. The inseminated queens are hiding underground somewhere to wait out the winter. I hope they come back to my yard next spring.

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