World Bee Day....A Little "Bee"hind

World Bee Day happened the other day, May 20, and it caught me off guard. I had never heard of it, and hustled to make some social media posts for the Facebook groups I founded or administer. I will plan a bigger campaign of celebration next year, but for now....

In fairness, World Bee Day has not been in existence very long. The date honors the birthday of Anton Janša of Slovenia, a pioneer of modern beekeeping in the eighteenth century. The United Nations passed a resolution submitted by Slovenia in 2017 to so honor him. While beekeeping in the northern hemisphere applies only to honey bees in the genus Apis, the U.N. has chosen to use World Bee Day as an opportunity to acknowledge all bee species, the vast majority of which are solitary and not managed by human beings.

North American bees range from giant "large carpenter bees" like this one....

Given the plight of pollinators in general, and the threats to apiculture (beekeeping) from mites, pesticides, industrial-scale agriculture, habitat destruction, and climate....anomalies of increasing frequency, it is easy to be pessimistic and sorrowful on World Bee Day. However, there are signs of hope all around us.

....to tiny Perdita mining bees like this one.

More people are taking up apiculture as a hobby, for example. Even better, many homeowners and small-scale farmers are recognizing the importance of native bees and building simple housing for them in the shape of "bee condos." Now a small movement is building to advocate for allowing those bare patches of soil in your lawn and flowerbed to lie fallow. The overwhelming majority of solitary bees in North America nest in burrows they excavate in the ground. Sometimes many females will nest in close proximity, giving the illusion of a "hive" or a swarm. This is not the case, and unless you step on a bee in bare feet or forcibly grab one, it is not going to sting you. Different bee species prefer different textures of soil, from sandy to clayey.

Leafcutter bees, Megachile sp., using "bee block."

Among the many reasons to celebrate World Bee Day this year is the rediscovery of the world's largest bee, Wallace's Giant Resin bee, Megachile pluto, nesting in termite mounds in Indonesia. It is an important reminder that the natural world is resilient, to at least some degree, and that most species can persist even in unfavorable circumstances.

Female cactus bee, Diadasia sp., entering her burrow.

Colorado, where my wife and I live, ranks fifth in bee diversity in the USA, boasting at least 946 species from huge bumble bees to tiny mining bees in the genus Perdita. California (1,651), Arizona (1,182), New Mexico (991), and Utah (979) rank ahead of us. That makes for a lot of bee species that need conservation if we want to continue enjoying wildflowers and eating everything from blueberries to squash to almonds.

We can encourage bees by....

• landscaping with native trees, shrubs, herbs, and flowers.
• Erecting bee blocks as supplementary housing for solitary bees (and wasps) that normally nest in the dead trees we cut down and logs we haul off.
• Become "weed tolerant" of plants that volunteer in our yards, as long as they are not state-listed noxious weeds. Chances are they are native or naturalized wildflowers instead.
• Leave a few bare patches in the lawn (if you still insist on having a lawn) and flowerbeds so that ground-nesting bees have a place to call home.
• Advocate for changes to municipal and HOA codes and rules that currently discourage eco-friendly landscaping.

It goes without saying that eliminating pesticides and other chemicals from your yard and garden will greatly benefit all life, not just on your property but elsewhere, too, as pesticides drift on the wind and flow in runoff from rain and watering.

Female sweat bee, Agapostemon sp., living up to her name.

World Bee Day is behind us this year, but no worries. You can gear up now to celebrate National Pollinator Week next month, June 17-23, 2019. Tell me how you plan(t?) to respect that designated "holiday." Maybe you need to do what I should do, which is call my governor and ask why Colorado is not yet on the map for it....

Cuckoo bee, Nomada sp., leaving (left), small carpenter bee, Ceratina sp., arriving (right).

Don't Sweat 'em

During the heat of summer, we all perspire. Some insects find that bodily function irresistible. Among them are sweat bees, various flies, and even butterflies. It is believed that the salts, minerals, and other compounds in our sweat are necessary for these insects, and difficult to find elsewhere. While you might assume that any insect landing on you intends to bite or sting, rest assured these insects are harmless.

Female sweat bee, Halictus rubicundus

Solitary and semi-social bees in the family Halictidae are collectively known as "sweat bees" because of their habit of lapping up human sweat with their short "tongues." They may tickle at most, but if you smack one absent-mindedly, it may indeed sting if it is a female bee. Male bees lack stingers.

Two different sweat bees, both Lasioglossum species

Sweat bees come in a variety of sizes and colors, from miniscule brassy Lasioglossum species to brilliant metallic Agapostemon species (and related genera). Members of the genus Halictus are medium-sized and brown or blackish with white bands across the abdomen. Nearly all species nest in the soil, each female excavating her own burrow.

Female sweat bee, Agapostemon sp.

Compounding the problem of recognizing the different insects that seek out your sweat is the fact that many flies in the family Syrphidae are wrongly called "sweat bees" in casual and regional language. Syrphid flies are more properly called "flower flies" here in the U.S. and Canada, and "hover flies" in Europe.

Tiny Toxomerus syrphid flies are often mistaken for sweat bees

Like bees, they can be important pollinators of flowers, but it is in their youth that they are most beneficial. The larvae of many flower flies prey on aphids, which are major crop and garden pests. Thus, the more syrphid flies, the better, even if they do want to drink your perspiration.

Unidentified syrphid fly on my arm, lapping sweat

Plenty of other flies, mostly blow flies (family Calliphoridae), and flesh flies (family Sarcophagidae), will land on us, too. Even some tachinid flies (Tachinidae) will wander around on bare hands and arms. They may not all be there for moisture or salts.

Tachinid fly using me as a lookout post

Some of these flies may be males that are simply using us as convenient perches from which to defend their territory. They will periodically fly off to chase away competing males, or pursue passing females.

Some butterflies are well-known for requiring certain minerals to complete their life cycle. Usually, male butterflies congregate around mud puddles, puddles of urine or piles of scat left by mammals, or even rotting carcasses, where they obtain nutrients that they will pass to females during mating.

Hackberry Emperor butterfly getting salts from animal dung instead of sweat

Males with a higher mineral content are more desirable to females, though how this is determined remains something of a mystery. She puts the transferred chemicals to good use in producing her eggs.

Occasionally, some butterflies will use us as substitutes for their usual mineral resources. I once had a Hackberry Emperor butterfly land on my toe while I was sunbathing in a park in Cincinnati. I had another land right on my sunglasses in a different location in Ohio, but he viewed me as a convenient perch from which to defend his territory.

Female Lasioglossum sweat bee with tongue extended, lapping sweat

Most research into the attractiveness of human sweat to insects has been directed at blood-feeding insects such as mosquitoes and other biting flies. Consequently, there is relatively little known, and much assumed, about the fascination non-biting "bugs" have with our skin pore excretions. One thing scientists can agree on? Don't sweat the sweat bees.

Tiny female Lasioglossum sweat bee on my fingernail

Source: Gibb, Timothy. 2015. "Do Not Confuse Hover Flies with Sweat Bees," Purdue Plant & Pest Diagnostic Laboratory, Purdue Extension, Purdue University.

Unidentified tachinid fly grooming itself on my arm