A boon for bee flies at Borderlands Nursery & Seed

Guest blog

On a recent Saturday morning in August I had the opportunity to photograph insects at Borderlands Nursery & Seed. Previous visits to the nursery (during shopping excursions or butterfly counts) had always yielded a wealth of insects to observe. After chatting with Native Plant Program Director Francesa Claverie, she suggested I check a row of blooming San Pedro Daisy (Lasianthea podocephala) for insect activity, so I began there.

The American Southwest is a global hotspot for bee flies (Bombyliidae), important pollinators that are most diverse in arid habitats of the Old and New Worlds. The family's 4,800 or so species range in size from barely half a grain of rice to that of a bumble bee. Their name is derived from many of the hairier species appearing to mimic bees. They are frequently seen probing for nectar by walking on or hovering over blossoms. Occasionally groups of them can be seen congregating at puddles for moisture. Just in our southeast corner of Arizona, we have more than 220 species of bee flies, many of which, although large, attractively patterned and numerous, have not been formally described and given scientific names. Several of us (amateur entomologists) are developing a website for the bee flies of Southeastern Arizona. I can't say it will make them easy, but it will help you discover these attractive and valuable insects. (So stay tuned!)

A bee fly from the genus Thevenetimyia visits a San Pedro Daisy at Borderlands Nursery & Seed.

One variety of bee flies that has generally eluded me during the last 20 or so years I've been aware of them is the genus Thevenetimyia, which includes 24 species that live north of Mexico, and half a dozen or so can be found in the Patagonia area. Their very long legs, slender bodies, and long proboscis ("beak") give them a remarkably mosquito-like appearance, although, like all bee flies, they are totally harmless. Our local species, which are mostly monsoon fliers, may be smooth and shiny, or cloaked in a fine pile of black or gold, with smoky or patterned wings that aid with their identification. Photographs often show a dusting of pollen grains on various parts of their body.

Setting down my tripod at the first plant in the row of the greenhouse, I was astonished to see no less than six of the near-mythical Thevenetimyia probing the blossoms! Before taking any photos, and now experiencing the beginnings of a heat and bug-induced swoon, I walked the row of San Pedro Daisies, estimating perhaps 150 Thevenetimyia of two different species—truly the mother lode. Mixed in with them were five or six species of more common bee flies.

Another species of Thevenetimyia enjoys the abundance of flowers.

Here and there on the disc flowers were the curiously charming, tiny yellow Poecilognathus, one of our smallest bee flies and, at 3 millimeters, unlikely to be noticed unless you're looking for them. Also present was Paravilla consul, a member of a large and poorly understood genus of often very similar flies that have a conical face, dusky wing bases and, in the case of this species, often distinctive convict barring on the abdomen.

A tiny yellow Poecilognathus blends in with its surroundings.

Indeed, photographic opportunities were profuse. The next row of plants, a dense stand of Prairie Acacia (Acaciella angustissima) in full bloom, was being visited by wasps and bees of dozens of species and every conceivable size and pattern, all intent on gathering pollen and nectar, and completely ignoring me as I stuck my head into the foliage for a better look at some choice individual. Further over, a row of mistflower (Conoclinium) was partly bloomed out but a couple dozen Queens and a variety of other butterflies fluttered at its tiny blossoms.

The Paravilla consul resembles a bee at first glance.

As the temperature crept toward 100 degrees and the light breeze hindered macro photography, I slowly moved my tripod and a folding chair down the rows of plants, just enjoying the bee flies, the butterflies, and the other insects they attracted and nourished. Despite having been a habitat gardener for more than two decades, I was deeply impressed by the numbers and diversity of insects present, and pleased to know that these forbs and shrubs, their offspring, and the dozens of other plants raised at Borderlands Nursery & Seed would enrich gardens and encourage pollinators all over the Southwest.