Bee Flies

Family Bombyliidae – Bee Flies

Bee fly Bombylius majorBee fly – Bombylius major

Bombylius species are by far the most numerous here in the American midwest. They are some of the earliest insects active in springtime – dandelions are some of their favorite flowers. Look for them along forest paths or disturbed areas with lots of flowers. They are very wary and demand a very low-angle, patient approach. If you blot out the sky, they will not hang around long since you look like a predator.

Bombyliidae is one of the largest families of Diptera, with over 5,000 valid species described worldwide. Their high diversity may be due to the parasitoid habit of the majority of their larvae. Adults feed on nectar and pollen, and are believed to be important pollinators of many plants, although few species have been studied in detail. Bee flies occur on all continents except Antarctica, however their highest diversities occur in semi-arid and arid environments (Hull, 1973).

Bee flies do not bite or sting and are completely harmless to humans and their pets.

The family includes a wide variety of morphological forms, such as the large Palirika marginicollis (Gray), with iridescent green-blue body scales recalling those found on the wings of a Morpho butterfly, and striking black and hyaline wings spanning 45mm; and the tiny, delicate, humpbacked yellow and black species of Glabellula Bezzi with hyaline wings and a body length about 3mm.

Bee Fly Lepidophora speicies

Scaly Bee Fly – Lepidophora lepidocera

I LOVE this fly. I’ve only seen it a few times. Now I’m out in the field photographing blister beetles, and along comes this Lepidophora, and decides he/she wants to bask in the sun on my shirt. Or my pants. Or my fingers or arms, you name it. What fun! Except some of those little bastard stable flies that like to bite your ankles decided to bite my ankles while I was holding my breath trying not to scare this absolutely strange and beautiful creature.

Bee fly, Poecilanthrax willistonii

Bee fly, Poecilanthrax willistonii

I found this lovely Bee Fly, Poecilanthrax willistonii, meandering about near newspaper rock at Canyonlands National Park in Utah. Insects in the western deserts seem much more wary and hyper than those in the middle west. Chasing these critters is hard work, especially under a hot sun. Indeed, a day of hard core photographing bugs is a great workout incorporating weight lifting, tai chi, patience, and maintaining awkward body postures for minutes at a time.

Bee Fly, Aldrichia species

This lovely, black-bodied Aldrichia species bee fly was found in deciduous forest outside Chicago. Bee flies are stout-bodied flying insects said to resemble bees, but there are syrphid flies and robber flies that do a much better job. Many bee flies have elongated mouthparts that form a conspicuous beak, used for sucking nectar long-distance while hovering over flowers.

Bee Fly Paravilla californica

Bee Fly Paravilla californica

Also found at newspaper rock in Canyonlands National Park in Utah. These charming creatures have been around for about 140 million years. The Bombyliidae are a large family of flies comprising hundreds of genera, but the lifecycles of most species are known poorly, or not at all. They range in size from very small (2 mm in length) to very large for flies (wingspan of some 40 mm). When at rest, many species hold their wings at a characteristic “swept back” angle reminiscent of our best fighter jets. Adults generally feed on nectar and pollen, some being important pollinators, often with spectacularly long probosces adapted to plants such as Lapeirousia species with very long, narrow floral tubes. Unlike butterflies, bee flies cannot retract their proboscis.

bee fly, Antrax species

Bee Fly, Anthrax complex

This tiny bee fly was intent of vacuuming up salt from my skin. It is about only 4mm long. This species has some of the most elaborate wing markings in the family, and is quite rare around Chicago. “Rare” is this instance meaning “will hold still long enough to snap a picture.”

Bee fly, Villa species

Bee fly, Villa species

I most often see bee flies hovering around flowers, or if resting on the ground, on bare soil. They are extremely wary and difficult to approach. No doubt their large compound eyes give them good vision, plus they have that air-motion sensing mechanism that helps the ordinary house fly avoid the swatter. Adult bee flies drink nectar, but the larvae are parasites of beetle larvae as well as the brood of solitary wasps and bees, the hole or burrow-nesting insects. I’ve often seen female Bombylius sitting in very loose soil, vibrating their butts like mad, so that the dirt is actually thrown outwards (below). They are laying eggs, which takes advantage of soil-inhabiting larvae of Coleoptera, Hymenoptera, Lepidoptera, and other flies, slowly devouring the host internally before actually killing it. A few are endoparasites, predators (esp. on grasshopper eggs), or kleptoparasites; stealing nectar/pollen from other insect’s nests. One wonders if their neighbors question the morality of these practices.

Bombylius sandly butt-tornado

Bombylius laying eggs via butt-tornado


Tree Encyclopedia / North American Insects & Spiders is dedicated to providing scientific and educational resources for our users through use of large macro photographs of flora and fauna.