Critter Catalog

Diversity

Bee-flies are insects in the genus Bombylius. This genus is made up of 335 species in 3 main groups. Bee-flies are mimics of bumblebees and other bees. Larvae are parasites that eat the eggs, larvae, and stored pollen of bees that live alone. Bee-flies are important pollinators. (Evenhuis and Greathead, 1999; "Genus Bombylius", 2012; Roskov, et al., 2020)

What do they look like?

Bee-flies are a genus that mimics bees, such as those in the genus of bumblebees. Like bumblebees, they are very hairy with colors ranging from black to orange. The hairs are often a lighter color than the body, except one subspecies that is covered with black hair. Unlike bumblebees, bee-flies have a long proboscis, four long legs, short antennae, and two wings. They do not have a stinger. They are medium-sized, but subspecies can be 8-16 mm long. The females of some subspecies are larger than the males. Larvae look like grubs. (Kastinger and Weber, 2001; Moisset, 2020)

• Other Physical Features
• ectothermic
• bilateral symmetry

• Sexual Dimorphism
• female larger

Where do they live?

Bee-flies are found nearly worldwide. There are about 280 species living in the United States alone! Large bee-flies are the most common species of the genus. They are found across the northern hemisphere. (Evenhuis and Greathead, 1999)

• Biogeographic Regions
• nearctic
• palearctic
• oriental
• ethiopian
• neotropical

What kind of habitat do they need?

Bee-flies are found in warm regions where flowering plants live. They can be seen on the ground, near flowers, and in bushes during the day. At night, they shelter in the crowns of trees. (Kastinger and Weber, 2001)

• These animals are found in the following types of habitat
• temperate
• terrestrial

• Terrestrial Biomes
• savanna or grassland
• forest

How do they grow?

Eggs are laid one at a time at the openings of solitary bee nests. Once they hatch, the larvae look for stored pollen, bee eggs, and bee larvae to eat. Once the larvae are fully grown, they go through metamorphosis. Adults stay in the bee nest until the next spring. (Kastinger and Weber, 2001)

• Development - Life Cycle
• metamorphosis

How do they reproduce?

Bee-flies mate and lay eggs during the spring to early summer. After mating, they seek out the nests of solitary bees to lay eggs. Once a nest has been found, the female hovers over the entrance and drops an individual egg. This process repeats. The eggs hatch, feed, pupate, then wait for the next spring to arrive. The larvae are parasitic. (Kastinger and Weber, 2001; Riley, 1881)

• Key Reproductive Features
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
  • internal
• oviparous

No information about parental involvement for this genus was found. (Kastinger and Weber, 2001)

• Parental Investment
• no parental involvement

How long do they live?

Not much is known about how long bee-flies live. They move too much and too quickly to be tracked. Adults appear two weeks before the earliest laid eggs do, so they must live at least two weeks. Bee-flies are found during spring to early summer. (Evenhuis and Greathead, 1999)

How do they behave?

Bee-flies are a genus of solitary flies. They make a buzzing sound when flying, are very fast flyers, and are able to hover in mid-air. (Kastinger and Weber, 2001)

Members of the genus are most active during the day when the weather is sunny and warm. They are typically found on the ground and flying in forests and bushes. When the weather is cloudy, bee-flies will sit on the ground in an attempt to warm themselves. If the sun reappears, the bee-flies will start to fly again. At night, they avoid the ground and bushes, as they seem to hide in the crowns of trees. (Kastinger and Weber, 2001)

• Key Behaviors
• flies
• diurnal
• motile
• nomadic
• solitary

How do they communicate with each other?

Bee-flies use the sense of sight, touch, sound, and chemical receptors to get information and communicate. (Kastinger and Weber, 2001; Moisset, 2020)

• Perception Channels
• visual
• tactile
• acoustic
• chemical

What do they eat?

Adults mostly eat nectar. Pollen has been found inside of bee-flies, but they haven't been observed eating it on purpose. Larvae are parasites that eat the eggs, larvae, and stored pollen of bees. (Kastinger and Weber, 2001; Moisset, 2020)

• Primary Diet
• herbivore
  • nectarivore

What eats them and how do they avoid being eaten?

Bee-flies are mimics of bumblebees (Bombus species). ("Genus Bombylius", 2012; Kastinger and Weber, 2001)

• These animal colors help protect them
• mimic

• Known Predators

  • Western Kingbirds (Tyrannus verticalis)

What roles do they have in the ecosystem?

Adults pollinate many different kinds of flowers. Larvae are parasites that eat bee eggs and larvae. The larvae of some species eat the eggs and larvae of locusts, fly pupa, and caterpillars. (Evenhuis and Greathead, 1999; "Genus Bombylius", 2012; Riley, 1881)

• Ecosystem Impact
• pollinates
• parasite

Do they cause problems?

There are no known adverse effects of bee-flies on humans. (Kastinger and Weber, 2001)

How do they interact with us?

Bee-flies are important pollinators. They visit purple, violet, blue, and white flowers more often than other colors. Lungwort, purple gromwell, common bugloss, and European stickseed are commonly visited plants. (Kastinger and Weber, 2001)

• Ways that people benefit from these animals:
• pollinates crops

Are they endangered?

No special status.

• IUCN Red List [Link]

  Not Evaluated

Contributors

Deena Hauze (author), Animal Diversity Web Staff.

References

2012. "Genus Bombylius" (On-line). Bug Guide. Accessed May 08, 2020 at https://bugguide.net/node/view/9490#synonyms.

Beal, F. 1912. Food of our more important flycatchers. U.S. Department of Agriculture, Biological Survey Bulletin, 44.

Evenhuis, N., D. Greathead. 1999. World Catalog of Bee Flies (Diptera: Bombyliidae). Leiden: Backhuys Publishers. Accessed May 08, 2020 at http://hbs.bishopmuseum.org/bombcat/.

Kastinger, C., A. Weber. 2001. Bee-flies (Bombylius spp., Bombyliidae, Diptera) and the pollination of flowers. Flora, 196: 3-25.

Moisset, B. 2020. "Bee Flies (Bombylius spp.)" (On-line). U.S. FOREST SERVICE. Accessed May 08, 2020 at https://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/bee_flies.shtml.

Riley, . 1881. The American Naturalist. Larval Habits of Bee-Flies, 15(6): 438-447.

Roskov, Y., G. Ower, T. Orrell, D. Nicolson, N. Bailly, P. Kirk, T. Bourgoin, R. DeWalt, W. Decock, E. van Nieukerken, L. Penev. 2020. "Species 2000 & ITIS Catalogue of Life" (On-line). Accessed May 09, 2020 at www.catalogueoflife.org/col.