Bee Flies

Order: Diptera (flies)

Family: Bombyliidae

How to identify:

Because bee flies look similar to bees, with yellow-and-black striped, roundish bodies, the two are often confused. Bee flies only have one pair of wings (instead of two) with their back wings modified into “halteres,” very small, club-like wings. Furthermore, their compound eyes are much larger than a bee’s, making up the majority of their head. 

Advanced Identification: The bee fly typically has a long, rigid proboscis, while the bee’s tongue can roll up when not in use (Moiset, n.d.). The wings have 3-4 posterior cells and the M1 vein ends at the wing tip (Borror & White, 1998). 

Ecology

Metamorphosis Type: Complete Metamorphosis

Geographic Range: Bee flies are found in the warmer climates of North America (Moiset, B., USDA, 2021).

Habitat: Bee flies require a warm habitat and are most active in the spring and summer. Bee flies can be found in grasslands and forests where flowers are available (Hauze, n.d. & Moiset, n.d.). 

Trophic Level: As larvae, they are parasitoids and eat the larvae of other egg and larval stage insects. As adults they are herbivores and eat the nectar of flowers (Moiset, n.d.).

Food: As adults bee flies use their long proboscis (straw-like projection from mouth) to reach deep into a flower for nectar.

Why should we care?

Human Uses: When people hear “pollination,” most people think “bees.” However, 70% of pollination is done by flies (Hooks, 2020)! Bee flies are considered more efficient pollinators than bees. The pollen sticks to a bee fly’s body every time they take nectar from the flower (Moiset, n.d.).

Conservation Status: Bombyliidae are not currently endangered and are considered in good standing (Hauze, n.d.). 

Did you know?

• Bee flies are known to seek out warm patches on the ground to rest and heat themselves up during overcast days (Hauze, n.d.)
• Bee flies lay their eggs at the nest entrance of fellow insects (e.g., beetles and bumble bees). They quickly hover over and fling their eggs into the desired nest without even needing to land! Once in the larval stage, the bee fly will feast on the eggs of that insect. Once you familiarize yourself with identifying bee flies, you can observe this behavior too! (Moiset, n.d. ; Arndt & Costa, 2010).
• Bee flies do not require rearing of any sort. Once a female lays her eggs in the spring, the offspring are on their own for survival (Hauze 2021).

Researcher’s Biography

Amalia Williams
Completed this research within Dr. Shelly Thomas’ Entomology course

Suggested Citation:

Williams, Amalia. (2021). Bee Flies. Rowan University Arboretum. https://arboretum.rowan.edu/learn/explore-insects/bee-flies/