The Many Roles of Bee Flies in the Sonoran Desert: From Predators to Pollinators

Bee flies are an essential part of the pollinator garden in Arizona, serving a crucial role in pollination and as predators of other insects.

Physiologically, bee flies have a distinctive appearance that sets them apart from other flies. They are covered in long, dense hairs that give them a fuzzy appearance. Their wings are clear and veined, and their eyes are large and often brightly colored. They have long, slender legs and a distinctive proboscis that they use to feed on nectar from flowers.

And adult bee flies are expert fliers, able to hover in mid-air and make lightning fast changes in direction.

As adults, bee flies feed on nectar and pollen from flowers, serving as important pollinators in the garden. Unlike other pollinators, bee flies do not have specialized structures for collecting and carrying pollen, such as pollen baskets or hairs. Instead, they rely on a process called “hairy-footed flower visitation,” in which pollen becomes attached to the hairs on their legs and bodies as they feed on nectar. When they visit another flower, some of this pollen is transferred, allowing for pollination to occur.

The life cycle of bee flies begins with females laying eggs often near burrows of host insects, such as bees, wasps, but they can also host on beetle grubs, caterpillars, flies and grasshoppers. The eggs hatch into a worm-like maggot that feeds on the host.

Bee flies are also important indicators of the health of pollinator communities. Because they are sensitive to changes in the environment and require specific habitats and food sources, their presence or absence can signal changes in the overall health of the ecosystem. In addition, their role as predators of other insects can help maintain a healthy balance of species in the garden.

To attract bee flies to a pollinator garden, it is important to provide a variety of flowers that bloom throughout the growing season. Bee flies are active from early spring to late fall, so having a variety of flowers that bloom at different times will provide a continuous food source for them. Some of the flowers that are attractive to bee flies include penstemon, milkweed, goldenrod, and asters.

In addition to providing a variety of flowers, it is important to provide a habitat for bee flies. This can be done by providing areas of bare soil or mulch where they can lay their eggs, as well as areas of vegetation where their larvae can feed. Providing shelter, such as small rocks or logs, can also create a habitat for bee flies.