Notice the large eyes that meet at the top of the head and wings that stand out from the body on this bee fly on a ninebark blossom. Flies mimicking bees have huge eyes that meet at the top of the head and one pair of wings that stand out from the resting body compared to two on bees. Their antennae are short and stubby and mouth parts are for sponging or sucking. (Submitted photo/Merabeth Steffen)

As I wander around my gardens during growing season, one of my pleasures is watching the activity of the many pollinators visiting the flowers. I know they are gathering the protein-rich pollen and sugar-rich nectar they need for survival.

However, taking a closer look, I see that it’s not all bees and butterflies. A large group of flies are engaged in the same activity.

That they look like bees and flower-visiting wasps is called mimicry. By resembling, or mimicking, stinging insects, they are less likely to be grabbed by predators lurking in the flowers looking for a meal. They’re not going to sit still to make careful observation possible, but at a glance, structural differences can be seen.

Flies have huge eyes that meet at the top of the head, and that is the ID I use because that is easiest to see. They also have one pair of wings that stand out from the resting body compared to two on bees. Their antennae are short and stubby and mouth parts are for sponging or sucking.

Flies are valuable pollinators. They actively pollinate in areas of high latitude and altitude where bees are rare, and they become active in early spring before most bees. The value of fly pollination to food crops is approximately $300 billion annually, and they are available commercially to pollinate seed crops, which must be grown in enclosed systems to prevent cross pollination.

Flowers with a putrid odor are preferred by some flies. Think rotting meat, garbage, carrion, dung or blood. The flower color that attracts them is pale or dull to dark brown or purple. Others like flowers that are radially symmetrical and open such as daisies. Still others prefer musky, spicy or a yeasty scent such as carnations.

Flies from three families easily can be spotted in your garden. They are flower flies, bee flies and bottle flies.

The flower flies or syrphids are the most recognized. They also are called hoverflies due to a feeding behavior that does not require landing on flowers. They can be black and yellow, black and red or metallic colored. Their bodies are somewhat hairy.

While adult syrphids feed on nectar and pollen, the larvae of some species feed on aphids and other pests making them valuable predators. I often spot hoverflies around blooming lamb’s ear.

Many bee flies are hairy and may resemble bumblebees. Look for a long proboscis or feeding tube. They are out early in spring, and I have observed them feeding on spring beauty. Some are parasitoids.

Their larvae inhabit the larvae or caterpillars of other insects feeding until they pupate and kill the host. Monarchs and early spring bees often fall victim.

Blue and green bottle flies are valuable pollinators and favor plants in the cabbage, onion, carrot, and composite families. They also provide a valuable service as decomposers.

For more information and nice photos of pollinating flies, go to http://go.osu.edu/flypollinators.

Steffen is an Ohio State University Extension master gardener volunteer in Mahoning County.