Syrphid flies as pollinators and pest control
By Laura Weingartner
Have you ever seen what you thought was a yellowjacket flying from flower to flower in your garden? Chances are you were looking at a member of the syrphid fly family. This black and yellow striped insect hovers like a hummingbird over flowers in search of energy-rich nectar. In the process of feeding, its hairy body gets covered in pollen, which will transfer to another flower, aiding with the incredibly important role of pollination. They are hairier than yellowjackets, making them more efficient pollinators and giving them the alternative name of flowerflies.
Syrphid flies are important pollinators in Alaska for many wild plants, including some much-loved berries like blueberries, lingonberries and cloudberries. Most aren’t picky when it comes to flowers, making them valuable pollinators for cultivated plants as well. Researchers estimate they visit at least 72% of global food crops that need pollinators. Farmers and scientists worldwide are gaining interest in these flies, not just as pollinators but also as pest control agents.
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| In July, 2023, a syrphid fly (Helophilus neoaffinis) searches for nectar on a grass of Parnassus flower in Mayo, Yukon, Canada. Photo by Kim Selbee. |
Syrphid flies are important pollinators in Alaska for many wild plants, including some much-loved berries like blueberries, lingonberries and cloudberries. Most aren’t picky when it comes to flowers, making them valuable pollinators for cultivated plants as well. Researchers estimate they visit at least 72% of global food crops that need pollinators. Farmers and scientists worldwide are gaining interest in these flies, not just as pollinators but also as pest control agents.
About 40% of species of syrphid fly larvae are aphidophagous, meaning they feed on aphids. Researchers have observed that females often lay their eggs close to aphid outbreaks, sometimes even discriminating against older, larger aphid colonies in favor of smaller but more promising colonies, ensuring food for their offspring. Their ability to hover may help them spot and scrutinize these outbreaks. While the larvae develop, they can consume hundreds of aphids, conveniently helping out the plants, farmers and gardeners.
There are over 6000 identified species of syrphid flies worldwide, nearly 900 of which are found in North America. Not all species’ larvae eat aphids. The larvae show an amazing variety of eating habits. Dead animals, decaying plants, leaves, sap, fungus, dung, ant eggs or other insects are all on the menu for syrphid fly larvae.
Despite the larval food preferences, nearly all adults eat nectar. But the mouth parts differ between species, giving them access to differently shaped flowers. The long flexible snout, called the proboscis, of some syrphid flies allows them to access nectar in deep and narrow flowers. Flies with a shorter proboscis go for shallower and more open flowers. Adult flies, mainly females, will also eat pollen, which is thought to be required for ovary development.
Syrphid flies may be mistaken for yellowjackets or other stinging insects that also eat nectar and pollen. One way to distinguish one from the other, according to Derek Sikes, curator of insects and professor of entomology at UAF, is to count their wings; flies have one pair of wings, while wasps have two. Or, if it stings or bites, it’s not a syrphid fly. Monitoring the insect’s behavior can also help, as syrphid flies can hover seemingly motionless for periods of time, while wasps fly more erratically. Additionally, syrphid flies have small heads, big eyes and short antennae compared to a wasp’s larger head and long, thick, elbowed antennae.
The syrphid fly’s mimicry of stinging bees and wasps may be why they aren’t a well-known pollinator, but sounding and looking like insects that can bite and sting can help them avoid birds and other predators. This phenomenon of resembling unpalatable organisms is called Batesian mimicry and is another reason these flies are so fascinating.
Attracting these insects by providing flowers for the adults could benefit pollination and pest control and give some recognition to these under-appreciated flies.
There are over 6000 identified species of syrphid flies worldwide, nearly 900 of which are found in North America. Not all species’ larvae eat aphids. The larvae show an amazing variety of eating habits. Dead animals, decaying plants, leaves, sap, fungus, dung, ant eggs or other insects are all on the menu for syrphid fly larvae.
Despite the larval food preferences, nearly all adults eat nectar. But the mouth parts differ between species, giving them access to differently shaped flowers. The long flexible snout, called the proboscis, of some syrphid flies allows them to access nectar in deep and narrow flowers. Flies with a shorter proboscis go for shallower and more open flowers. Adult flies, mainly females, will also eat pollen, which is thought to be required for ovary development.
Syrphid flies may be mistaken for yellowjackets or other stinging insects that also eat nectar and pollen. One way to distinguish one from the other, according to Derek Sikes, curator of insects and professor of entomology at UAF, is to count their wings; flies have one pair of wings, while wasps have two. Or, if it stings or bites, it’s not a syrphid fly. Monitoring the insect’s behavior can also help, as syrphid flies can hover seemingly motionless for periods of time, while wasps fly more erratically. Additionally, syrphid flies have small heads, big eyes and short antennae compared to a wasp’s larger head and long, thick, elbowed antennae.
The syrphid fly’s mimicry of stinging bees and wasps may be why they aren’t a well-known pollinator, but sounding and looking like insects that can bite and sting can help them avoid birds and other predators. This phenomenon of resembling unpalatable organisms is called Batesian mimicry and is another reason these flies are so fascinating.
Attracting these insects by providing flowers for the adults could benefit pollination and pest control and give some recognition to these under-appreciated flies.
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