Flies can be one of the more annoying pests in the house. But there a lot of flies who have beneficial roles in the garden. Some are great pollinators, rivalling bees and beetles, while others are predators of a host of garden pests. The common bottle flies, house flies, stable flies, and smaller fruit flies are generally seen as pests in the house, becoming common in warmer months, and feeding on food wastes and scraps. But the flies of the garden are much more exciting.
In North America there are around 18,000 species of flies and counting. Only around 200 of there are considered pests of humans and animals. These includes the aforementioned bottle and house flies, fruit flies, stable flies, deer flies, horseflies, and others. But even many of the pests do some pollination work. I have observed a number of bottle and house flies on flowers, pollinating. Mostly it is their larvae which is a problem.
Flies in the garden come in a wide range of sizes, colors, and types. There are many which are mimics of other insects, especially wasps, ants, and bees. They do this to keep predators at bay.
Flower Flies in the Garden
There are around 870 flower flies in the garden in North America, with about 100 in the Central Great Plains Region. Also known as hover flies, these are the main flies that mimic bees and wasps, though there are others. They are also commonly called by their Family Name, Syrphid flies. They do about 1/3 of all pollination in the garden. And about 1/3 of all of them have larvae which predates aphids, scales, and other soft-bodied insects which are pests. All flies have 2 wings, and the flower flies have a false vein, called a spurious vein, in each wing, distinguishing them from other flies.
In my gardens I have identified 27 species of flower flies, and some other species which mimic flower flies. Finding flies in the garden, just as with other insects, like moths and beetles, is always exciting for me.
Drone Flies – Eristalis
With about 99 species in North America, it is one of the more common of the flower flies in the garden. The adults are mimics of bees and bumblebees mainly, while the larvae eat small organisms in stagnant or pooled water. They are called drone flies because they often have the appearance of drones (male bees). So far, I have found 6 species in Kansas, 2 of which are introduced from Europe.
- Yellow-shouldered drone fly
- Transverse-banded drone fly
- Common drone fly (introduced)
- Black-shouldered drone fly
- Orange-legged drone fly (bumblebee mimic)
- Eurasian drone fly (introduced)
Calligrapher Flies in the Garden – Toxomerus
These flies are often seen flying around humans during a party or picnic, and are mistakenly called sweat bees. There are around 170 species, all native to North America. The adults are pollinators of a wide range of flowers, including those of perennials, shrubs, and trees. Larvae feed on different kinds of pests or other insects.
- Margined Calligrapher – the larvae feed on aphids, thrips, caterpillars, and mealybugs.
- Maize Calligrapher – the larvae feed on corn pollen and sap, but are not considered a major pest.
- Eastern Calligrapher – larvae feed on aphids and mites.
Aphideaters – Eupeodes
As one of the more important species of flower flies, the aphideaters do just what their name says, eat aphids. I have observed 2 species in the Central Great Plains, but there are 90 species in the Genus. The adults are larger than the previous 2 genera of flower flies, but also mimic bees. They have been seen on a wide variety of flowers. And the larvae feed on aphids on vegetable crops and trees mainly. So, if you have aphids on your cabbage or corn, there are likely to be aphideater larvae too, so do not spray!
Other Flower Flies in the Garden
There are many other flower flies in the garden that you may see if you spend as much time looking for pollinators and insects as I do. I love my flowers, but the insects which visit are even more interesting to me. So I plant a wide variety to ensure that I seed a wide variety of life, from insects and birds, to spiders and reptiles. See you in the garden!
- Shiny bogfly – the larvae feed on decaying vegetation in wetlands and bogs.
- Oblique stripetail – the larvae feed on a wide host range, including aphids, mites, caterpillars, psyllids, mealybugs, and whiteflies.
- Tufted globetail – the larvae feed on mites, aphids, thrips, and caterpillars, mainly on food and vegetable crops.
- Northern plushback – the larvae feed in aquatic environments as filter feeders.
- Broad-banded hornet fly – the larvae feed on rotting wood.
- Wavy mucksucker – the larvae feed in stinking and mucky soil.
Tachinid Flies in the Garden
There are over 1300 species of tachinid or bristle fly in North America, and around 16 introduced species. As it usually happens, bringing in an introduced species to control another species often backfires. On introduced species brought in to control gypsy moth, does attack the caterpillars of the moth, but also the caterpillars of many native moths. All the larvae of tachinid flies feed on other insects as parasitoid, meaning they kill their host. I have found 16 species in the Central Great Plains, thus far.
- Swift feather-legged fly – the larvae are parasites of squash bugs and leaf-footed bugs.
- Hornworm tachinid fly – as the name suggests, the larvae are parasitoids of hornworm caterpillars, including the tomato hornworm.
- Cylindromyia intermedia – the larvae is a parasitoid of stinkbugs.
- Hemyda aurata – the larvae is a parasitoid of the spined soldier bug, which is a predator of other insects.
- Trichopoda lanipes – the larvae is parasitoid of stink bugs.
- Gymnoclytia occidua – the larvae is a parasitoid of cabbage butterfly caterpillars and stinkbugs.
- Cylindromyia interrupta – – the larvae is a parasitoid of moth caterpillars and true bugs.
Bee Flies
If you ever want to try to get a really good photo of something, but want it to dance and hover around so that you cannot get a good shot, try to photograph a bee fly. I struggle more with these flies than anything else I photograph. They just do not stay still very long! With about 900 species in North America, and more than 5000 worldwide, it is one of the largest families of flies. I have only photographed 8 species so far in the Central Great Plains. Bee flies lay their eggs in the nests of their host , and the hatching larvae feeds on either the food left for the host’s larvae, or the host itself.
- Bomber fly – a new species for me in 2023, the larvae use bees as a host.
- Greater bee fly – the larvae use solitary bees and wasps as its host.
- Exoprosopa fasciata – the larvae feed on solitary bees.
- Sparnopolius confusus – the larvae are a parasitoid of June beetles.
- Black bee fly – the larvae is a parasitoid of tiger beetles.
Mydas Flies in the Garden
Mydas flies look like large wasps or hornets. When I first came across my first example of these, feeding on Rattlesnake Master, I was unsure if it was a fly or wasp. They resemble the great black digger wasps that I see so often on swamp milkweed by the lake. There are 17 species of mydas flies in North America. The larvae of mydas flies are predators of beetle grubs, while the adults are generalist pollinators.
Thick-Headed Flies
With 66 species in North America; these are one of the smaller genera of flies. The larvae of these flies are parasitoids of solitary bees and wasps. The adults pollinate, and are mimics of wasps. I have come across 5 species in the Central Great Plains.
Plants to Attract Beneficial Flies in the Garden
If you are wanting more of the beneficial flies, whose hosts include caterpillars, stinkbugs, squash bugs, or aphids, plant some of the following flowers around or within your gardens.
- Tall sedum
- Ornamental Onion
- Chives
- Common Boneset
- Lantana
- Asters
- Rue
- Golden Alexanders
- Wild Carrot
- Yarrow
- Sunflowers
- Rudbeckia
- Goldenrod
- Mint
- Rattlesnake Master
Conclusion
Some flies are friends and some flies are foes. But trying to rid the garden of the foes means killing the friends. Again, diversity in your garden plays a key role in determining whether or not you can keep pests at bay. If you allow more species of insects, whether bees, butterflies, flies, wasps, or bugs, or others, then you are more likely to have more friends than enemies in the garden. So allow for the flies in the garden.
Happy planting!
