Aerodynamically bumblebees aren’t supposed to fly, but they do it anyway. Hoverflies do something even more amazing: they hover! But why do hoverflies hover, and how do they do it? We explore the science behind insect flight in this article.
It is quite rare to come across phenomena that break the laws of science.
The flight of the hoverfly is one such case that defies the conventional laws of aerodynamics that holds true to flights, helicopters, and more.
How? Let us find out.
How Many Types of Hover Flies Are There?
Flower fly populations are abundant worldwide. You will be fascinated to know that there are approximately 6,000 species of hoverflies globally.
They can adapt well to various climatic conditions, which is why you can find them in all regions except Antarctica and deserts.
Also, 62 hoverfly species are found in America. You can spot them in Ohio, Pennsylvania, Kentucky, West Virginia, and many other states in the US.
Adult hover flies prefer to be around flowering gardens as they are the ideal sites to provide primary food sources like nectar and pollens.
They like to lay their eggs in places that are infested with aphids, so if you have both things in your garden, then it is likely that you will find hoverflies.
Do All Species Hover?
Almost all hoverfly species can be spotted actively hovering over a wide range of flowers.
Since they are active flower visitors, they are often considered excellent pollinators.
Also, the hover fly larvae are ferocious predators of aphids, scale insects, and other soft-bodied arthropods.
Due to this, farmers use these bugs for biological control of aphid infestations. A bunch of larvae can comfortably eradicate entire aphid colonies in days.
No wonder why they are called beneficial insects.
Why Do Some of Them Hover?
Hoverflies get their name because of their ability to stay suspended in the air during flight, like a drone. But not all of them hover.
There is a particular species of hoverfly that are called drone flies.
A drone fly is an excellent mimic of a Honeybee. They, too, have bee-like black and yellow stripes on the abdomen.
These drone flies hover around the flowers to be able to feed efficiently.
However, hovering also helps them attract mates.
Research has shown that the stability and duration of the hovering help to attract the female. The more steady they are in mid-air, the more the chances of impressing a mate.
Also, these insects will keep hovering around you if you are drenched in sweat.
This happens because hoverflies are particularly attracted to the salts in human sweat and fall on the skin to lick them.
How Do Hoverflies Fly?
The hovering ability of hoverflies is one of the most interesting facts about them.
These flies constantly keep adjusting the frequency of their wingbeats to the wind pattern to stay afloat during windy days. How amazing is that?
A strong gust of wind cannot blow away a skilled hoverfly.
On rare occasions, you can also spot them around flowers flying backward.
Flexible Wings
The primary reason behind this is the flexible pair of wings. Hoverflies have one of the most flexible wings in the insect kingdom.
The versatile nature of their pairs of wings is off the charts; they can bend and twist these wings at a 45 degrees angle and at a frequency of 300 Hz.
These wings help to maintain the perfect angle to be able to hover.
Leading Edge Vortex
According to the laws of conventional aerodynamics, insects like bumblebees and hoverflies are not supposed to be able to fly.
The leading edge vortex is a process that allows these insects to fly. It is this process that helps these insects to defy the laws of aerodynamics.
As the name suggests, a vortex is created along the leading edge of their wings; This creates a low-pressure zone on top of the wings.
As per Bernoulli’s theorem, the low-pressure zone adds an upward lift that helps them fly.
Air Viscosity
Another reason insects like bumblebees and hoverflies can fly is because of the viscosity in the air.
Viscosity adds resistance when these insects beat their wings.
The dragging action involved sweeps more air which results in higher resistance.
The additional resistance gives a stronger push to support the weight of the insects.
These observations were made by John Maynard Smith and M.J. Davies in the 1950s.
This was done through an experiment where they etherized a few hoverflies and pasted them on a pin.
Later they surrounded them with metaldehyde particles and conducted flash photography to record the length of exposure.
The resulting pictures were quite underwhelming according to modern standards but strong enough to record the above observations.
Frequently Asked Questions
What are hoverflies attracted to?
Hoverflies are attracted to any area that has an abundance of flowering plants.
They hover around these flowers to mate and consume pollens and nectar.
Also, in the initial life stages as larvae, they love to be around aphid populations as they are the primary food source.
You can attract them to your garden by having bright-colored flowers nearby.
Why do Hoverflies hover around you?
Hoverflies are especially attracted to the salts present in human sweat.
If you are drenched in sweat, hoverflies will hover around you to lick and consume the sweat beads.
To avoid this, use sweat repellents that will keep you dry on hot sunny afternoons.
What is the purpose of a hoverfly?
In an earlier stage of the life cycle as larvae, these insects consume aphids, scale insects, and more to attain enough nutrition to transition into the pupal stage.
Once they grow up, they fall and hover around flowers to consume nectar and pollens and to find mates.
Where do hoverflies go at night?
Various species of flies and insects are usually attracted to bright lights at night. Once they spot a light source, they start flying toward it.
Also, some insects search for a safe spot to rest after the sun goes down. You can find them on twigs, branches, and on the undersides of leaves at night.
Wrap Up
Technically insects like bees and hoverflies should not be able to fly.
The experiments conducted by John Maynard Smith and M.J. Davies in the 1950s explained how these insects could fly despite the laws of physics being stacked against them.
We hope the article helped you get some insight into the amazing capability of flight that these insects possess.
Thank you for reading!
Bee/Fly with Yellow Striped Eyes? March 30, 2010 Saw this on the patio a couple days ago. Thought it was a bee at first, but the yellow striped eyes were pronounced. It’s about the size of a common bee or fly. Do you have any idea what this might be or what would cause the markings on the eyes? Kyle B. Long Beach, California
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Hi Paulo – I found the exact same insect today in Chch 21/10/11 and have a link of what this is. A “threelined hoverfly” which are flies that pollinate flowers?!
see -http://www.landcareresearch.co.nz/research/biosystematics/invertebrates/invertid/bug_details.asp?Bu_Id=229
Thanks for the information. We will try creating an actual link for the site you provided
http://www.landcareresearch.co.nz/research/biosystematics/invertebrates/invertid/bug_details.asp?Bu_Id=229
Sericomyia militaris
Hi, we have just found in our house. what a great looking fly. we were worried that it may be a pest,
Hover Flies are beneficial insects.
Sorry, also in Christchurch New Zealand
I don’t see much for an ID, but my wife & I did catch & bring back quite a few similar flies that reminded us of bees from the far side of Lyttelton Harbour, that were sitting on a creek bridge hand-rail in the shade. (Christchurch – NZ) & some still breed at our place. They were easy to catch & we were informed by an entomologist that they were bee flies. Hope this helps.
Bee Flies are a different family. This is a Hover Fly in the family Syrphidae.
Today I found one of these on my flower I got a few photos 24/5/2015
You can send images by using our standard form at the Ask What’s That Bug? link on our site.
8/25/2016 We just found one in our yard in Rancho Cucamonga Cal.
I just took a few pictures of one in south Florida!!
Just saw one in West Florida
Scored a pic of this fly in Riverside, CA. Wow! Like something from Sci-Fi
We also has one come through the house today (chch) and our first thought was what is it? Like a fly yet a wasp detail. Have these always been in new Zealand? Truly amazing looking fly. Thankful for this great website!
Hover Flies are found in New Zealand.
I saw one on my porch in Long Beach,CA.
I photoed one in my garden. In Shillong, Meghalaya, India.
Found one floating in our pool in Covina,CA.
I photoed one in Roma, Italy. At the public park.
According to BugGuide: “A widespread Old World species introduced to California and Florida” so finding one in Rome would support its European range.
I took photo of one in Gauteng, South Africa the other day.
I took a pboto of one in Johannesburg South Africa
5/25/2019,We just saw in our garden.
Where is your garden located?
I took fotos of one sleeping on a leaf of my Bougainvilla in my garden in Potchefstroom, North-west Province, South Africa last night.
just took a photo of the same fly in my garden in Syria Damascus suburb – Annabk
I also clicked a picture near Pacific ocean ensenada Baja California mexico
Saw one in my garden yesterday. Altadena, CA. Thought it was a bee, then noticed it’s crazy eyes. Definitely mesmerizing, for sure.
For work I hydro-jet sewer lines. Most of the times when I’m jetting over a open manhole one Flower Fly enterS the manhole and hover there. This is in the city of Costa Mesa.
Found one of these flies on my flowers just sitting there. Sept. 21, 2021. Stockton, California
Just saw one and took a photo as it sat on my jade plant on my balcony in SPAIN missing a wing. I’ve never seen one before.