## Saturday, August 24, 2019

### How Fast Can A Fly Fly?

First, before revealing the answer, let’s consider size relative to speed. If you are six feet tall, 10 miles an hour doesn’t seem very fast, but if you were six inches tall it would seen a lot faster. A dragonfly’s top speed is 18 miles per hour and if it were the size of a human that 18 mph would feel like 324 mph. A mosquito’s top speed of 1.2 mph would feel like 40 mph. More on this later.
Considerable research has been on on insect speeds. In 1991 two scientists at the University of California, Berkeley, used a pressure-sensitive plate and high-speed cameras to track eight American cockroaches. They can fly but rarely do and are the fastest when they run on their two hind legs. They hit speed of 3.4 mph.
In 1996 scientists in the Netherlands tested two species of Australian tiger beetles which cannot fly. They are the fastest running insect and they hit speeds between 4.2 and 5.6 mph. That’s 8 feet per second and at that speed its visual system can’t keep up, so it has to slow down to see anything.
The reason they go blind at such high speeds is because they don't gather enough photons (illumination into their eyes) to form an image of their prey. That’s why they have to stop, look around and take off running again. In the middle of a hot pursuit they have to stop three or four times to reorient themselves relative to their prey. The stops don’t hurt it though because it’s so fast that even with them it can can out run whatever it’s chasing.
Measuring body lengths per second is another way of measuring speed. In a contest of speed relative to size, the fastest known species of tiger beetle, Cicindela hudsoni, can run at a speed of 5.6 mph, or about 125 body lengths per second. Usain Bolt, the 100 meter world record holder, runs at 27.3 mph, but 6 feet 5 inches tall that only translates to 6 body lengths per second which is pretty slow compared to a cheetah’s 16 body lengths per second.

A mite found in southern California, known as the Paratarsotomus macropalpis, was recorded at 0.5 mph. With a body length of a little over one quarter of an inch, it equates to 322 body lengths per second.
Throwing out the idea of considering relative speeds though on the logic that size is not normally considered in other speed contests such as fastest land vehicle, according to the Smithsonian, the title of fastest flying insect belongs to the dragonfly, which hits speeds of 35 miles per hour. The fastest butterfly is the West Indian butterfly which can hit speeds of 29.8 mph. Don’t tell Usain Bolt he can’t out run a butterfly.

What about flies? A ale horsefly (Hybomitra hinei) can hit 90.5 mph. Remember the relative speed discussed earlier? That equates to a whopping feels like speed of 4054.4 mph.
A common house fly may travel as far as thirteen miles from its birthplace. It’s wings beat 20,000 times a minute and it zips along at 4.5 mph with a feels like speed of 810.9 mph.