House Flies may not bite, but they are more than an annoyance because they delight in unhygienic places. Muscid flies and their maggots mostly breed in manure. They live for around 30 days during warm weather, but can live as long as five months. 90% of all flies in dwellings are House Flies. Unfortunately it is a perfect host for carrying many types of bacteria: gangrene, Typhoid, leprosy, tuberculosis, dysentery, bubonic plague, listeria, even food poisoning and many more. It is scary that a House Fly potentially carries twice as many pathogens as a cockroach, yet we tend to think of a cockroach infestation as being of a greater concern.
I tend to check to make sure it isn’t a deer fly that is about to bite me, but then I just put all other flies in a fly category. However, taking a closer look at them I found that there are quite a number of variations. Many fly species in the related families Muscidae, Calliphoridae, Sarcophagidae and Tachinidae closely resemble one another and all four can be found in houses.
The House Fly; Musca domestica can be identified by the 4 black stripes on the thorax. This fly doesn’t bite, unlike face flies, stable flies and horn flies, which are also in the Muscidae family. It is hard to find something nice to say about flies other than it doesn’t bite, but it does have some cool abilities. They can fly as far as 13 miles from their birthplace and can fly at five miles per hour and up to 6 thousand feet high. Their wings beat 200 times every second! Their eyes are quite amazing too. Each eye has four thousand separate lenses in each eye, which gives them wide-angle vision and makes it so hard to swat at them. I guess their ability to cling to window glass and hang upside down is quite a talent. They have hairy footpads that secrete a kind of “glue” made of sugars and oils and two claws that they use to get unstuck when they want to move. How about this for a not so fun fact: the descendants of one pair of flies, if they all lived and reproduced normally would cover the earth to a depth of 8 feet in a year!
Flesh Flies; Sarcophaga get their name because many lay their eggs in open wounds. They feed on decaying meat, although the majority of the species feed on small carrion, like dead insects and smaller vertebrates. They also eat decaying vegetable matter and excrement, so may be found around compost piles and pit latrines too. They are very similar to House Flies, but they only have 3 black lines on their thorax.
Tachinid Flies can be difficult to distinguish from House Flies and Flesh Flies. They come in many shapes and sizes, but many have gray stripes. They tend to be hairy when compared to Flesh Flies and House Flies, but a microscope is needed to accurately identify them.
Blow Flies are also commonly associated with decaying animal flesh. Many of them have distinctive metallic blue or green coloration, so they are mostly easier to distinguish from House Flies.
So basically House Flies are bad news in my view, but flies are of considerable ecological importance. True Flies are important pollinators, second only to Hymenoptera insects, of which bees belong. True flies are of the order Diptera, which is derived from the Greek meaning two wings. These insects use only a single pair of wings to fly. Their hind wings have been reduced to a club-like balancing organ known as halters.
As long as flies stay out of the cottage and don’t bite me, then I am happy to try to enjoy them. So with that in mind, one fly that I have encountered and I don’t have any issues with is the Chaetopsis or Picture Winged Fly.
Chaetopsis or Picture Winged flies are often seen perching face-down on waterside vegetation. They feed on nectar or fluids from decaying plant material, which seems a little more civilized! They are quite comical, especially when the males wave their decorative wings to perform courtships to the females. Each of its wings can move independently, as if delivering a miniature semaphore message for another picture wing fly to decipher. There are many different types of Picture Winged flies, but they all tend to be small and have wings that are spotted or banded with black, brown or yellow.
Another type of fly that is quite interesting is the Crane Fly or Tipulidae. Tipulidae is one of the largest groups of flies and they resemble an oversized mosquito with elongated legs and wings that are often held out at a 45-degree angle to their body. They are commonly called Daddy Longlegs.
There are over 1,500 species of crane flies in North America, so I am not going to attempt to identify this one, but the long legs and they way it holds itself indicates a Crane Fly. Mosquitoes have proboscis and they hold their body in a “humpback” position when resting. Crane Fly legs are about twice the size of their bodies. They only live for a couple of days in their adult form and their only purpose is to mate and lay eggs. This means most don’t eat, so they don’t bite or sting. Like moths, they are attracted to light, so they are prone to joining us indoors and the way they dance around people can be disturbing, but it is really quite harmless.
I was quite surprised to find that Midges are also classified as true flies. There are about 500 species of Chironomids in Canada. Chironomids are nonbiting midges. There are Midges that bite, but they are in the Ceratopogonidae fly family. Sandflies fall in this group.
Midges are often mistaken for mosquitoes. One way you can tell them apart from mosquitoes is when they rest. Their two front legs hover above the surface, where as mosquitoes lift their hind legs. The males have feathery antennae, which you do not see on mosquitoes, so this one is a male.
They have very short lives and only live a few days, but can be a nuisance during those few days. They have very poor flying ability and are often blown about on wind currents. Their eggs are laid in shallow water. The larvae are good for the ecosystem as a cleaner of decaying organic matter in the water. They are also a good food source for other aquatic insects and some fish. Like Crane Flies, adult Midges do not feed and spend the few days of their life mating.
It seems flies are quite diverse and I really shouldn’t tar them all with the same brush. I still can’t say I am fond of them, but it has been interesting to study a little about them and see just how varied they are. I certainly will take a closer look in future and see them through a slightly different lens.