Flies, Pacific Northwest
There are more than 100,000 different species of flies including the greenback fly. They are found everywhere in the world, even in Antarctica. They belong to the order of insects called Diptera which means two wings. Most insects have 4 wings.
On the bodies of flies, however, over time, this second set of wings developed into small knobs that are located behind their main wings. These knobs help keep flies steady and balanced when they fly and make them very agile. They can maneuver themselves into intricate flight patterns, they can hover and spin, and even fly backward.
Flies have 6 legs and segmented bodies consisting of a head, a thorax, and an abdomen and sticky feet that enable them to walk upside down. Their special feet enable them to land on smooth surfaces and not fall off.
Flies lay their eggs in the soil, on plants, on the bodies of other animals, and frequently on dead or rotting flesh. Fly larvae are usually called maggots. Different flies dine on different foods.
Flies around the world eat a variety of foods, including nectar, plant sap, blood, other insects, and decaying matter.
Did you know that a mosquito is actually a fly? Of the species of flies that eat blood, only the females are the blood eaters. They need the nutrients in the blood to be able to lay eggs. The males of these species usually dine on nectar from plants and flowers. The species of flies that we call houseflies like to eat human food.
Flies cannot chew. They have to suck up their food. Flies have mouthparts that absorb food like a sponge. Their food has to be in a liquid form in order for them to eat it. They have a tongue shaped like a drinking straw to slurp up their meals. Flies that eat nectar or blood do so by using their tongue which is called a proboscis. Even flies that eat other insects do so by sucking out the insides of their victims. When a housefly lands on our food, it vomits on the food. The digestive juices, enzymes, and saliva in the vomit begin to break down and dissolve the food. The fly can then suck up the liquid food with its sponge-like mouthparts and its proboscis.
If flies eat food from garbage cans or any other source of germy food, some of those germs stick to the fly’s mouthparts and when the fly vomits on its next snack, it transfers some of those germs.
Flies do have their beneficial side. They help control other insect pests. They act as scavengers and recyclers when they feed on decaying waste such as dung and dead animals, just go down to one of the Islands rivers when the Salmon are running and see how the flies quickly breakdown the dead fish on the shore. Of course, they serve as food themselves for other insects and many birds. Flies are also great pollinators. Only bees and some wasps pollinate more plants and flowers than flies.
The Greenback Fly is a favorite snack for many of our house spiders. So if you don’t like flies in your house, encourage spiders to move in.