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Flies, Pacific Northwest

Greenback Fly, Flies
Greenback Fly, Photo By Bud Logan

All insects play an important part of our ecosystems, even Flies As part of food chains, insects provide sustenance for countless other animals. For instance, just one crow can eat as many as 16 bushels of insects in one year. So all insects are beneficial and necessary. It’s just that with some insects, it’s harder to remember that they are a necessary part of the world around us.

The Pacific Northwest has many, many flies and although we do not like them, at least the biting ones. They do serve a purpose.

Other flying insects have long been considered flies, like dragonflies, mayflies, fireflies, butterflies. But these all belong to other orders of insects. True flies are insects of the Order Diptera, which are often referred to as the true flies. They are always listed as 2 words separated like house fly or crane fly while others are listed as 1 word like dragonfly or damselfly.

Robber Fly
Robber Fly, Photo By Bud Logan

The compound eyes are usually large, often occupying most of the head. Mouthparts are modified and combined into a sucking proboscis, which is highly variable in structure.  Some mydas flies have mouthparts that don’t function. No true flies bite in the true sense, but puncture the skin of their victims and suck blood.

The order Diptera is usually divided into two suborders, the Nematocera, a suborder of elongated flies with thin, segmented antennae and mostly aquatic larvae, consisting of the mosquitoes, crane flies, gnats and the brachycera, a suborder of short-horned flies represents a major division of the Diptera containing approximately 120 families and a great diversity of species, morphological innovations, and life history strategies. The name brachycera or shortened horn refers to their shortened antennae, a reduced antenna with fewer than 8 antennal.

Green Bottle Fly, Flies
Green Bottle Fly, Photo By Bud Logan

About 150,000 species of living Diptera have been described in approximately 10,000 genera and 150 families. The true number of species is probably many times more than this. Many species of them are cool or cold adapted and the relative abundance of Diptera in the total insect fauna is higher in northern countries such as Canada than in the world as a whole. In high arctic sites, the number of species is greater than that of all other insects combined.

The astounding success is owed to their great versatility in the exploitation of habitats and their ability to utilize every possible sort of food. They are ubiquitous and are abundant in individuals as well as in species number. They are an important food source for other animals.

Many are parasitic on other insects and help keep their populations under control. Some herbivorous species have been successfully used to control weeds. Many are important pollinators of plants. Many are invaluable as scavengers and are vital in aiding the decomposition of plant and animal material.

They are the insects most known to infect humans and domesticated animals with deadly diseases. Bloodsucking flies transmit many diseases, including malaria, yellow fever, and sleeping sickness.

Anthomyiid Fly
Anthomyiid Fly, Photo By Bud Logan

The larvae of Anthomyiid Fly are, for the most part, plant eaters, but some feed on dead and decaying organic material and a few are parasites of grasshoppers.

The adults feed on nectar and play an important role as plant pollinators. They occasionally feed at flowers with exposed nectaries, such as members of the carrot family. The larvae have various habits, sometimes feeding on dung, scavenging in bird nests, and other rotting materials. The larvae of some species feed on bulbs and can become pests of onions and lilies.

The Anthomyiid flies are small to medium-sized and are usually yellow, brown, gray or blackish. They have a well-developed calypter at the base of each wing, the wings are sometimes clouded with a gray or brown color and the legs are yellowish to black.

Black Fly adult females are blood feeders and are often serious pests, just go fishing when they are out and you will know what l mean.

Livestock has died from being bitten by a large number of black flies. They also transmit diseases to wildlife in North America, and to humans in other parts of the world.

The larvae are aquatic and occur in fast-moving streams. The larvae attach themselves to rocks and other objects by means of a sucker at the posterior end of the body and filter food from the water as it flows past.

Adults occur in late spring and early summer, often near the stream from which they emerged.

Black Flies are small grayish or blackish flies with short legs, broad rounded wings, and a humpbacked shape.

Crane Fly
Crane flies, Photo By Bud Logan
The Crane flies are mostly found in damp situations where there is abundant vegetation, although some are found in dry grassland habitats and even deserts, there are many crane flies in the Pacific Northwest, sometimes, in the fall, we could have up to 50 at one time in our house. The more common ones on the coast are the European, Pichia Contans, and the Marsh Crane flies.

The larvae are called leatherjackets due to their tough skin. Some larvae are aquatic or live in wet conditions. The larvae of other species live in the soil or in fungi, mosses, and decaying wood. The larvae feed mostly on the decomposing organic matter with a few of the aquatic species being predaceous. The adults live only a few days and most of them do not feed.

Species of the genus Chionea are small and wingless and are found on snow in winter.

Crane flies are medium to very large sized flies. They are usually gray or brown but can be many colors like bright copper, the body is elongated and slender, and they have long narrow wings and long and slender legs. They could be confused with large mosquitoes but crane flies do not have a long proboscis and do not bite. The wings are often clouded or patterned and they have a ‘V’ shaped groove on the top of the thorax.

Deer-Horse Fly
Horse Fly, Photo By Bud Logan
The female Deer-Horse Fly are bloodsucking and the bites can be very painful. They can be serious pests of livestock and humans. The males are found on flowers and feed only on nectar and pollen. The adults are often seen around swamps, marshes, and ponds.

The larvae are aquatic and are mostly found in shallow water or moist soil. Most of the larvae are predaceous.

Some deer-horse fly transmits diseases such as tularemia and anthrax in the United States and Africa. These flies are medium to large sized with stout bodies. The eyes are often brightly colored with a pattern of stripes. The eyes touch each other on the top of the head in males and are separated in the females.

Deer fly
Deer Fly, Photo By Bud Logan
Deer flies are up to 12 mm long, a bit larger than house flies but still smaller than horse flies. They are black and yellow, black or sometimes grey. Their wings are crossbanded with black stripes, and their eyes are brightly colored (gold, green, orange, or blue). The genus name Chrysops, in fact, is derived from the Greek words chrysos, which literally means gold eyes.

Female flies require blood in order to make viable eggs. Reproduction is not possible without this. Typically, females wait in shady areas for a possible prey to pass by, a deer, cattle, other large undulates and of course humans. They always seem to go for that spot you can’t reach and when one bites you, you know it.

Horsefly females are also very aggressive blood feeders. although the males do not bite but instead feed on pollen and plant nectars. Female horse flies usually bite large, stationary animals, attacking the legs or body.  Horse flies have a range of animals that they bite, this includes livestock, humans, pets, and birds.

Robber Fly
Robber Fly, Photo By Bud Logan
Adult robber flies are predators of other flying insects. They attack a variety of insects, even those that are larger than themselves.

They insert their short but strong proboscis into the insects to suck their body fluids. Some of the larger species can give a painful bite if handled.

Adults are common in dry, open and sunny places. The larvae are found in soil, decaying wood or fallen leaves where they are predaceous on the eggs, larvae, and pupae of other insects.

Robber flies are small to very large sized, hairy with usually a long slender abdomen. The legs are long and spiny, the lower part of the face or sometimes the entire face is covered with dense bristles, and the top of the head is excavated. Most are dark colored but some are black and yellow and look like bees.

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