Idaho’s mix of farmland, forest, and high desert creates ideal conditions for one of the most overlooked groups of insects around: flies. Idaho is home to more than 500 different types of flies, ranging from kitchen nuisances to skilled pollinators that quietly support the state’s crops and wildflowers.
Some species bite, some spread bacteria, and others do more good than harm by pollinating plants or breaking down organic waste. Knowing which fly is buzzing around a picnic table, a barn, or a garden bed makes it much easier to decide whether it’s a problem worth solving or simply part of the local ecosystem.
This guide covers 12 types of flies in Idaho, including how to identify each one, where it tends to show up, and what role it plays in the environment.
| Fly Type | Family | Bites Humans? | Typical Setting |
|---|---|---|---|
| House fly | Muscidae | No | Homes, barns, garbage |
| Fruit fly | Drosophilidae | No | Kitchens, orchards |
| Blow fly | Calliphoridae | No | Carcasses, garbage |
| Stable fly | Muscidae | Yes | Barns, pastures |
| Horse fly | Tabanidae | Yes | Fields, near livestock |
| Deer fly | Tabanidae | Yes | Woodlands, trails |
| American Hover Fly | Syrphidae | No | Gardens, flowerbeds |
| Dance fly | Empididae | No | Meadows, wetlands |
| Soldier fly | Stratiomyidae | No | Compost, flowers |
| Spear-winged fly | Lonchopteridae | No | Damp vegetation |
| Hump-backed fly | Phoridae | No | Decaying matter, indoors |
| Tachinid fly | Tachinidae | No | Gardens, fields |
1. House Fly
The house fly (Musca domestica) is the species most people picture when they think of a fly, and it is found in virtually every corner of Idaho. House flies are typically gray in color, have four black stripes on their thorax, measure about 1/8 to 1/4 inch long, and have hairy bodies with compound red eyes made of thousands of individual lenses.
House flies do not bite, but they are still a genuine health concern. They are attracted to decaying organic matter and can lay hundreds of eggs in such areas, which means kitchens, dumpsters, and livestock operations all offer prime breeding grounds. Because they move between filth and food surfaces so readily, they can carry bacteria on their bodies wherever they land. Idaho’s combination of agricultural land and warm summers keeps house fly numbers high from late spring through early fall. Anyone dealing with recurring house fly problems around pets should also check the types of flies that bother dogs, since several biting species overlap with backyard infestations.
2. Fruit Fly
Fruit flies are among the smallest and most familiar pests in an Idaho kitchen. The common species, Drosophila melanogaster, has a translucent yellowish-brown body and bright red eyes, and it rarely grows beyond a few millimeters long. Fruit flies, sometimes called vinegar flies, are drawn to decaying, rotting, and overripe fruit and vegetables, and have a translucent yellowish-brown or tan body with red eyes.
Their reproductive speed is what makes them such a persistent problem. These insects live an average of only 20 days, but during that short window they can lay as many as 500 eggs at a time. A single overripe banana left on an Idaho counter for a few days is often enough to trigger a small outbreak.
Pro Tip: Clean up spills right away, wash produce as soon as it comes home, and store ripening fruit in the refrigerator to keep fruit flies from settling in.
Fruit flies are among the common types of flies in Idaho, and they are commonly found near decaying fruits and vegetables where they feed on yeast and bacteria. Anglers who tie their own patterns may also recognize the name from a different context; the different types of flies used for fishing borrow insect names like this one purely for pattern design, not biology.
3. Blow Fly
Blow flies belong to the family Calliphoridae and are easy to spot thanks to their metallic sheen. Blow flies are larger than common house flies, and several species are characterized by shiny metallic colors, including black Phormia, blue Calliphora, and green or copper Phaenicia.
These flies play an important, if unpleasant, ecological role. Blow flies use their strong sense of smell to arrive quickly at the location of a deceased animal, where they lay their eggs on the decomposing tissue. Their larvae then break the tissue down rapidly, which speeds up decomposition in fields, along roadsides, and around livestock operations. Blow flies make a loud droning buzz and will lay eggs on exposed meat, with green or copper species completing larval development in less than a week while black or blue species take 10 to 15 days. Because they cycle through generations so fast, populations can build up quickly near ranches and rural properties.
4. Stable Fly
The stable fly (Stomoxys calcitrans) looks like a house fly at first glance, but a closer look reveals a key difference. The stable fly resembles the house fly but has a slender, pointed beak with which it pierces skin and sucks blood.
Unlike the house fly, stable flies actively bite, and Idaho’s livestock operations give them plenty of opportunity. It is normally an outdoor fly that feeds on domesticated animals, but it may enter houses in rainy weather, and while it can deliver a painful bite to humans, it is more significant as a pest and disease vector in livestock and pets.
Managing stable flies comes down to sanitation. Controlling stable fly maggots involves weekly disposal of stable manure, urine-soaked straw, moist spilled feed, and decaying vegetation such as lawn clippings or seaweed washed up along shorelines. Horse and dairy operations across Idaho often deal with this species most heavily during late summer.
5. Horse Fly
Horse flies, family Tabanidae and genus Tabanus, are among the largest and most aggressive biting flies found in Idaho. Horse and deer flies are stout and usually medium to large, with most species drab in brown, gray, or black, though many have bright, iridescent, or rainbow-colored eyes; females drink the blood of vertebrates while males feed on nectar.
Their bite is more than just an annoyance. Horse flies range from 3/8 inch to just over an inch long and vary in coloration by species, with some entirely black and others showing colored patterns on their abdomens and wings. Horse flies use sword-like piercing and sucking mouthparts to bite, and can travel up to a mile from their breeding sites while inflicting painful bites that sometimes cause visible, bleeding wounds.
Anyone who spends time near Idaho lakes, rivers, or pastures in midsummer has likely met this fly firsthand. Fly anglers imitate their bulky profile with terrestrial patterns, a connection covered in more detail in the guide to fly-fishing patterns and the insects they mimic.
6. Deer Fly
Deer flies (genus Chrysops) are close relatives of horse flies but noticeably smaller and often more persistent. Deer flies are large flies with brightly colored compound eyes and large clear wings marked with dark bands, and they are larger than the common housefly but smaller than the horse fly.
Deer flies range from 1/4 to 1/2 inch long, are black to brown with yellowish markings, and have clear wings with black or brown patterns that make the wings appear banded. They tend to circle a target’s head persistently before landing, a behavior that makes them feel more aggravating than their bite actually is.
Idaho’s forested trails and wetland edges are prime deer fly territory in summer. Because their bite can cause a sharp, immediate sting, hikers often mistake deer flies for horse flies until they notice the smaller size and banded wings.
7. American Hover Fly
The American Hover Fly belongs to the family Syrphidae, a group known for mimicking bees and wasps despite being completely harmless. The American Hover Fly is found throughout Idaho, and the adult is small, typically reaching only 2 to 3 millimeters in length, with wings usually striped in orange and black markings.
Despite the warning-colored wings, this fly is a garden asset rather than a pest. The larvae feed on plant material and other small insects, while the adults consume nectar and pollen, and their presence provides natural pest control since they feed on many of the same pests that damage crops and gardens.
Gardeners who enjoy attracting beneficial insects may also want to compare notes with the types of bees found in Idaho, since hover flies and native bees often visit the same flowering plants side by side.
8. Dance Fly
Dance flies, family Empididae, get their name from the aerial courtship displays some species perform above meadows and streams. Empididae, commonly known as dance flies, are predatory as adults, hunting smaller insects mid-flight rather than scavenging or feeding on plants.
These flies are also more ecologically valuable than most people realize. Species of dance flies, soldier flies, spear-winged flies, and hump-backed flies are known to visit flowers, making them minor but consistent pollinators alongside their role as predators of other small insects. Idaho’s damp meadows, streambanks, and wetland margins offer the moist conditions dance fly larvae need to develop before reaching adulthood.
9. Soldier Fly
Soldier flies, family Stratiomyidae, are often mistaken for wasps because of their slender bodies and patterned wings. Soldier flies are among the fly families known to visit flowers in Idaho, feeding on nectar as adults while their larvae take on a very different job.
Soldier fly larvae are efficient decomposers, breaking down decaying plant matter, manure, and other organic waste. This trait has made one relative, the black soldier fly, popular in composting and sustainable animal feed programs worldwide, though wild Idaho species mainly stick to natural decomposition roles in soil and leaf litter.
Key Insight: Soldier fly larvae are so effective at breaking down organic waste that several species are now farmed commercially for composting and livestock feed production.
10. Spear-Winged Fly
The spear-winged fly, family Lonchopteridae, is one of the least noticed flies in Idaho simply because of its small size and unremarkable coloring. Spear-winged flies are among the fly groups documented visiting flowers alongside dance flies, soldier flies, and hump-backed flies, which suggests they play a quiet but real role in local pollination networks.
True to the family name, these flies have narrow, pointed wings that taper to a spear-like shape, a trait that separates them from rounder-winged relatives. Larvae typically develop in damp soil, leaf litter, or rotting vegetation, where moisture and decaying organic matter provide both shelter and food. Because spear-winged flies rarely enter homes or bite, most Idaho residents never notice them despite their presence in gardens, wetlands, and shaded yards throughout the growing season.
11. Hump-Backed Fly
Hump-backed flies, family Phoridae, are named for the distinctly arched profile of their thorax. Phorid flies are easily recognized by their humped backs, measure about 1/4 inch long, and are most often found in hospitals and restaurants, though wild populations also thrive outdoors around decaying organic material.
Their movement pattern is almost as distinctive as their shape. Rather than flying in smooth lines, hump-backed flies tend to run erratically across surfaces before taking short, quick flights, a habit that has earned some species the nickname “scuttle flies” elsewhere in the country. Hump-backed flies are also documented visiting flowers in Idaho, adding a small pollination benefit to a family that is more commonly associated with decomposing matter and indoor nuisance issues.
12. Tachinid Fly
Tachinid flies, family Tachinidae, close out this list as one of the most beneficial fly groups a gardener could hope to attract. One notable Idaho species is the bee-like tachinid fly (Hystricia abrupta), which is one of the many types of flies found in Idaho and is considered a beneficial insect that helps pollinate plants.
Beyond pollination, tachinid flies provide a service most homeowners never see happening. Tachinidae are parasitoids of other insects, meaning their larvae develop inside caterpillars, beetles, and other garden pests, eventually killing the host. This makes tachinid flies a natural form of pest control that reduces the need for chemical intervention in gardens and farm fields alike. Because they resemble bees or house flies depending on the species, tachinid flies are frequently overlooked or misidentified. Recognizing their bristly abdomens and stout bodies helps separate them from the pests they are actually working to control.
Idaho’s fly population is far more varied than the handful of pests that show up at a picnic or barbecue. From the disease-carrying house fly to the pollinating tachinid fly, each of these 12 types of flies in Idaho fills a distinct role in the state’s fields, forests, and backyards. Readers curious about how the state’s fly diversity compares elsewhere can check similar breakdowns for types of flies in North Dakota or types of flies in Delaware, and gardeners interested in the state’s full spectrum of flying insects may also want to browse the complete list of Idaho fly species for even deeper identification detail.