Step outside on a warm Iowa evening and you’ll notice something quickly: flies are everywhere. Some buzz around porch lights, others hover over garden vegetables, and a few will happily leave a bite on bare skin. Iowa’s mix of farmland, wetlands, forests, and cities supports a surprising range of fly species, and knowing the types of flies in Iowa can help you tell a harmless pollinator from a pest that actually deserves attention.
This breakdown covers 15 flies you’re likely to encounter across the state, from familiar kitchen pests to biting insects that show up near ponds and pastures. Iowa’s Diptera fauna is genuinely diverse, spanning families like Anthomyiidae, Asilidae, Bibionidae, Bombyliidae, and Calliphoridae, among many others. Understanding what you’re looking at makes it much easier to decide whether a fly is a minor annoyance or a genuine problem.
1. House Flies
The house fly (Musca domestica) is the fly most people picture when they hear the word “pest.” Every house fly has a dull gray body with vertical lines on top, as well as gold and silver stripes on their face. They belong to the family Muscidae, and house flies are one of the most common fly species found in homes and other buildings.
These flies rarely travel for fun. House flies find their way in while on a quest for food, and their definition of “food” includes garbage, animal feces, deceased animals, compost, and waste water. That diet also makes them effective at spreading bacteria onto countertops and food prep surfaces.
Iowa homeowners aren’t alone in dealing with this species. Neighboring states report nearly identical patterns, and readers comparing regional pest pressure may want to check out the types of flies in North Dakota for a look at how a colder climate shifts the mix. Dogs and other pets can also end up dealing with house flies directly, which is covered in more detail in this guide to types of flies on dogs.
Pro Tip: Tight-fitting lids on trash cans and repaired window screens stop most house fly problems before they start, since these flies enter homes primarily while searching for food sources.
2. Fruit Flies
Fruit flies are tiny, quick-breeding insects best known for swarming around overripe produce. The common species, Drosophila melanogaster, is one of the most studied insects in the world thanks to its short life cycle. These flies have a short lifespan and measure around 3mm in length, with red eyes and bodies commonly found near decaying fruits and vegetables where they feed on the yeast and bacteria that thrive there.
Their turnaround time is fast. With a lifecycle of 10 to 14 days, these flies can quickly become a nuisance, especially in kitchens, dustbins, or anywhere decaying fruit is present. Removing rotten produce and wiping down sticky counters usually solves an infestation within a week or two.
Pest control companies in the Midwest report fruit flies as one of the top three filth flies encountered by homeowners, alongside house flies and phorid flies. Curious how this compares elsewhere? The types of flies in Delaware shows a similar pattern despite the very different climate.
3. Blow Flies
Blow flies belong to the family Calliphoridae and are often mistaken for oversized house flies. Blow flies tend to be black, green, blue, or bronze in color with sponge-like mouthparts, and they are specifically interested in deceased creatures and excrement. Species like Phormia regina are common across Iowa’s fields and yards.
Their attraction to carrion has an unusual practical use. They lay their eggs in dead animals, and forensic entomologists use the development timeline of these flies to determine time of death. That same biology means blow flies can carry bacteria from decomposing material into kitchens and food prep areas.
Preventing blow fly problems comes down to sanitation:
- Store household trash in cans with tight-fitting lids
- Pick up pet waste from the yard promptly
- Remove fallen, rotting fruit from trees
- Seal outdoor compost bins if they attract flies
4. Horse Flies
Horse flies (family Tabanidae, genus Tabanus) are among the largest and most painful biters found in Iowa. These flies are long and gray or black, often with horizontal colored stripes in their eyes, and prefer hot conditions with little wind. Some regional variants, known as “greenheads,” stand out with metallic green eyes.
Only females bite. Both sexes feed on plant protein and nectar, but females also feed on blood to make their eggs. Livestock and pasture areas tend to see the heaviest horse fly activity during the warmest weeks of summer.
Anglers may recognize the name from a different context entirely. Artificial versions of biting insects are a staple of Midwest fly boxes, and the connection between real insects and lure patterns is explored in this guide to different types of flies for fishing.
5. Deer Flies
Deer flies (genus Chrysops) are close relatives of horse flies but noticeably smaller, with patterned wings and iridescent green or gold eyes. They’re persistent daytime biters that tend to circle a target’s head before landing. Unlike most nuisance flies, deer flies carry a genuine health risk.
In the United States, one deer fly species, Chrysops discalis, can transmit tularemia, a bacterial illness sometimes called rabbit fever. Deer flies are one of the few types of flies that transmit disease to people in the United States, which makes them worth taking seriously near wooded trails and wetland edges.
| Biting Fly | Typical Size | Where Found | Bite Severity |
|---|---|---|---|
| Horse Fly | 3/4 – 1.25 inches | Pastures, sunny open areas | Sharp, immediate pain |
| Deer Fly | 1/4 – 1/2 inch | Wooded trails, wetland edges | Sharp pain, can spread disease |
| Biting Midge | Under 1/32 inch | Ponds, marshes, coastlines | Itchy, disproportionate to size |
| Mosquito | 1/8 – 3/8 inch | Standing water, shaded yards | Itchy, disease risk |
6. Cluster Flies
Cluster flies (Pollenia rudis) look similar to house flies but move more sluggishly and have golden hairs on their thorax. Overwintering flies, such as cluster flies, seek warmth and shelter in homes during the colder months, which is why Iowa residents often find them clustered near sunny windows in fall and winter.
Cluster flies don’t breed indoors and don’t pose the same sanitation risk as house or blow flies. Their larvae actually parasitize earthworms outdoors, making them an unusual case among common nuisance flies. Sealing exterior gaps before autumn is the most effective way to keep large numbers from moving in.
7. Drain Flies
Drain flies, also called moth flies, belong to the family Psychodidae. These flies get their name from their fuzzy appearance, which resembles that of a moth, and adults are often found near wet areas such as drains, sewage systems, or damp basements.
Unlike drinking-water pests, drain flies breed in the organic sludge that builds up inside pipes rather than in clean water itself. A quick way to identify them at a glance: tiny fuzzy, moth-like flies near sinks and tubs point to drain (moth) flies rather than any biting species. Running a pipe brush through slow drains usually clears the breeding material they rely on.
8. Mosquitoes
Mosquitoes (family Culicidae) are arguably the most disliked insects in Iowa, and for good reason. Females require a blood meal to develop eggs, and their bites can transmit pathogens in addition to causing itching. Biting flies transmit debilitating diseases to millions of people worldwide, and mosquitoes are the group most associated with that risk in the Midwest.
Reducing mosquito numbers around a property comes down to eliminating standing water:
- Empty and scrub bird baths weekly
- Clear gutters so water doesn’t pool
- Turn over unused buckets, tires, and containers
- Stock ornamental ponds with mosquito-eating fish where practical
Bats provide a natural check on mosquito populations across Iowa’s rural and urban areas alike. Readers interested in these nighttime predators can learn more in this overview of types of bats in Iowa.
9. Green Bottle Flies
Green bottle flies (Lucilia sericata) are close cousins of blow flies, sharing the same family, Calliphoridae. Blow and bottle flies are typically metallic blue or green in color and have a shiny appearance, making them one of the easier flies to spot on sight thanks to their almost jewel-like sheen.
Their larvae feed exclusively on decaying tissue, which occasionally leads to a condition called myiasis in animals with open wounds. Pet owners dealing with fly strike on dogs may find useful background in this guide to types of flies on dogs. In gardens and compost piles, though, green bottle flies mostly just accelerate decomposition.
10. Root-Maggot Flies
Root-maggot flies belong to the family Anthomyiidae, a group well represented in Iowa’s insect records. Anthomyiidae, listed among Iowa’s Diptera families, are commonly known as root-maggot flies. The larvae of species like the cabbage maggot fly tunnel into the roots of cruciferous vegetables, causing wilting and stunted growth.
Home gardeners growing cabbage, radishes, or turnips often notice the damage before they ever see the adult fly, since the larvae work underground. Floating row covers over young seedlings are one of the simplest ways to keep egg-laying females away from vulnerable plants. Gardeners battling other larval pests may also want to compare notes with this rundown of types of caterpillars in Iowa.
11. Robber Flies
Robber flies (family Asilidae) are the predators of the fly world, ambushing other flying insects mid-air with a sharp proboscis. Some species, particularly in the genus Laphria, have evolved to look strikingly like bumblebees, right down to a fuzzy, banded abdomen and thick “beard” around the face.
Despite the intimidating appearance, robber flies pose zero threat to people. They only harm the insects they hunt, and their mimicry is purely a defense against predators that avoid stinging bees. Gardeners who enjoy spotting look-alike insects might also appreciate this guide to types of wasps in Iowa, since robber flies are frequently confused with the real thing.
Pro Tip: Check the wings before assuming an insect is a bee or wasp. True flies, including robber flies, have a single pair of functional wings, while bees and wasps have two pairs.
12. Bee Flies
Bee flies (family Bombyliidae) are furry, hovering insects that visit the same flowers as actual bees, feeding on nectar with a long, needle-like proboscis. A common Iowa species, Bombylius major, is often mistaken for a small bumblebee thanks to its round, hairy body.
Adult bee flies are harmless pollinators, but their larvae have a darker side, developing as parasites inside the nests of solitary bees and other ground-nesting insects. Anyone tracking Iowa’s broader pollinator community may enjoy comparing bee flies with true pollinating species covered in this guide to types of butterflies in Iowa.
13. March Flies
March flies (family Bibionidae) emerge in large, slow-moving swarms early in spring, often around the time their name suggests. Species in the genus Bibio have dark, hairy bodies and weak flight, making them easy targets for birds, frogs, and other insect-eating wildlife.
These flies rarely bite or damage property, and large emergences typically die down within a few weeks. Their sudden appearance and disappearance is a normal part of Iowa’s early-season insect cycle rather than a sign of a problem. Amphibians benefit the most from these seasonal swarms, a connection explored further in this look at types of frogs in Iowa.
14. Biting Midges
Biting midges (family Ceratopogonidae, genus Culicoides) are barely visible but can ruin an evening outdoors. Since they rarely grow larger than 1/32 of an inch long, biting midges, also called no-see-ums, easily get into houses through window and door screens, making them one of the most frustrating biting insects to keep out.
Their habitat preferences explain where the worst bites happen. They are mostly found in wet environments like the edges of ponds, marshes, and lagoons, and biting midges transmit a variety of diseases and, in the U.S., infect livestock with bluetongue virus. Only females bite, since female midges need the protein from blood to begin producing eggs.
Important Note: Biting midges are sometimes confused with other, larger midges in the family Chironomidae that resemble mosquitoes but do not bite at all. Size and behavior, not just appearance, are the best way to tell them apart.
15. Wood Gnats
Wood gnats (family Anisopodidae) round out this list as one of the least troublesome flies on it. Anisopodidae are listed among Iowa’s recorded Diptera families as wood gnats, typically found around decaying wood, damp leaf litter, and rotting plant material.
Adults resemble small, delicate mosquitoes but lack biting mouthparts, so they pose no threat to people or pets. Their larvae play a quiet but useful role in breaking down decaying organic material in forested and shaded parts of the state. Homeowners with active compost piles or wooded lots are the most likely to spot them resting on nearby vegetation.
Living With Iowa’s Flies
Most of the flies on this list are more nuisance than danger, and a surprising number, like bee flies, robber flies, and march flies, actually help control other insect populations or pollinate flowers. The exceptions worth real caution are deer flies, mosquitoes, and biting midges, since all three can transmit disease through their bites.
Good sanitation habits handle the vast majority of indoor fly problems: sealed trash, repaired screens, and prompt cleanup of rotting produce or pet waste. For outdoor biting species, avoiding peak activity hours near water and wearing long sleeves during warm months remains the most reliable defense. Iowa’s insect diversity extends well beyond flies, and readers curious about the state’s broader wildlife may enjoy exploring the types of spiders in Iowa or checking which species appear on the list of endangered animals in Iowa.