If you’ve spent any amount of time outside around the world, the chances are that at one point or another, you’ve encountered a yellow fly. There’s just no avoiding them! They’re usually buzzing around in plain sight, and they love to land on sweaty skin to drink blood. So what is this yellow fly? Well, stick around because we have everything you need to know about yellow flies right here.
What are Yellow Flies?
“Yellow flies” is the common name for a group of biting, non-stinging insects found in tropical and subtropical climates worldwide. Yellow fly larvae live in wet soil or slow-moving bodies of water, whereas the adult stage prefers moist environments around buildings.
Adult yellow flies measure about 1/8 inch (3mm) long and have black bodies with white spots on their wings. Depending upon the species, they may be either yellow or tan in color. The adults do not bite humans – only the larval stage does that. They are known to transmit diseases such as river blindness to humans via mosquito bites; this disease causes lesions on human skin, which can develop into flesh-eating ulcers if untreated.
Yellow fly larvae like to feed on organic matter such as mud and feces, but they will also eat dead insects and small fish. The female yellow fly deposits eggs in wet soil or water using her long, tube-like mouthparts called an ovipositor.
When the larvae hatch about a week later, they crawl out of the water or soil onto surfaces that may be close to standing bodies of water. They spend about one month maturing into adults before laying their eggs.
Yellow flies are aggressive biters – you’ll know when you’ve been bitten because it itches intensely for several hours after being bitten. The males are attracted to human sweat secretions, whereas the females are more attracted to animal dander or urine.
Yellow Fly Life Cycle
The life cycle of this particular yellow fly has four stages. They are egg, larva, pupa, and adult. The entire life cycle can last up to 14 months during the warmest summer months.
Eggs are laid in clutches of 10-200 eggs on aquatic vegetation close to where they were hatched. They lay their eggs above water so that the eggs will fall into the water for hatching once the larvae have developed enough to swim when it rains.
Their eggs are yellowish-brown in color and have a diameter of 0.82mm. Eggs take anywhere from 13-23 days to hatch depending on temperature; more specifically, warmer weather speeds up this process considerably while cooler temperatures greatly slow down the development of all stages. Females usually deposit their eggs between the months of July and September.
The larvae of this species develop very quickly, sometimes taking only 2-3 weeks to go through all their stages. The process is greatly sped up by warm weather and can take much longer in cooler conditions.
Once the larvae have hatched, they congregate on vegetation overhanging ponds and lakes where they wait for passing insects such as mosquitoes, mayflies, stoneflies, and larger Diptera (flies), which are their prey.
They grab onto their prey with a sickle-shaped appendage on the third segment called a prehensile labella. This labella contains several rows of teeth that grip their prey while delivering paralyzing saliva before sucking out the liquefied insides.
Yellow Fly Effect on Humans and Animals
Adult yellow flies are extremely active in the months of June, July and August. During these months, they are most often seen in fields near ponds where their prey is abundant. They are also found frequently around wetland areas or with livestock.
Whether it’s a yellow fly biting you or your dog, they all have the same objectives in mind, to feed on blood. These yellow flies are known for their painful bites, lasting up to 15 minutes due to an anti-coagulant found within their saliva that ensures an adequately nourished meal. A strong bite from an adult yellow fly can inflict enough pain to make even the largest mammal run off away from them in haste.
The way they suck blood creates many problems, but it is also important to know that these insects are annoying and can be carriers of different types of disease agents. If an animal gets bitten by yellow flies, the insect transfers bacteria from one host to another, causing disease or even death in some cases.
Among other diseases, these flies can also carry the bluetongue virus, which is very serious for the livestock industry due to its high mortality rate. However, the main question about yellow flies concerns their role as carriers of tick-borne protozoan blood parasites such as Babesia bigemina. It has been found that yellow flies are a competent vector of bovine babesiosis, which causes significant economic losses to the livestock industry due to the high mortality rate in calves in their first year of life.
Yellow flies feed on most mammals such as rabbits, hares, and sheep. They can fly up to 850 meters during one flight period (August-October). They inject saliva into the blood vessel during feeding, causing hypersensitivity reaction, inflammation, and fever.
The bitten animals start licking or biting the bitten area, leading to hair loss and the formation of bare patches. The inflammatory reaction caused by bites does not cause any serious harm, but it still reduces an animal’s weight gain.
Anemia is a common condition for heavily bitten animals which subsequently leads to retarded growth and milk production. Yellow flies also transmit the bluetongue virus from one host to another, causing high fever, swelling of the tongue or around the mouth, and death in some cases.
Can yellow flies carry disease?
Yellow fly larvae pose more of a threat than adults because they feed on feces or decaying matter. This can put them in close proximity to water sources that are often contaminated with dangerous bacteria, so if you come into contact with the yellow fly larvae, you could pick up some bacterial infection.
The only species of “yellow fly” that is considered medically relevant is called Diachlorus ferrugatus, also known as the black salt-fly or brackish-water yellow fly. This type of insect typically lives near sea coasts but will move inland when humidity levels rise.
It carries several different types of hemorrhagic fever viruses, which can cause fever, rash, and severe internal bleeding. Yellow flies are tiny, though, so a human would have to be bitten more than a thousand times to contract one of these deadly viruses.
How can you protect yourself against yellow fly bites?
There is no completely effective way to repel them, but some measures will help keep the number of bites down.
Wearing light-colored clothing isn’t much good because they are attracted to dark colors as well as exhaled carbon dioxide. The best thing to do is apply insect repellent containing DEET to your skin or permethrin to your clothing before going outside for an extended time during mosquito season – this should deter yellow flies.
When out on the water, a head net is also a good investment. When you’re inside, use a fan to keep air circulating and prevent the yellow flies from landing on exposed skin. Some people have reported that using nail polish or petroleum jelly to coat exposed skin works well – others say that it keeps them away for only about 20 minutes.
How to get rid of Yellow Flies?
How to Get Rid of Yellow Flies Outside?
It is essential to remember that yellow flies are attracted to water and heat. This means that they thrive where there is plenty of standing water and sunshine.
If you do not have a yard and live in an apartment, try drying the bottom floor and setting fans outside blowing towards your windows or doorways. Keeping these areas dry can help prevent them from finding their way inside to find blood meals.
Other ways on how to get rid of yellow flies outside include:
- Spraying plants with rubbing alcohol
- Cleaning trash bins
- Using fine-mesh under doors and windows to stop them from coming inside
- Sealing cracks in the house where they could be entering
How to Get Rid of Yellow Flies Inside?
It is important to eliminate their places to lay eggs. This can be done by keeping an eye out for standing water and removing it.
Areas where water may collect include:
- Trash bins
- Washing machine hose connection
- Broken pipes
- Old tires
With outside methods including keeping doors shut at all times while enjoying time indoors, keeping out of direct sunlight if possible (or wearing long sleeves and pants), and using fine mesh screens wherever possible, there are ways to prevent them from entering and getting close to you.
If these pests do manage to get inside, there are ways of making the home unattractive for them, such as:
- Hanging sticky fly traps everywhere
- Spraying permethrin outside and keeping it dry
- Stuffing weather stripping around doors and windows
- Keeping outdoor lights off at night
By preventing them from entering, killing those that do find their way into areas with screens and spraying, and making the home unappealing by drying it out with fans and fly traps, these annoying nuisances can be kept at bay with a few simple steps.