13 Interesting Facts About Deer Flies [Horse Fly Vs Deer Fly]

Flies are everywhere. Isn’t it? There are numerous types and species of flies, including the Deer Flies. Deer flies, also known as sheep flies in some parts of the United States, belong to the family Tabanidae and are generally large flies with big bright eyes and large clear wings with black bands around them.

These flies are larger than the common flies, but at the same time, smaller than the Horse fly and are dispersed all over the world except Iceland, Greenland, and Hawaii.

There are over 250 different species of Deer Flies and are usually considered as bloodsucking pests to humans and cattle.

Somewhat around 100-800 eggs are laid by Deer Flies in batches on or around damp/wet vegetation. Interesting enough, Isn’t it? Well, they may seem annoying and irritating to people sometimes, however, an inquiry of their livelihood, features and habits can definitely bring out something interesting about them.

Here are 13 such informative and knowledgeable facts about Deer Flies relating to their lives, eating habits, lifespan, distinctive characteristics and differences with that of Horseflies.

13 Interesting Facts About Deer Flies

This article intends to present the 13 most important facts about Deer Flies and portrays some of their differential characteristics. The knowledge about their lives and life-span, eating habits, livelihood, and their major differences with Horse flies is the main interest of this article.

1. How Long do Deer Flies Live?

Deer Flies generally have an adult lifespan of 30-60 days. However, their total lifespan including all the stages (i.e Larva, Pupa, and Adult) revolves around 1-3 years.

The lifespan of Deer Flies, like any other flies, depends upon various factors including temperature, food availability, and climate.

It has been observed that Flies that develop under warmer conditions and have access to moderate food, grow faster and tend to survive for longer periods. This has been equally observed for Deer Flies and their different species.

2. Where Do Deer Flies Live?

Deer Flies are usually found in damp, aquatic, wooded, or wetland environments such as ponds, streams, or marshes and are distributed all over the world.

Their activity reaches the peak during the months of June and July throughout the greater portions of their areas of distribution.

The female Deer Flies usually prefer to lay 100-800 batches of eggs around the edges of water bodies in old leaves or rotten logs of wetlands and moist vegetation. The Larvae hatches and falls into these water bodies, and feeds on organic matter present in the environment.

Most of the Deer Fly species require some sort of wet area for their habitat, however, some Paddock adaptive species of Deer Flies are found in drier areas too.

3. What Attracts Deer Flies?

Deer Flies are primarily attracted towards their prey by sight, smell, or by the detection of carbon dioxide that they utilize for breathing.

Deer Flies are also attracted towards body heat or warmer temperature, shiny surfaces, motion or movements, colors of darker shades (especially blue), and lights during the nighttime.

What Color Attracts Deer Flies?

Deer Flies are apparently attracted towards colors and prefer darker colors over lighter ones. Dark Blue or Navy Blue color seems to be probably the most attractive colors for Deer Flies. While Deer Flies get attracted to darker colors, they tend to ignore lighter colors like White.

4. What Eats Deer Flies?

There is a wide range of creatures that feed upon Deer Flies and include them in their dietary preferences, starting from Amphibians like Frogs, Insects like Dragonflies, to Birds such as Swallows. 

The most important natural predators of Deer Flies include Frogs and Toads, Spiders, nest-building Wasps and Hornets, Dragonflies, Robber flies, some distinctive species of Birds such as Swallows, Killdeers, and Flycatchers, and a number of  Hymenopterans of Genera Vespula, Crabo, and Bombyx.

5. What Do Deer Flies Eat?

Deer Flies generally feed on nectar, pollen, honeydew, and probably insect excreta. However, Female Deer Flies also consume and enrich their diet with the blood of other creatures in order to develop eggs.

Deer Flies, in their Larvae stage, usually feed primarily on rotten organic matter that are available to them in or around water and certain small creatures.

They don’t feed during their Pupa stage. And later, after the completion of their Pupa stage, they emerge as adults and start consuming nutritious food supplements such as nectar and pollen.

Female Deer Flies are however required to add blood into their diet since they need blood to produce viable eggs.

6. Where Do Deer Flies Nests?

Different species of Deer Flies are found in different habitats on the basis of their adaptations. While most of the Deer Flies tend to prefer spending their time in or around wet and marshy areas, some rare species of them are also found in drier areas.

Deer Fly Larvae generally develop in or around the edges of water bodies such as ponds, streams, and wetlands. Adult Deer Flies spend their time resting primarily on vegetation.

While most of them are found along hedgerows, edges of the wood, or even in the forests, other species prefer open areas such as old fields. However, the majority of the Deer Flies tend to opt for a wet and moist habitat rather than drier areas.

7. Why Do Deer Flies Hate People?

Deer Flies generally don’t hate people, rather they tend to chase people and suck their blood since their diet includes the blood of humans and other animals!

In addition to nectars and pollen, Female Deer Flies are required to have a good quantity of blood meal in order to produce fertile eggs.

Male Deer Flies are more concerned about pollination, while the Female Deer Flies need the blood of mammals to yield viable eggs, for which they don’t have any other choice than to chase people and obtain their protein requirements from the animal blood.

They use their scissor-like Mandibles and Maxillae to suck up the blood, which is primarily responsible for making their bite a lot more painful.

8. What time of Day are Deer Flies more Active?

Deer Flies are usually more comfortable with higher levels of temperature and are therefore most active during the hottest hours of the day.

Deer Flies are active only during the day and especially in the time period between the three hours after sunrise and the two hours before sunset.

They are mostly active under direct sunlight during specific periods of time in the summers, which is usually the period between May and July.

Deer Flies generally tend to prefer temperatures above 22°C (71.6° F) and are therefore usually found hanging out mostly during the hottest hours of the daytime.

9. What Tree’s Do Deer Flies not Like?

Although Deer Flies can seem irritating and annoying, and at the same time extremely hard to repel, there are some plants and trees that are generally assumed to be capable of repelling these flies away.

Some of these plants and trees that can keep these flies away to some extent include Basil, Bay Laurel, Lavender, Tansy, Rosemary, Pennyroyal, Citronella, and Eucalyptus. Along with plants, essential oils can also help in repelling these flies to some extent.

Some people often claim that the mixtures of certain essential oils such as Peppermint, Lavender, or Citronella can easily be utilized to effectively drive out these bloodsuckers.

10. How Long is Deer Fly Season?

The Deer Fly Season usually lasts for quite a long time starting around late May and lasting up to late July or early September.

Deer Flies are Summer Flies and are predominantly found in the months of May-September. As discussed earlier, Deer Flies usually prefer a temperature above 22°C and therefore tend to stay active for most of the hottest hours of the day.

Because of their attraction towards warmer conditions, they are most active throughout the summers and this makes their season comparatively a longer one lasting for more than three months.

11. Why Do Deer Flies Suddenly Disappear?

Deer Flies generally disappear suddenly during the nighttime and the winters since they prefer higher temperatures for their activities.

The higher temperatures are offered by the Summertime and the daytime for which Deer Flies tend to be most active during the hottest part of the day. Deer Flies usually utilize their sight to detect their prey and hunt them in order to suck blood which is also possible only during the daytime.

Thus, Deer Flies are active directly under the sunlight and prefer to take refuge under leaves, branches, on tree trunks and stems of tall grass and plants at night.

12. How Fast can a Deer Fly Go?

The speed of Deer Flies is approximately 9-10 mph.

There are more than 100 different species of Deer Flies spread all over the world, and therefore their speed varies greatly somewhere between 9-10 miles per hour on average. They are known to be excellent flyers and can take flight faster than mosquitoes and some other flies.

13. Horse Fly Vs Deer Fly

Horse Flies and Deer Flies share more similarities than differences. Both of these flies are generally found in wet and marshy areas dispersed all across the globe, and the females suck blood in order to develop fertile eggs.

They are mostly active during the daytime and can be quite a nuisance for humans as well as animals.

The most important differences between them are observed in their size and appearance. Horse Flies are comparatively larger than Deer Flies with an average length of 1½ to 1¼ inches where Deer Flies are usually about ¼ to ½ inches long.

Horse Flies are therefore larger in size than Deer Flies by 1 inch which means they can easily be distinguished from Deer Flies by simply looking at their size.

In respect to their appearances, Horse Flies tend to differ from Deer Flies significantly. The Antennae of Horse Flies are shorter than their head and have a thick base, while the Antennae of Deer Flies are longer than their head and are uniformly slender.

Horse Flies have clear or uniformly cloudy wings, whereas Deer Flies usually have dark bands on a clear background. However, their similarities are more than their differential characteristics.

Final Words:

Ultimately after a long thorough discussion, we can definitely attribute Deer Flies to be one of the distinctive species of Flies that have their own peculiarities and characteristics.

However, they can be extremely irritating and a nuisance to people because of their bloodsucking habits. They can fly at a greater speed than many other species of flies and are naturally equipped with scissor-like ports to suck blood efficiently.

They are busy throughout the daytime and are hard to repel through insecticides. Their distinctive behaviors and characteristics are worth knowing and acknowledging.