The words “flys” and “flies” are homophones, which means they sound the same but have different meanings. This often leads to confusion about when to use each word. In this comprehensive guide, we’ll clear up when to use “flys” versus “flies” once and for all.
An Overview of Flys vs. Flies
First let’s cover the basic definitions of flys and flies
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Flies are the plural form of the noun “fly,” which means an insect, or the plural present tense form of the verb “to fly,” which means to move through the air.
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Flys was historically used as the plural form of “fly” when referring to a type of horse-drawn carriage, or the plural form of “fly” referring to the flaps on pants. However in modern English “flys” is considered incorrect.
So in most cases today, “flies” is the proper usage and “flys” is incorrect. But as we’ll explore, there are some exceptions.
When to Use Flies
As the Plural of the Insect
If you are referring to multiple winged insects, always use “flies”:
- The room was full of flies buzzing around.
- Fruit flies like to gather around ripe produce.
As the Plural Verb Form
When using “fly” as a verb meaning to move through the air, use “flies” for the plural present tense conjugation:
- The bird flies over the meadow.
- My brother flies hang gliders as a hobby.
You would also use “flies” for the past participle and gerund forms:
- The hawk has flown across the countryside.
- Pelicans were flying along the coast.
When to Use Flys
There are a only a couple niche cases where “flys” can be used correctly:
For Historic Carriage Usage
In England in the 1800s, a “fly” was a type of light horse-drawn carriage. The plural form was “flys”:
- The gentlemen arrived in flys at the manor for the ball.
Unless you are writing historical fiction set in 19th century England, this usage of “flys” is obsolete today.
For Multiple Zippers
A “fly” can refer to the zipper flap on pants. Thus, “flys” could theoretically be used when referring to multiple zippers:
- The factory was manufacturing flys for jeans.
However, this usage is extremely rare. “Flies” would still be more common.
For Multiple Theater Spaces
In stage theater, the space above the stage is called the “fly.” Again, the plural “flys” is possible but not common:
- The stagehands were adjusting the flys before the show.
Once more, “flies” would be more widely used and understood.
Remembering Flys vs. Flies
Because flies is correct in nearly every scenario, the easiest rule of thumb is to always default to “flies” instead of “flys.”
To help remember, note that:
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The word “flies” has the same letters as “experience” and “expert,” which reminds us that writers with a lot of experience always choose flies.
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There is no need to add the letter Y to present tense verbs like “he flies” instead of “he flys.” “.
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There are very few occasions to use the obscure definitions of “fly” that take the plural flys.
Examples of Flies vs. Flys in Sentences
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INCORRECT: The horse-drawn flys travelled down the cobblestone street.
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CORRECT: The horse-drawn carriages travelled down the cobblestone street.
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INCORRECT: There were flys all over the rotting fruit.
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CORRECT: There were flies all over the rotting fruit.
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INCORRECT: The dancers flys gracefully through the air.
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CORRECT: The dancer flies gracefully through the air.
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INCORRECT: The factory made blue jean flys.
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CORRECT: The factory made blue jean flies.
FAQs About Flys and Flies
Is it “time flies” or “time flys”?
Time flies is correct. For example: Time flies when you’re having fun!
What’s the difference between flys and flies?
Flies is the plural of the insect fly and the verb fly in the present tense. Flys was used historically for carriages and pants zippers, but flies is standard today.
When should I use flys?
You should avoid flys in nearly all modern contexts. Only use it for historical carriage references or if intentionally using an obsolete plural form.
Is flies the past tense of fly?
No, flew is the past tense and flown is the past participle of fly. Flies is the present tense plural conjugation.
Conclusion
The plural flys was used historically for carriages and pants zippers, but flies has become the standard spelling today. To remember, think that experienced writers always opt for flies over flys.
Following this basic guidance will help you confidently choose either flies or flys depending on the context. Knowing the difference will improve your writing and help you use these homophones properly.

Commonly Misspelled Words Like Flies or Flys
Many words in English have tricky spellings, and “flies” vs. “flys” is no exception. Here are a few examples of commonly misspelled words that often trip people up:
- Who vs. Whom: “Who” is the subject of a sentence, and “whom” is the object of a verb or preposition. Example: “Who is coming to dinner?” vs. “To whom did you give the gift?”.
- Grateful vs. Greatful: The correct form is “grateful,” meaning thankful. “Greatful” is a common misspelling. Example: “I’m grateful for your help. ”.
- Truly vs. Truely: “Truly” is the correct spelling. “Truely” is a misspelling. Example: “She truly believes in the cause. ”.
- Dying vs. Dieing: “dying,” which means “getting close to death,” is the correct form. “Dieing” is a frequent misspelling. “The plant is dying because it isn’t getting enough water.” ”.
By staying aware of these common mistakes, you’ll ensure your writing remains accurate and clear.
Common Mistakes with Flies or Flys
One of the most frequent errors people make is using “flys” when they should be saying “flies. ” Here’s a quick rundown of the common mistakes and how to fix them:
- Using “flys” instead of “flies” when referring to insects. Wrong: There are many flys buzzing around the room. Right: There are many flies buzzing around the room.
- Confusing the verb “flies” with the noun form. Wrong: The bird flys gracefully through the air. Right: The bird flies gracefully through the air.
- When it should be “flies,” you should use “flys” in written or formal situations. ”Wrong: She always flys to New York on business. Right: She always flies to New York on business.