English spelling can be surprisingly tricky. Some words follow neat patterns while others seem determined to break the rules. Flys or flies is a perfect example.
At first glance, flys might look like the natural plural of fly. After all, many English nouns simply take -s at the end. But English spelling changes when certain words end in a consonant followed by y.
The correct form in standard American English is flies. You use flies when you mean more than one flying insect. You also use flies as the third-person singular present-tense form of the verb fly.
That gives you two common uses:
- Noun: “Several flies were buzzing around the kitchen.”
- Verb: “The eagle flies over the mountains.”
The spelling flys isn’t the standard form for either use in ordinary English. Once you understand why fly changes to flies, the distinction becomes much easier to remember.
Quick Answer
Flies is the correct spelling in standard English. Flys is generally incorrect when you’re referring to the plural of fly or the third-person singular form of the verb fly.
Use flies in sentences such as:
- “There are several flies in the room.”
- “The bird flies across the lake.”
- “She flies to Dallas every month.”
- “Time flies when you’re having fun.”
The basic spelling pattern is:
fly → flies
When fly functions as a noun, flies means more than one fly. When fly functions as a verb, flies agrees with a singular third-person subject such as he, she, it, or a singular noun.
| Word | Correct? | Main Use |
| fly | Yes | Singular noun or base verb |
| flies | Yes | Plural noun or third-person singular verb |
| flys | No in ordinary standard English | Usually a spelling mistake |
So if you’re wondering “flys or flies?”, choose flies in normal English writing.
Comparison Overview
The easiest way to understand flys vs. flies is to look at how each form behaves in a sentence.
| Feature | Fly | Flies | Flys |
| Singular noun | Yes | No | No |
| Plural noun | No | Yes | No |
| Base verb | Yes | No | No |
| Third-person singular verb | No | Yes | No |
| Standard spelling | Yes | Yes | No |
| Example | “A fly landed here.” | “Two flies landed here.” | Incorrect: “Two flys landed here.” |
Consider these four sentences:
- A fly landed on the table.
- Several flies landed on the table.
- I fly to Chicago regularly.
- She flies to Chicago regularly.
Notice how the spelling changes according to both number and verb subject.
That distinction is the key to the entire topic.
Main Differences Between Flys or Flies
The main difference is simple: flies is the standard English form while flys is not used as the ordinary plural or verb form of fly.
However, flies doesn’t have just one grammatical function. It can represent two different forms depending on the sentence.
Flies as a Plural Noun
When flies functions as a noun, it refers to two or more insects or to multiple things called fly.
For example:
“The flies gathered around the fruit.”
Here, flies means more than one insect.
Other examples include:
- “I saw three flies near the window.”
- “The flies kept buzzing around the food.”
- “Several flies landed on the wall.”
- “The restaurant installed screens to keep flies outside.”
The singular form is fly:
“A fly landed on my hand.”
The plural form is:
“Five flies landed on my hand.”
The spelling doesn’t become flys. The final y changes to i, followed by -es.
Flies as a Verb
Flies also works as a verb.
It’s the third-person singular present form of fly.
Compare:
- I fly.
- You fly.
- We fly.
- They fly.
- He flies.
- She flies.
- It flies.
For example:
“The airplane flies over the city every morning.”
The subject airplane is singular. Therefore, the verb becomes flies.
You wouldn’t write:
“The airplane flys over the city.”
The correct version is:
“The airplane flies over the city.”
This same pattern appears with birds, insects, people, aircraft, and figurative expressions.
Why Is It “Flies” Instead of “Flys”?
The answer comes from a common English spelling rule involving words ending in consonant + y.
When a word ends in a consonant followed by y, the y usually changes to i before adding -es.
For example:
- fly → flies
- cry → cries
- try → tries
- carry → carries
- study → studies
- reply → replies
- hurry → hurries
The pattern looks like this:
consonant + y → consonant + ies
So:
fly → flies
The word fly ends in l + y. The l is a consonant. Therefore, the standard spelling changes the y to i and adds -es.
Why Doesn’t Every Word Ending in Y Follow This Pattern?
That’s where another useful distinction appears.
If a word ends in a vowel + y, English usually keeps the y and simply adds -s.
Compare:
| Singular | Plural |
| fly | flies |
| cry | cries |
| city | cities |
| baby | babies |
| boy | boys |
| day | days |
| key | keys |
| toy | toys |
Notice the difference:
consonant + y
- city → cities
- baby → babies
- fly → flies
vowel + y
- boy → boys
- day → days
- key → keys
- toy → toys
This is why flys looks plausible but doesn’t follow the standard spelling pattern.
“Flies” as the Plural of “Fly”
One of the most common questions about flys or flies concerns the plural of the insect.
The singular noun is fly.
The plural noun is flies.
Singular Examples
- “A fly landed on the plate.”
- “There’s a fly near the window.”
- “I noticed a fly buzzing around the kitchen.”
Plural Examples
- “Several flies were near the garbage.”
- “The flies disappeared after the door closed.”
- “We saw dozens of flies outside.”
- “The fruit attracted many flies.”
A useful test is to place a number before the word.
If you can say one fly, you need the singular.
If you can say two flies, you need the plural.
You wouldn’t write:
“two flys”
Instead, write:
“two flies”
Fruit Flies
The expression fruit flies provides an especially familiar example.
- “Fruit flies can appear around ripe fruit.”
- “The kitchen had a problem with fruit flies.”
- “Keep produce covered to reduce fruit flies.”
Here, flies is clearly plural because it refers to multiple insects.
“Flies” as the Third-Person Singular Verb
The second major use of flies is grammatical rather than nominal.
Flies is the third-person singular present form of the verb fly.
The basic pattern is:
| Subject | Verb |
| I | fly |
| You | fly |
| He | flies |
| She | flies |
| It | flies |
| We | fly |
| They | fly |
This pattern is similar to other English verbs.
For example:
- I study → She studies
- They try → He tries
- We carry → She carries
- I fly → He flies
The word flies therefore doesn’t always mean insects.
Consider:
“The bird flies south every winter.”
There are no insects in that sentence. Flies is a verb describing what the bird does.
Examples of “Flies” as a Verb
- “The eagle flies above the valley.”
- “She flies to Los Angeles every summer.”
- “The plane flies at a high altitude.”
- “That airline flies to several international destinations.”
- “Time flies when you’re having fun.”
- “The kite flies well in strong winds.”
Context tells you whether flies is a noun or a verb.
Fly vs. Flies: A Clear Grammar Guide
The difference between fly and flies becomes much easier when you identify the word’s grammatical role.
| Word | Function | Example |
| fly | Singular noun | “A fly is on the wall.” |
| fly | Base verb | “They fly every Friday.” |
| flies | Plural noun | “The flies are everywhere.” |
| flies | Third-person singular verb | “The bird flies quickly.” |
Here’s a simple rule:
Use “fly” for one insect.
“There is one fly in the room.”
Use “flies” for multiple insects.
“There are five flies in the room.”
Use “fly” after I, you, we, and they.
“They fly every week.”
Use “flies” after he, she, it, or a singular noun.
“She flies every week.”
This four-part pattern solves most fly vs. flies questions.
Read More: Traveled or Travelled: UK vs US Spelling Explained With Examples
Why People Write “Flys” by Mistake
The spelling flys isn’t random. It comes from a reasonable guess about how English plurals work.
Many English nouns form plurals simply by adding -s:
- book → books
- car → cars
- table → tables
- phone → phones
- house → houses
Someone who knows this pattern might naturally assume:
fly + s = flys
But English has several spelling patterns that modify the basic rule.
Words ending in consonant + y commonly change y to i before -es.
So:
fly + es → flies
This is a classic case where English spelling requires you to look at the ending of the base word, not just add a letter mechanically.
Is “Flys” Ever Correct?
In ordinary standard English, flys isn’t the correct spelling for either the plural noun or the third-person singular verb.
However, unusual spellings can appear in proper names, usernames, brands, titles, or other deliberately chosen names.
For example, a company could theoretically choose Flys as part of its official name. In that case, the spelling belongs to the name rather than ordinary English grammar.
That’s an important distinction.
If you’re writing a normal sentence about insects, write:
“The flies are buzzing.”
If you’re describing what a bird does, write:
“The bird flies over the trees.”
Don’t use flys simply because it appears somewhere as a name or stylized label.
Common “Flys” vs. “Flies” Mistakes
A few incorrect patterns appear repeatedly.
“The flys are everywhere.”
Incorrect: “The flys are everywhere.”
Correct: “The flies are everywhere.”
Here, the word refers to multiple insects. Therefore, flies is the correct plural.
“She flys to New York.”
Incorrect: “She flys to New York.”
Correct: “She flies to New York.”
The subject she is third-person singular. The verb therefore takes the -ies form.
“Time flys when you’re having fun.”
Incorrect: “Time flys when you’re having fun.”
Correct: “Time flies when you’re having fun.”
Here, flies is a verb. The subject is time, which is singular.
“The airplane flys every morning.”
Incorrect: “The airplane flys every morning.”
Correct: “The airplane flies every morning.”
The singular noun airplane requires the third-person singular verb flies.
“I flies to work.”
Incorrect: “I flies to work.”
Correct: “I fly to work.”
This mistake goes in the opposite direction. I takes the base verb fly, not flies.
Flies in Common Expressions and Phrases
The word flies appears in several familiar English expressions.
“Time Flies”
The phrase time flies means that time seems to pass quickly.
“Time flies when you’re having fun.”
Here, flies is the verb.
The subject is time, which is singular. Therefore, the correct form is flies.
“When Pigs Fly”
This expression describes something extremely unlikely or practically impossible.
“He’ll clean his room when pigs fly.”
The phrase uses fly, not flies, because the implied subject is plural pigs.
That’s a useful reminder that verb agreement matters.
“Like Flies”
The expression like flies can describe something occurring in large numbers or falling rapidly.
“People gathered around the concert entrance like flies.”
Here, flies is a plural noun.
“Fly in the Ointment”
A fly in the ointment means a small problem that spoils an otherwise good situation.
“The unexpected delay was the fly in the ointment.”
This expression uses the singular noun fly.
These examples show why you can’t simply choose fly or flies based on appearance. You need to consider the sentence.
FAQs:
Is “flys” a correct word?
Flys isn’t the standard spelling for the plural of fly or the third-person singular present form of the verb fly. In ordinary English writing, use flies.
Is “flies” the plural of “fly”?
Yes. Flies is the standard plural of the noun fly.
For example:
“One fly is on the wall.”
“Several flies are on the wall.”
Is “flies” a verb?
Yes. Flies is the third-person singular present form of the verb fly.
For example:
“The bird flies over the lake.”
Is it “time flies” or “time flys”?
The correct phrase is “time flies.”
Here, time is a singular subject, so the verb takes the third-person singular form flies.
Why does “fly” become “flies”?
Because fly ends in a consonant followed by y. In this spelling pattern, the y changes to i before -es.
Therefore:
fly → flies
Conclusion:
When it comes to flys or flies, the correct choice in standard English is flies. The word fly becomes flies when you’re talking about more than one insect. It also becomes flies when you use it as the third-person singular present-tense verb. So, if you’re writing an email, school assignment, article, or everyday message, stick with flies. It’s the correct spelling and the one your readers will expect.
