En boca cerrada no entran moscas is the proverb Spanish parents and grandparents reach for when a child is talking too much, gossiping, or about to say something better left unsaid. Literally: "Flies don't get into a closed mouth." Figuratively: keep your mouth shut and you won't get into trouble. It is one of the most reliably-used proverbs in the Spanish-speaking world, and it packages four pieces of grammar — fronted locatives, post-verbal subjects, sentence negation, and frozen idiomatic articles — into nine syllables.
The text
En boca cerrada no entran moscas.
A clean, complete sentence with a verb, but with the word order rearranged in a way English usually doesn't tolerate. The fronted prepositional phrase opens the sentence; the verb sits in the middle; the subject — moscas — closes it. That sequence is the proverb's main lesson for English speakers.
Word by word
- En: the preposition "in / into." Selected by the verb entrar; Spanish entrar takes en, never ❌entrar a in this fixed proverb (though entrar a
- place exists in some regional usage). For the entrar en / entrar a distinction, see verbs followed by en.
- boca: feminine noun, "mouth." Notice — and this is the first surprise — that there is no article. In everyday Spanish you would say en la boca. The article-less form is a feature of frozen proverbs; we'll come back to it below.
- cerrada: feminine singular past participle of cerrar ("to close"), here used adjectivally. The past participle agrees with the noun it modifies in gender and number: cerrada (fem. sing.) matches boca. The adjective sits after the noun, which is its natural position when the adjective is descriptive and restrictive — it picks out a specific kind of mouth (a closed one), not a general comment about mouths.
- no: sentence negation, placed immediately before the conjugated verb. This is the Spanish negation rule: no
- verb, no exceptions for simple negation.
- entran: third-person plural present indicative of entrar, "to enter." The verb agrees with the subject moscas — plural verb, plural subject.
- moscas: feminine plural noun, "flies." The subject of the sentence, but placed after the verb. Again no article, again a frozen-proverb feature.
En boca cerrada no entran moscas.
A closed mouth catches no flies.
Mejor calladita; ya sabes, en boca cerrada no entran moscas.
Better keep quiet — you know, loose lips sink ships.
The fronted locative
The proverb begins with en boca cerrada — a prepositional phrase of place ("in a closed mouth"). In a neutral SVO sentence the order would be: Las moscas no entran en una boca cerrada — "Flies don't enter a closed mouth." But Spanish freely moves locatives, temporals, and topical phrases to the front of the sentence to set the scene.
This is the same fronting move you see in al mal tiempo, buena cara (a fronted PP topic) and in countless news headlines. The fronted phrase tells the listener: "Here is the situation; now I'll tell you what happens in it." Linguists call this topicalisation.
En esta casa no se grita.
In this house, no shouting.
En invierno, en Madrid, hace mucho frío.
In winter, in Madrid, it's very cold.
Por las mañanas se me cierran los ojos.
In the mornings my eyes just won't stay open.
Post-verbal subject placement
The most interesting thing about this proverb, grammatically, is that moscas — the subject — comes after the verb. English requires the subject before the verb except in marked cases (questions, "here come the…", inversions in literature). Spanish is far more flexible. When the locative is fronted, the subject naturally trails after the verb. The new information — moscas — lands at the end of the sentence, where Spanish prefers to put new information.
The pattern PP — verb — subject is everywhere:
En la nevera quedan dos cervezas.
There are two beers left in the fridge.
En este barrio viven muchos extranjeros.
A lot of foreigners live in this neighbourhood.
En aquel pueblo nació mi abuela.
My grandmother was born in that village.
If you tried to keep English word order in Spanish, you would produce something like ❌Moscas no entran en boca cerrada — grammatical, but stiff, and not the proverb. The proverb form prefers the natural Spanish rhythm: scene-setter, verb, subject.
See the subject-position page for a full treatment of when Spanish puts the subject after the verb.
Negation: no before the verb
Spanish negates a sentence by placing no directly before the conjugated verb. Nothing can come between no and the verb except an object clitic (no me digas, no se lo cuentes).
No entran las moscas si la ventana está cerrada.
Flies don't get in if the window is closed.
No me lo digas dos veces.
Don't tell me twice.
No te preocupes por eso.
Don't worry about that.
This rule applies even when other negative words (nunca, nadie, nada) are in the sentence. If the negative word follows the verb, no is still required: No viene nadie ("Nobody's coming"). The double negative is grammatical and obligatory in Spanish.
The missing articles: frozen idiom mode
In everyday speech you'd say:
- Las moscas no entran en la boca si la tienes cerrada.
Both moscas and boca take articles. The proverb strips both articles out. Why?
Spanish proverbs and set expressions often delete articles to give the phrase a gnomic, timeless quality. The article-less noun feels generic, universal, almost categorial: not a specific mouth, not specific flies, but mouths in general and flies in general. English does the same in some proverbs: "Time heals all wounds" (no article on time).
You can spot this article-less style in many other Spanish sayings:
Perro ladrador, poco mordedor.
A barking dog rarely bites.
Hombre prevenido vale por dos.
A forewarned man is worth two.
Casa con dos puertas mala es de guardar.
A house with two doors is hard to guard.
If you tried to use the proverb's bare-noun structure in everyday speech outside the proverb, it would sound strange:
❌ Anoche entraron moscas en boca.
Wrong — outside the proverb, the articles are obligatory.
✅ Anoche me entraron moscas en la boca cuando dormía.
Last night flies got into my mouth while I was sleeping.
Cerrada as a post-nominal adjective
Cerrada is a past participle (from cerrar) used as an adjective. Spanish past participles agree with the noun they modify in gender and number — exactly like any other adjective. Boca cerrada, libros cerrados, puertas cerradas.
The adjective sits after the noun. In Spanish, descriptive adjectives that restrict the noun's reference (which mouth? a closed one) follow the noun. Adjectives that describe an inherent quality sometimes precede it (la blanca nieve = "the white snow," where whiteness is taken as inherent). For a closer look, see the section on adjective position elsewhere in this guide.
No me gusta dormir con la ventana cerrada.
I don't like sleeping with the window closed.
Las tiendas estarán cerradas el lunes por la festividad.
The shops will be closed on Monday for the holiday.
Who says it, and why it stings a little
The register is didactic and informal. Typical speakers and contexts:
- A yaya (grandmother) to a grandchild who has just said something inappropriate at the dinner table.
- A friend warning another friend not to spread a piece of gossip.
- A teacher gently telling a student who keeps interrupting.
Because the proverb has a faintly admonishing tone, it can sting a little when someone uses it on you. The implicit message — you have just said something you shouldn't have, or are about to — is rarely heard as a pure observation. It is almost always a soft rebuke or a piece of advice meant to land.
A peninsular variant you'll occasionally hear:
En boca cerrada no entran moscas, ni se sale el corazón.
— "Flies don't get in, and the heart doesn't slip out." This extension layers a second idea: silence also protects what's inside. It is less common but worth recognising.
A family of peninsular proverbs about silence and speech
Spanish has a small library of sayings about the wisdom of holding one's tongue. Once you know en boca cerrada no entran moscas, the others slot in.
A buen callar llaman Sancho
"They call the one who knows when to stay quiet Sancho." A nod to Sancho Panza, or possibly older — the proverb predates Cervantes — and a paean to the value of strategic silence. Note the inversion: llaman Sancho with the object Sancho after the verb.
No le contestes; ya sabes, a buen callar llaman Sancho.
Don't reply to him; you know, silence is golden.
El silencio es oro, la palabra es plata
"Silence is gold, the spoken word is silver." A two-part proverb that ranks the two; less folkloric than en boca cerrada but used in elevated registers.
A veces es mejor no decir nada: el silencio es oro.
Sometimes it's better to say nothing: silence is golden.
Quien mucho habla, mucho yerra
"Whoever talks a lot makes a lot of mistakes." Note the headless relative quien — "whoever, the one who." The verb in the second clause is yerra (from errar, "to err"), with the regular -e- → -ie- stem change. This proverb belongs to a high register; older speakers use it with full force.
Cállate ya: quien mucho habla, mucho yerra.
Be quiet now: the more you talk, the more mistakes you make.
Las paredes oyen
"Walls have ears." Used to remind someone that they might be overheard. Common in Spain in political and family contexts alike.
Baja la voz, que las paredes oyen.
Lower your voice — the walls have ears.
Common transfer errors
❌ Moscas no entran en boca cerrada.
Wrong word order — the proverb fronts the locative and trails the subject after the verb.
✅ En boca cerrada no entran moscas.
A closed mouth catches no flies.
❌ En la boca cerrada no entran las moscas.
Not the proverb — adding articles loses the gnomic frozen-idiom quality. Grammatical, but not the saying.
✅ En boca cerrada no entran moscas.
A closed mouth catches no flies.
❌ En boca cerrado no entran moscas.
Wrong — cerrada must agree in gender with the feminine boca.
✅ En boca cerrada no entran moscas.
A closed mouth catches no flies.
❌ En boca cerrada no entra moscas.
Wrong — the verb agrees with the plural subject moscas, even though it precedes it.
✅ En boca cerrada no entran moscas.
A closed mouth catches no flies.
❌ En boca cerrada moscas no entran.
Wrong — negation must immediately precede the verb.
✅ En boca cerrada no entran moscas.
A closed mouth catches no flies.
Key takeaways
- The proverb opens with a fronted prepositional phrase (en boca cerrada), pushes the verb to the middle, and parks the subject (moscas) at the end. This PP — verb — subject shape is one of Spanish's most natural information rhythms.
- Negation no sits immediately before the conjugated verb. Nothing comes between them except clitic pronouns.
- Cerrada is a past participle used as a feminine singular adjective, agreeing with boca.
- The missing articles are deliberate — they mark the proverb's timeless, gnomic register. In ordinary speech, you'd put the articles back.
- Pair this proverb with quien mucho habla mucho yerra, a buen callar llaman Sancho, and las paredes oyen to round out the peninsular discourse on discretion.
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- Tema y focoB2 — Spanish marks topic by fronting a constituent with a resumptive clitic (A Marta no la veo desde hace meses) and focus by reordering or clefting. How the two systems work, how they interact, and how they differ from English.
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- Expresiones fijas con subjuntivoB2 — Lexicalized subjunctive expressions — pase lo que pase, sea quien sea, que yo sepa, cueste lo que cueste — frozen formulas that don't conjugate creatively.