La Cucaracha
La Cucaracha ("The Cockroach") is a popular Mexican folk song about a cockroach who cannot walk. The song's origins are unclear, but it dates back at least to the 1910s during the Mexican Revolution. The song belongs to the Mexican corrido genre. The song's melody is widely known and there are many alternative stanzas.

Structure
The song consists of verse-and-refrain (strophe-antistrophe) pairs, with each half of each pair consisting of four lines featuring an ABCB rhyme scheme.

Refrain
The song's earliest lyrics, from which its name is derived, concern a cockroach that has lost one of its six legs and struggles to walk with the remaining five. The cockroach's uneven, five-legged gait is imitated by the song's original, 5/4 meter, formed by removing one upbeat (corresponding to the missing sixth leg) from the second half of a 6/4 measure:

La cu-ca- | ra-cha, la cu-ca-ra-cha
| ya no pue-de ca-mi-nar
por-que no | tie-ne, por-que le fal-tan
| las dos pa- titas "de" a-trás.— ("The cockroach, the cockroach / can no longer walk / because she doesn't have, because she lacks / the two hind legs to walk"; these lyrics form the basis for the refrain of most later versions. Syllables having primary stress are in boldface; syllables having secondary stress are in roman type; unstressed syllables are in italics. Measure divisions are independent of text line breaks and are indicated by vertical bar lines; note that the refrain begins with an anacrusis/"pickup.")Many later versions of the song, especially those whose lyrics do not mention the cockroach's missing leg(s), extend the last syllable of each line to fit the more familiar 6/4 meter. Almost all modern versions, however, use a 4/4 meter instead with a clave rhythm to give the feeling of three pulses.

Verses
The song's verses fit a traditional melody separate from that of the refrain but sharing the refrain's meter (either 5/4, 6/4, or 4/4 clave as discussed above). In other respects, they are highly variable, usually providing satirical commentary on contemporary political or social problems or disputes.

Historical evolution
The origins of "La Cucaracha" are obscure. The lyrics of the refrain make no explicit reference to historical events, so it is difficult, if not impossible, to date them. However, because the verses are improvised according to the needs of the time, and mention contemporary social or political conditions, a rough estimate of their age can be made.

Pre-Revolution lyrics
Several early (pre-Revolution) sets of lyrics exist, referring to historical events.
In his book Cantos Populares Españoles (1883), Francisco Rodríguez Marín notes lyrics referring to the then recent Hispano-Moroccan War (1859–1860), which were probably developed by the troops during the campaign to boost their morale, using an existing melody:

Some early versions of the lyrics refer to the confrontation between Spanish and Moroccan troops (popularly referred to as "Moors" by the Spanish) during the Hispano-Moroccan War, that reflect Spanish popular imagery during their development from 1859 to 1860.One of the earliest written references to the song appears in the 1819 novel La Quijotita y su Prima, by Mexican writer and political journalist José Joaquín Fernández de Lizardi, in which it is suggested that:

Other early stanzas concern events such as the Carlist Wars (1833–1876) in Spain, and the French intervention in Mexico (1861).The period of the Mexican Revolution, from 1910 to about 1920, saw the first major period of verse production for "La Cucaracha", because both rebel and government forces invented political lyrics for the song. Many stanzas were added during that period, today associated mostly with Mexico.

Revolutionary lyrics
The Mexican Revolution was a period of great political upheaval, during which the majority of the stanzas known today were written. Political symbolism was a common theme in those verses, and explicit and implicit references were made to events of the conflict, major political figures, and the effects of the war on the civilians in general. Today, few pre-Revolution verses are known, and the most commonly quoted portion of the song are the two Villist anti-Huerta stanzas:
That version, popular among Villist soldiers, contains hidden political meanings, as is common for revolutionary songs. The cockroach represents President Victoriano Huerta, a notorious drunk who was considered a villain and traitor due to his part in the death of revolutionary President Francisco Madero.
Due to the multi-factional nature of the Mexican Revolution, competing versions were also common, including the Huertist, anti-Carranza stanza:

An example of two Zapatist stanzas is:

"La Cucaracha" was a popular tune among Mexican civilians at the time, and there are numerous examples of non-aligned political verses. Many were general complaints about the hardships created by the war, and were often written by pro-Zapatistas. Other non-aligned verses contained references to various factions, in a non-judgmental manner:

La Cucaracha as a woman
Soldiering has been a profession for women in Mexico since pre-Columbian times. Among the nicknames for women warriors, and camp followers, were Soldaderas, Adelitas, Juanas, and Cucarachas.Soldiers in Porfirio Diaz's army sang "La Cucaracha" about a soldadera who wanted money to go to the bullfights. In Mexican Military: Myth and History, Elizabeth Salas writes that, for the Villistas, "'La cucaracha' wanted money for alcohol and marijuana. She was often so drunk or stoned that she could not walk straight. Unlike corridos about male revolutionaries like Villa and Zapata, none of the well-known corridos about soldaderas give their real names or are biographical. Consequently, there are very few stanzas that ring true about women in battle or the camps."

Other verses
Apart from verses making explicit or implicit reference to historical events, hundreds of other verses exist. Some are new, and others are ancient, but the lack of references and the largely oral tradition of the song, makes dating the verses difficult, if not impossible. Some examples are:

Influences
In the novel Animal Farm by George Orwell, the animals' rebellion song, "Beasts of England", is described as a blend of the tunes of "La Cucaracha" and "Oh My Darling, Clementine".FC Utrecht has a long history of playing the tune at homes games after the team has scored.

Notes
References
External links
What are the words to "La Cucaracha"? on The Straight Dope
Version with several references to the Mexican Revolution
complete lyric 
Sheet Music for Wind Orchestra: Parts & Scores