The noun coccinellid denotes a beetle of the family Coccinellidae. The genus name Coccinella is from Latin coccineus, scarlet (the word cochineal, a scarlet dye, has the same origin). This family includes the ladybirds (ladybugs in American English). The scientific name of the common European seven-spot ladybird is Coccinella septempunctata (septempunctata = seven-spotted).
The word lady is from Old English hlǣfdige, literally kneader of bread, a compound of hlǣf, loaf, and -dige, kneader, related to dough.
The weak genitive singular hlǣfdīgan (lady’s) became by regular phonetic change coincident in form with the nominative (lady). This is the origin of compounds that appear to be attributive but are in fact genitive, such as Lady chapel, a chapel dedicated to the Virgin Mary, Lady Day, the feast of the Annunciation on 25th March, and ladybird in the sense of the small beetle. (The Virgin Mary was usually named Our Lady, which translates Latin Domina Nostra – cf. French Notre Dame.)
(The obsolete compound ladybird used as a term of endearment is not genitive but attributive; in An excellent conceited Tragedie of Romeo and Iuliet (Quarto 1, 1597), by the English poet and playwright William Shakespeare (1564-1616), Juliet’s nurse exclaims “what Lamb, what Ladie bird”.)
The name ladybird applied to the beetle is first recorded in 1674. It was so named on account of its seven spots, which were popularly believed to symbolise the seven sorrows of the Virgin Mary. These seven sorrows are Simeon’s prophecy*, the flight into Egypt, the three days’ loss of the child Jesus in the Temple, the meeting of Jesus and Mary on the way to the Cross, the Crucifixion, the taking down of the body of Jesus from the Cross, the burial of Jesus.
* gospel of Luke, 2:34-35 – King James Version (1611):
34 And Simeon blessed them, and said vnto Mary his mother, Beholde, this child is set for the fall and rising againe of many in Israel: and for a signe which shall be spoken against,
35 (Yea, a sword shall pearce thorow thy owne soule also) that the thoughts of many hearts may be reuealed.
Earlier English names were ladycow and its transposition cow-lady. The terms bishop and golden knop were also used.
Similar names of the beetle are widespread in other European languages. For example, French used bête de la Vierge (bête = animal, insect), vache à Dieu (vache = cow) and still uses bête à bon Dieu (bon Dieu = good Lord). However, ladybird translates as coccinelle in standard French.
Likewise, German has Marienkäfer, Mary’s beetle, and Herrgottskäfer, the Lord God’s beetle.
Portuguese has joaninha, a diminutive of the proper name Joana, and vaquinha, a diminutive of vaca, cow. Catalan uses marieta and Spanish mariquita, diminutive of marica, itself a diminutive of María (similarly, Spanish mariposa means butterfly).
Among other names, Romanian uses boul-lui-Dumnezeu and boul-Domnului, the Lord’s ox, vaca-Domnului, the Lord’s cow, găina-lui-Dumnezeu, the Lord’s hen.
The Volkswagen beetle (bug in American English) is coccinelle in French, Käfer in German, escarabajo (beetle) in Spanish, maggiolino (cockchafer) in Italian, carocha (beetle) in Portuguese.