Hebrew word · H6157

עָרֹב

aro

swarm

Appears only for this plague (Exod 8:21–31; Ps 78:45; 105:31). Most connect it with the root ʿ-r-b, 'to mix, mingle', so the word means a teeming, mixed mass, a swarm. What exactly the swarm was is not stated.

Appears 9 times in 7 verses of the Hebrew Old Testament. ·

What it means

1) swarm

1a) probable meaning from 'mixture' and 'incessant or involved motion'

Abridged from Brown, Driver and Briggs, A Hebrew and English Lexicon of the Old Testament (1906), via STEPBible.org (CC BY 4.0).

In depth

From the study of Exodus 8:22

Range of meaning

Appears only for this plague (Exod 8:21–31; Ps 78:45; 105:31). Most connect it with the root ʿ-r-b, 'to mix, mingle', so the word means a teeming, mixed mass, a swarm. What exactly the swarm was is not stated.

Against the English

KJV prints 'swarms [of flies]', with 'of flies' in italics as words the translators supplied. Most modern versions drop the signal and simply say 'flies'. YLT's 'beetle' reflects a theory that the scarab beetle was meant.

How it drifted

English translations follow the Greek 'dog-fly' reading, but they present as fact a detail the Hebrew leaves open.

Used elsewhere in the period

LXX: kynomyia, 'dog-fly', a biting fly. Philo (Life of Moses 1.130–133) describes the dog-fly as an especially vicious creature that combines the boldness of a dog with the persistence of a fly. Ps 78:45 says the ʿarov 'devoured' the Egyptians, which suggests biting creatures. Rabbinic tradition (Exodus Rabbah 11; Rashi on Exod 8:17) reads it as 'a mixture of wild beasts': snakes, scorpions and wild animals.

From the study of Psalm 78:45

Range of meaning

A rare word, found only in Exodus 8:21–31 (Hebrew 8:17–27), Psalm 78:45 and Psalm 105:31. Standard lexicons (BDB, HALOT) give 'swarm', usually understood as a swarm of flies or other stinging insects, and note that the exact creature is unknown. Its origin is disputed. Many connect it with the root ʿ-r-b, 'to mix', which gives the ancient reading 'mixture'. Others take it simply as the word for a teeming mass.

Against the English

BSB, WEB, NIV, ESV and NASB all have 'swarms of flies'. Note that 'of flies' is an interpretation; the Hebrew has only the one word. The KJV's 'divers sorts of flies' combines the insect reading with the 'mixture' idea (via the Latin 'every kind of fly'). Young's Literal Translation has 'the beetle', reflecting a 19th-century guess (sometimes linked to the Egyptian scarab) that has not won acceptance.

How it drifted

The English plural 'flies' makes modern readers picture houseflies, which annoy but do not hurt. The ancient Greek translators chose 'dog-fly', a biting, blood-drawing fly. That is why the psalm can say the swarm 'ate' people.

Used elsewhere in the period

The Greek Septuagint translates it κυνόμυια (kynomyia, 'dog-fly') both in Exodus and in this psalm (LXX Ps 77:45). Philo of Alexandria (Life of Moses 1.130–131) takes this up, describing the dog-fly as combining the dog's boldness with the fly's persistence. Josephus (Antiquities 2.303) instead describes all kinds of wild beasts afflicting Egypt. Later rabbinic interpretation (e.g., Exodus Rabbah, Rashi) likewise reads ʿārōv as a 'mixture' of wild animals. Psalm 105:31 pairs ʿārōv with kinnim (gnats or lice), which suggests the psalmists thought of insects.

From the study of Exodus 8:21

Range of meaning

A rare noun, found only in the account of the fourth plague (Exod 8) and in two psalms that retell the plagues (Ps 78:45; 105:31). In context it is a mass of living creatures that fills houses and covers the ground. Psalm 78:45 says the 'arov 'devoured' the Egyptians, so it probably bit or stung. Lexicons (BDB, HALOT) give 'swarm' and admit the exact creature is unknown. The word looks related to the root 'rv, 'to mix', so some have taken it to mean a mixed horde.

Against the English

Most English versions say 'swarms of flies' (KJV, BSB, WEB, NIV, ESV, NLT). 'Of flies' is an explanatory addition, and KJV prints it in italics to show it is not in the Hebrew. NASB and some Jewish translations say 'insects'. Young's Literal Translation says 'the beetle'. The Hebrew has one word, singular and with 'the' ('the swarm'), and it names no particular insect.

How it drifted

English translations took their 'flies' from the Greek Septuagint's 'dog-fly' and the Latin Vulgate's 'every kind of fly'. Over time 'flies' became settled in English, and readers now picture ordinary houseflies, a certainty the Hebrew does not give.

Used elsewhere in the period

The Septuagint (3rd century BC) translates it kynomyia, 'dog-fly', and does the same in the psalms. Philo of Alexandria (On the Life of Moses 1.130–132) describes the dog-fly as a fierce biter and explains the name. The Vulgate has omne genus muscarum, 'every kind of fly'. This combines the 'fly' reading with the 'mixture' idea. Rabbinic tradition (Exodus Rabbah; Rashi) reads it as a mixture of wild beasts, from 'rv 'mix'. Josephus also speaks of creatures of many kinds. A modern natural-cause theory (Greta Hort, 1957–58) suggests the biting stable fly, Stomoxys calcitrans.

Where it appears

Exodus · 7

  1. Exodus 8:21 הֶעָרֹ֑ב הֶ֣עָרֹ֔ב the swarm

    But if you will not let My people go, I will send swarms of flies upon you and your officials and your people and your houses. The houses of the Egyptians and even the ground where they stand will be full of flies.

    Here: 'The swarm.' The word is rare and nobody knows exactly what creature it names. Early Greek translators thought it was a biting 'dog-fly'. Rabbinic tradition linked it to the root 'mix' and read it as a mixture of wild creatures. Hebrew does not say 'flies'.

  2. Exodus 8:22 עָרֹ֑ב a swarm

    But on that day I will give special treatment to the land of Goshen, where My people live; no swarms of flies will be found there. In this way you will know that I, the LORD, am in the land.

    Here: The fourth plague. Hebrew does not say 'flies'. The word is linked to a root meaning 'mix', so it means a swarm or teeming mass of some kind. The Greek translators understood it as a biting 'dog-fly', and some Jewish tradition took it as a mixed horde of wild animals.

  3. Exodus 8:24 עָרֹ֣ב הֶעָרֹֽב׃ a swarm, the swarm

    And the LORD did so. Thick swarms of flies poured into Pharaoh’s palace and into the houses of his officials. Throughout Egypt the land was ruined by swarms of flies.

  4. Exodus 8:29 הֶעָרֹ֗ב the swarm

    “As soon as I leave you,” Moses said, “I will pray to the LORD, so that tomorrow the swarms of flies will depart from Pharaoh and his officials and his people. But Pharaoh must not act deceitfully again by refusing to let the people go and sacrifice to the LORD.”

    Here: The fourth plague. The noun names a swarm or teeming horde but does not say which creature. Most translations say 'flies'. The Greek translation says 'dog-fly', a biting fly. Jewish tradition took it as a mixed horde of wild animals.

  5. Exodus 8:31 הֶעָרֹ֔ב the swarm

    and the LORD did as Moses requested. He removed the swarms of flies from Pharaoh and his officials and his people; not one fly remained.

Psalms · 2

  1. Psalm 78:45 עָ֭רֹב a swarm of flies

    He sent swarms of flies that devoured them, and frogs that devastated them.

    Here: The name of the fourth Exodus plague. The word appears only in Exodus 8 and Psalms 78:45 and 105:31, and what it refers to is uncertain. The Greek translation and the pairing with gnats in Psalm 105 point to biting insects. Later Jewish tradition read it as 'a mixture' of wild animals. It is singular in form, meaning one massed swarm or horde.

  2. Psalm 105:31 עָרֹ֑ב a swarm of flies

    He spoke, and insects swarmed—gnats throughout their country.

    Here: The fourth plague of Exodus 8. What exactly it was is unclear. Most likely it means a swarm of biting flies; the Greek translators called it "dog-fly." Some ancient Jewish interpreters read it as "a mixture" of wild animals. The word appears only here, in Psalm 78:45, and in Exodus 8.

Word data: STEPBible.org (CC BY 4.0), main text only.