Unlike the ancient Egyptian religion, where serpents, snakes, frogs, crocodiles, flies, rats, and a host of other creatures were worshipped; the ancient Aryan looked upon many of these creatures as hideous, grotesque, monstrous and malformed freaks of nature.
To the ancient Aryans, ants, serpents, frogs, worms, flies and rats meant only death, pestilence, and omens of impending evil.
In the Avestan lore, most worshipped creatures of the ancient Egyptian religion and Mesopotamia are seen as noxious, misshapen, repulsive and demonic creatures. The fabulous beasts of the Mesopotamian mythology and most of the worshipped animals of the ancient Egypt were seen as foul, mutated, monstrous, malformed versions of life by the ancient Aryans.
For example in ancient Egypt flies were emblems of valor and persistence and the king awarded gold flies of valor to distinguished warriors. Also the flywhisk is symbol of authority in African folk religion.
NOT SO, in the Avesta and among the ancient Aryans. Flies (magas) midges, mosquitoes, locust, Lice, and fleas symbolized only death disease, pestilence, and corruption in the Avesta.
(The word for flies magas/ magass is the same as Latin musca, Sanskrit. maksa-, Greek. myia, Old Church.Slavic. mucha, Old.English. mycg, English midge.)
The Avestan word for ants and/or termites is mür literally “mors, death, destruction.”
In the Avesta snakes and serpents are called marthra or “murderer” compare with German Mord and English murder, Persian maar. They are the emblems of evil, deceit and chaos.
While in the south Indian Dravidian beliefs and the Chinese mythology; rats are considered auspicious and holy. In Zoroastrianism; rats, mice (müš) and/or other infestation causing rodents are symbols of disease, avarice, greed, and deformed, destructive intelligence.
The identification of frogs with heresy, forgery, and unclean spirit in the book of revelation (16.13) seem to be a direct Zoroastrian influence and/or borrowing.
Herodotus (1.140) reports that the Zoroastrian Magi customarily killed ants, snakes, rats and flies/midges.
In traditional Zoroastrianism, pest control (i.e., “destroying noxious creatures/vermin”) is considered the “bounden duty of the faithful” (refer to Yasht. 21.1, and Vendidad.16.12.) Its importance is reflected in the old annual celebration of the Feast of pest killing (Jašn-e ḵkrafstra koshuun) by the Zoroastrians of Kerman, which used to be held at the beginning of summer.
In the Avestan lore, destructive pests that bring about infestation, disease and doom with them are called khrafstar or khrafβtar.
Khrafstar(s) or khrafβtar(s) are considered stagnant life forms. They belong to a bygone era and have stopped progressing. Hence, they are limited, stagnated, parasitic and very deadly. All creatures that stop to evolve and progress have no further place in the creation according to the Zoroastrian lore. I
In the poetic gathas of the Aryan Prophet, the term khrafstar/ khrafβtar means simply “Monster” and comes with other terms such bestial, demons and mortal men. The term khrafstar/ khrafβtar in the poetic gathas does not necessarily apply to pests and noxious creatures; but does refer to malignantly clever, yet deformed intelligences of grotesque creatures.
The term khrafstar or khrafβtar appears 3 times in the poetic gathas and in all 3 instances has been translated as “khiradö staredö” or “a scattered, misshapen and deformed power of manifestation or wisdom.”
In the third rhymed verse line, second stanza of Yasna 34.9, the designation khrafstar/khrafβtar comes right after bestial creatures or aúrúná, (Compare Avestan aúrúná with the old Norse rune uruz “wild beasts.”)
In the third rhymed verse line, second stanza of Yasna 34.5, the term khrafstar/ khrafβtar comes after daævá/demonic powers and before mashyá/marthyá or mortals.
In the third rhymed verse line, second stanza of Yasna 28.5, the ancient Aryan Prophet prays to bring monsters of malformed intelligence under his will power (vauröi-maidi literally “bring under my will”) through this most magnificent manthra (mind formula).
The idea of diverting khrafstars to advantage and benefit is inspired by the above rhymed verse line of Yasna 28.5.
Hence, in the poetic gathas, khrafstars or monsters or are not unconditionally evil, but a mutant intelligence/wisdom that with mind-power formulas can be diverted to the benefit/advantage of creatures of this creation; just as the bee which prepares honey, the worm from which there is silk …”
So in the Gathas Yasna 34.9 shows the link between khrafstars and beasts, Yasna 34.5 shows the link between khrafstars and both daevas and people as harmful intelligences, and Yasna 28.5 shows we can divert khrafstars to do good.
As people, and daevas for that matter, who become khrafstars are not unconditionally evil so are the beasts who become khrafstars.
The killing of animals classified as khrafstars in Zoroastrian tradition is a subject I have had difficulty with understanding but disease, infestation, and general harmfulness to people do seem to be the main concerns which is what I thought. What the Gathas say about this helps me to understand the issue much better. I especially like what Yasna 28.5 says which I think is a positive message.
Also as Mesopotamian myth and art feature monstrous creatures so does the neighboring Elamite art. Ancient Elam was closer to Pre-Achaemenid Iran.