As I discuss in this question, by far the most popular school of Hindu philosophy is the Vedanta school, which bases its tenets on the doctrines laid out in the Brahma Sutras, a work by the sage Vyasa which summarizes and systematizes the philosophical teachings of the Upanishads. (You can read the Brahma Sutras here.) In any case, in Adhyaya 2 Pada 1 Sutra 6 of the Brahma Sutras, Vyasa says this:
But it is seen.
Let me explain what this means. One of the tenets of the Vedanta school is that Brahman is both the material cause and the efficient cause of the Universe, i.e. both the source and the operator of the Universe. But an objection is raised, how can Brahman be the source of the Universe of Brahman is conscious and the Universe is unconscious? For don't conscious entities only emerge from conscious entities (like a child emerging from its mother) and unconscious entities only emerge from unconscious entities (like sparks emerging from a fire)? Vyasa responds that actually it is seen in real life that sometimes you have cause-and-effect situations where one thing is conscious and the other thing is unconscious. Here is what the Advaita commentator Adi Sankaracharya says in his commentary on this Sutra:
Your assertion that this world cannot have originated from Brahman on account of the difference of its character is not founded on an absolutely true tenet. For we see that from man, who is acknowledged to be intelligent, non-intelligent things such as hair and nails originate, and that, on the other hand, from avowedly non-intelligent matter, such as cow-dung, scorpions and similar animals are produced.
And here is what the Sri Vaishnava commentator Ramanujacharya says:
The 'but' indicates the change of view (introduced in the present Sûtra). The assertion that Brahman cannot be the material cause of the world because the latter differs from it in essential nature, is unfounded; since it is a matter of observation that even things of different nature stand to each other in the relation of cause and effect. For it is observed that from honey and similar substances there originate worms and other little animals.--But it has been said above that in those cases there is sameness of nature, in so far as the relation of cause and effect holds good only between the non-intelligent elements in both!--This assertion was indeed made, but it does not suffice to prove that equality of character between cause and effect which you have in view. For, being apprehensive that from the demand of equality of character in some point or other only it would follow that, as all things have certain characteristics in common, anything might originate from anything, you have declared that the equality of character necessary for the relation of cause and effect is constituted by the persistence, in the effect, of those characteristic points which differentiate the cause from other things. But it is evident that this restrictive rule does not hold good in the case of the origination of worms and the like from honey and so on; and hence it is not unreasonable to assume that the world also, although differing in character from Brahman, may originate from the latter. For in the case of worms originating from honey, scorpions from dung, &c., we do not observe--what indeed we do observe in certain other cases, as of pots made of clay, ornaments made of gold--that the special characteristics distinguishing the causal substance from other things persist in the effects also.
And for good measure, here is what the Shaiva Siddhanta commentator Srikantha Shivacharya says:
Though distinct in their nature, Brahman and the universe can be related as cause and effect, because the sentient scorpion is seen to take its birth in insentient cow-dung, and that the insentient hair is found growing out of sentient man. Hence the conclusion that mere unaided reasoning cannot prevail against the exegetical interpretation of the sruti.
So my question is, what scriptures say that scorpions can be born from cow dung? Because it seems to have been common knowledge in ancient India.
EDIT: It looks like it's not just Vedanta philosophers who talk about scorpions born from cow-dung; here's what the Kashmiri Shaivite philosopher Abhinava Gupta says in this excerpt from his commentary on Bharata's Natya Shastra:
From some particular scorpions, for instance, it is legitimate to infer that their cause is cow dung; and the inference, from them, of another scorpion, as their cause, would be nothing but a false cognition.