Secondly, rearing a large number of Demon Insects requires the consumption of an immense amount of resources, far more than what is needed to support a Demon Beast, and much greater at that.
Third, apart from some extremely rare and unusual strange insects, the strength of the vast majority of Demon Insects is not too great.
Even those Demon Insects carefully cultivated by Golden Core Stage Cultivators from the Thousand Spirit Sect are hardly able to withstand the power of Dharma Treasures.
In battles against Cultivators of the same realm, barely any Golden Core Stage Cultivator from the Thousand Spirit Sect can claim victory solely by using Insect Expelling Techniques.
The same goes for them, no matter how many insects they breed!
Similarly, Demon Insects that pose a threat to Nascent Soul Stage Cultivators essentially only exist within certain records of the Thousand Spirit Sect, and the vast majority of them have long been declared extinct.