In the heart of the capital, the captured Insect King was not immediately put to work causing havoc; it was instead secretly bred in captivity.
The timing was not right, with summer soon coming to an end. It was clearly not a good time to cause a locust plague. Keeping it for a year to become strong and healthy would surely result in a much better outcome when it was finally released.
However, it was slightly cruel for the Insect King. As a captive, the upcoming year would be spent in the wizards' laboratory.
Many methods exist to artificially mature magical beasts, most of which have side effects. For Contracted Magic Beasts, such drastic measures couldn't be used at all.
Using them on the Insect King, however, was a different matter. The journey from being an Insect King to becoming an Insect Emperor was long, and the success rate was pitifully low.