Final answer:
Treatment for hypoderma should occur after fly season ends and before larvae migrate to prevent hide damage, typically in late fall or early winter, following veterinary advice.
Step-by-step explanation:
Treatment for hypoderma, also known as cattle grub or heel fly infestation, should be administered after the end of the fly season and before the larvae migrate to the back of the cattle, which is usually in the late fall or early winter. This is to prevent the larvae from reaching the stage where they cause hide damage and other health issues in the cattle. It is essential to follow a veterinarian's advice on treatment protocol to ensure effectiveness and avoid resistance development.