What action is usually necessary for this rear-fanged snake to successfully inject venom into prey?

Answer

Chewing or holding on for a longer duration

Because the fangs are located in the back of the jaw (opisthoglyphous dentition), the snake usually has to chew or hold onto its prey for a longer duration than front-fanged snakes to successfully inject venom.

What action is usually necessary for this rear-fanged snake to successfully inject venom into prey?
venomreptilesnake