We need a verb to describe what the bumblebee is doing on the flower.
Here are some possibilities:
* is - The bumblebee is on the flower.
* sits - The bumblebee sits on the flower.
* buzzes - The bumblebee buzzes on the flower.
* collects - The bumblebee collects nectar from the flower.
Let me know if you'd like to complete the sentence with one of these verbs!