Final answer:
The repetition of 'load on load of apples' in Frost's poem is an example of the literary device known as repetition, highlighting the ample harvest and the speaker's fatigue.
Step-by-step explanation:
In the excerpt from Robert Frost's After Apple Picking, the poetic device employed in the repetition of the phrase load on load of apples is repetition. Repetition is a commonly used literary device that involves intentionally using the same words or phrases multiple times to emphasize a particular concept or theme. Frost's use of repetition helps to convey the abundance of the harvest and the weariness of the speaker.