Superstition
When the farmer encounters the hireling standing naked in the moon, he immediately considers him to be doing some form of satanic worship. Without even thinking twice, the farmer shoots him and dumps his body in the river. There was no actual proof that the hireling was a warlock, and even the farmer notes that his body remains in human form when he gets rid of him. The farmer is clearly superstitious, which caused him to act without thinking things through.
Homosexuality
The farmer is described as a widow who works mostly alone on the farm. He seems eager to have a hireling working for him and quickly grows attached to him. Indeed, the night he catches the hireling, he takes note of his naked figure. In some ways, the farmer may have been repressing his homosexuality by killing the hireling as a means of removing the object of his desires. However, this does not work as thoughts of the hireling continue to occupy the farmer long after his death.
Folklore
The poem is set during the Irish tradition of the Lammas Harvest. The farmer is clearly a devout believer of the myths and legends he grew up with as he is quick to label the hireling as a warlock that turns into a hare. Indeed, he even suggest that his cows have been contaminated through the hireling’s touched, "my herd's elf-shot”, as the Irish myth describes shooting pains being caused by invisible elves firing invisible arrows.
