What are some themes of Roald Dahl's "Royal Jelly"?

While the themes of this short story by Roald Dahl can be difficult to identify, there are two which are the most evident. First, it is clear that the father loves the baby very much, which is why he begins to experiment with feeding the undernourished child royal jelly. At first, it seems to have only a positive, nourishing effect on the child, but then as time goes on, the baby seems to be morphing into a sort of larvae-like version of her former self. The mother loves the child as well, which is why she nurses a healthy skepticism for how the father is going about taking care of the child. She doesn't want anything to happen to her and because she feels that she doesn't know enough about this "treatment," she can't really say if it's the best thing for her child. This disparity in the way that the mother and father express their love and concern for the child leads us to identify this theme: that two people can express love for someone in very different ways, and it is often impossible to know who is in the right. 

Toward the end of the story, the mother begins to take a closer look at both her husband and child. She realizes the toll that this royal jelly fanaticism has taken on both of them. Her husband's shape has a peculiar bee-like quality to it and he's sprouted dark hairs, and her daughter has become very chubby and cherubic, just like a little grub. At first, they had both seen positive benefits from the use of the jelly. The husband used it to treat his infertility, which is how his daughter was conceived, and the daughter had begun to be healthy again because of the nutrients found in the jelly. Over time, however, the husband began to increase the amount of the jelly until he was giving large quantities of it to his daughter, and that is when the wife began to become estranged from them. This leads me to the next theme of the story, which is that too much of a good thing can sometimes have negative effects. This could be love, it could be devotion, and it could be material things or food.