I was watching a television show called "Museum Secrets" that showed some of the permanent collection from the Neues Museum in Berlin. My interest was piqued by the 'Berlin Gold Hat' pictured here, courtesy of Wiki Commons. The commentator stated that the hat was a solar/lunar calendar and was used in honey production to know when the solstice in June was near. It was stated that bees were affected by the full moon in June, this was when the hive would have maximum honey and this is why marriages are followed by the 'honey-moon' - maximum sweetness.
This put several questions in my mind which are challenging to resolve in a few hours of casual research.
Is the June full moon actually called the 'honey moon'? In some cultures, yes.
The solstice celebration is also the feast of St. John the Baptist. In spite of what some websites say, he is not the patron saint of bees. St. Ambrose is because of a story in the Legenda Aurea about a swarm of bees and that he also compared the church to a hive of bees.
When did people start having honeymoon trips? According to the Oxford English Dictionary, the first use of 'honeymoon' as the post marriage bliss was in 1546 in J. Heywood's book on proverbs in the English tongue and refers to the moon that is full but it doomed to wane like people's affections. The honeymoon did not come into style until the late 18th or early 19th century. Wikipedia is my source for saying that, as the British moved into India, the Indian custom of a post-marriage bridal tour became the fashion. There are no references to a honeymoon tour before 1821 in the OED.
The word 'honey' comes from the Germanic languages and is hunig or hunæg in Old English. There is no honey-month or honey-moon in the Anglo Saxon dictionaries. June was called Liða by the Venerable Bede.
From Bulletin 489, from the U.S. Department of Agriculture, "It is possible that the custom of killing the bees and taking the honey in the full moon in June may result in a smaller amount being secured that if the killing were left until gathering had ceased in the fall."
When did it become the custom to have marriages in June? I am not sure. It is likely a modern invention because people got married any old time although, in the Middle Ages, high feasts seemed like a favorite time. As well, many people did not actually get formally married by a priest because many of the small villages lacked priests.
So you see, it is complicated. And so, I shall leave this with a quote from Brewer's Guide to Phrase and Fable: "a holiday spent together by a newly married couple. The word was originally used for the first month of marriage, although 'moon' does not mean the 'month' here, as sometimes supposed. The reference is to the moon as sweetness and is ironic, for no sooner is it full than it begins to wane." Indeed.