Moonlight in Edward Thomas's poem does not stop at the obvious beauties. It also finds a jar hanging from a tree, a thing put out to catch wasps, and makes it as brilliant as anything in the sky. That small event is the whole of "The Wasp Trap". Its central idea is that loveliness is not a fixed property of lovely things. Light can lend it to almost anything, and an observant, generous eye can notice when it does.
The first two stanzas are the hardest part, and they are meant to be. The poem begins with a safe claim: moonlight makes "the lovely lovelier / Than ever before lakes / And meadows were." Then it turns on itself. "And yet they are not," the second stanza says, "more / Lovely than things that were not / Lovely before." Put plainly, in moonlight the famous beauties are no more beautiful than things nobody thought beautiful until now. The syntax feels like someone thinking aloud and qualifying as he goes ("And yet", "Though this their hour is"). Even the rhyme is awkward at this point, because "not" rhymes with itself, so the negation is hammered home. The stanza also carries a quiet reminder that this is only "their hour". The beauty is temporary.
Notice what the poem withholds. The word "lovely" appears four times in the first two stanzas and then disappears. It is an abstract, rather worn word, and the poem replaces it with sensory ones: "pure brightness", "star", "glistening". Having spent two stanzas on a loose idea, it settles on something you could actually see. The reveal comes with "that jar". After the sweeping "Nothing on earth, / And in the heavens no star", this flat little monosyllable lands like a pointing finger. It also rhymes with "star", so the sound sets the two side by side before the sense does.
The word "worth" matters too. It is the language of valuation, and the poem uses it to say that, judged purely on "brightness", a trap for pests outranks everything on earth and in the heavens. The last stanza makes the shift in purpose explicit: "For wasps meant, now / A star." The clipped phrase "for wasps meant" states what the jar was made for, and "now" falls at the end of the line like a hinge between that purpose and what it has become. The poem never says what the jar contains. Judging by the title and the phrase "for wasps meant", it is a trap, so something unpleasant is presumably inside. Only its shine is shown.
The setting adds to the effect. The jar swings "From the dead apple-bough", and that dead wood, together with a device made to kill, gives the scene a bleak edge. The brightness stands out against it. "Long may it swing" is a strange, affectionate wish, almost a toast. The verb "swing" gives the star a motion that suits glass catching light, and the wish admits that this glory cannot last. The poem ends on "So glistening", a three-syllable word that trails off and lets the shine linger.
Structurally, the poem is four quatrains rhymed ABAB. The first and last lines of each stanza are short and the two middle lines longer, so each stanza swells and then closes. Most of the rhymes are full ones (makes/lakes, earth/worth, star/jar, now/bough). A few are looser, like lovelier/were and swing/glistening, which keeps the tidy pattern from sounding too neat. The diction is plain throughout, and "star" is the only real metaphor. Because the poem has been so unadorned, that one figure feels earned rather than decorative.
That restraint is what makes the poem worth reading. It would be easy to write a poem praising the moonlit lake. It is harder, and more surprising, to argue that a utilitarian object on a lifeless branch deserves the same praise, and to do it without sentimentality. The poem suggests that beauty depends on attention and circumstance more than on rank. For a few hours the jar is a star, and the poem's job is to see it before the light moves on.