In the limerick, above the rhyming of lines 3 and 4 does not fit in with the scheme of lines 1, 2, and 5.

Not quite sure I understand you. None of the lines in the poem rhyme: Bees, wasp, hurt, doesn't, or hornet. The number of syllables per line does vary a bit: 9 or 10 and 6 or 7.

Ceci n'est pas un seing.