This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
蠊 combines 虫 (insect) with 廉, which likely contributes sound. The exact historical development is uncertain.
The insect radical 虫 suggests a bug, but the overall meaning is unclear. Think of it as a mysterious insect whose name is lost.
For レン, imagine a lens used to examine a rare insect: lens -> レン, and the insect radical 虫 hints at the bug under the lens.
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Rhabdoblatta yayeyamana (species of cockroach)
harlequin roach (Neostylopyga Rhombifolia); harlequin cockroach
Surinam cockroach (Pycnoscelus surinamensis)
Rhabdoblatta guttigera (species of cockroach)
Blattella nipponica (species of cockroach)
Eucorydia yasumatsui (species of cockroach)
giant burrowing cockroach (Macropanesthia rhinoceros)