... “breeds fleas like a _loach_.”
Perhaps it is a misprint, or a provincial pronunciation, for “leach,” that
is, blood-suckers. Had it been gnats, instead of fleas, there might have
been some sense, though small probability, in Warburton’s suggestion of
the Scottish “loch.” Possibly “loach,” or “lutch,” may be some lost word
for dovecote, or poultry-lodge, notorious for breeding fleas. In Stevens’s
or my reading, it should properly be “loaches,” or “leeches,” in the
plural; except that I think I have heard anglers speak of trouts like _a_
salmon.