Albert Barnes Commentary Ecclesiastes 10:1

"Dead flies cause the oil of the perfumer to send forth an evil odor; [so] doth a little folly outweigh wisdom and honor." — Ecclesiastes 10:1 (ASV)

This verse is by its meaning so closely connected with (Ecclesiastes 9:18) that the selection of it for the beginning of a new chapter seems unfortunate.

Apothecary – Rather: a dealer in spices and perfumes . The swarms of flies in the East very soon corrupt and destroy any moist ointment or mixture left uncovered, and pollute a dish of food in a few minutes.

So doth... – literally, more weighty than wisdom, than honor, is a little folly.