What is the meaning of “Fly pleasures, and they’ll follow you”?

Hmmm. It is not clear to this native English speaker. The general sense is, but not the specific meaning of "fly pleasures".

My guess (and it is only a guess) is that this is a reference to hawking - hunting with hawks or other birds. The OED give as definition 3c for fly: "To chase with a hawk", which is not on the surface a particularly good fit. But when a hawker flies a bird, they let it go (to chase prey), confident that they have trained it to return to them. I take it therefore that it means "Let pleasures have some freedom, to soar in the air, and they will come back to stay with you".

From Wisdom from B Franklin

Industry gives comfort and plenty and respect: fly pleasures, and they’ll follow you. If we work as we should, then we will have all that we need. If you take the proper time for pleasure, then it can be properly enjoyed.

And from the etymology fly = flee: etymonline

fly (v.2)

"run away," Old English fleon, flion "fly from, avoid, escape;" essentially a variant spelling of flee.

and

perhaps from fly (n.) on the notion of the insect being hard to catch

Thus possibly: let go of (flee) pleasure, pursue industry (work and toil), and pleasure will follow!