When I finally get around to writing my “Parenting for Dummies” book, I’ll be sure to devote a chapter to what you can expect when the family vacations finally end.

It is a curious phenomenon of sorts, one that affects just about every family at some point in its evolution. You might even call it a milestone in the maturation of a parent, ranking right up there with the experience of ushering a nervous daughter to the first day of kindergarten or dropping off a son on a campus hundreds or thousands of miles from home. And like most of the transitional moments of parenthood, the inevitable winding down of the family vacation comes without warning. It just happens, naturally, in its own time. It is the end of something good, though you can never be prepared when it hits. One summer you’re busily loading up the family buggy with suitcases, sleeping bags and bicycles for that precious week or two together, as you’ve done since the kids were small, and the next summer you’re sitting alone with your spouse and wondering how it all passed so quickly out of your life.

How did the kids manage to grow up so fast? When did those sleepy, sunburned faces in the back seat turn into fledgling adults whose impossibly hectic social lives and work schedules one day forced an abrupt end to that cherished yearly ritual when the family pulled away from the rat race for a spell to simply be together to laugh and play in the sun?

Having just gone through this parental transition, this break in an intimate and happy tradition that I had foolishly assumed was inviolate, I admit to a sense of loss. When I first learned that we would not be able to take our usual trip to the seashore this year, I struggled to find a comparably enjoyable way to fill my two-week vacation. Alternative plans were hatched and quickly discarded as impractical. So the first week I loafed around the house, fiercely resisting the nagging impulse to undertake any of the 100 domestic projects that I hadn’t gotten around to.

“This is the lousiest vacation I’ve ever had,” I complained to my wife, who shrugged helplessly as she headed out the door to work.

The second week, in a desperate bid to salvage some measure of fun from this oddest of vacations, we rented a cozy cabin on a lake just a few miles from the house. Despite having an outhouse and no running water, the cabin did at least offer a change of scenery that might allow us to feel as if we’d actually gone somewhere. It would have, too, had we been able to spend at least one full, leisurely day there. Instead, we drove back and forth to Bangor three or four times daily, shuttling one of our two busy teen-agers to driving school, morning and evening soccer practices and assorted social functions. The other one shuttled himself, which left us to hear the loons at night with one ear while listening with the other for the sound of his car in the night.

“Every parent has to go through this change,” counseled one veteran mother, who said it took her several years to fully relinquish the hope that she and her family could ever again duplicate the carefree, close-knit summer vacations they once knew. She tried on occasion, but it never worked. Her teen-age children were either too busy or had more exciting ways to spend their vacation time. She eventually learned to accept the change as a preparation for the empty nest to come.

“So you roll with it, make new vacation plans that don’t necessarily include the children anymore, and enjoy the wonderful memories,” she said. “Eventually, it all comes back around again.”

I asked her when that might be.

“When you become a grandparent,” she said.