Ah, summer. Sunshine, shirtsleeves, picnics, swimming, boating, hammocks, backyard grills and just goofing off.

But something else always enters the picture. There’s the cell phone call from I-95, “We’re coming.” The frequent apology that “We can stay only a week.” The casual remark that “We had to bring the dogs.”

Of course, we love them. And yet …

Just plain old friendship is part of the motivation. And it is so beastly hot in New York City and Philadelphia and their other regular haunts that the prospect of a vacation in the cool breezes of Maine sounds great. Free rent also may be a consideration. Plus the practical thought that it would be silly to come all this way for only a few days.

It is so easy in the long winter to suggest, even to bare acquaintances, that they might like to come up and see us sometime. That’s all it takes. Say that, and they will come. And it’s always in July or August. They are fair weather friends, whereas a visit in the midst of winter would be more welcome.

While some Mainers are totally hospitable, many have horror stories. There was the woman from away who fell on the bottom step just as she arrived, broke a leg and had to stay for weeks. Another unsuspecting hostess suggested that a visiting family might want to park their RV in the driveway. It turned out that the visitors had brought a dozen or so yapping little dogs for a dog show that lasted a week or so.

Another complained that so many relative strangers turned up that she had barely taken the bed linen off the line when the next batch showed up. She felt she was running a motel.

The classic response came from one of the offshore islands, as weeklong guests were about to board the ferry. The woman asked, “And can we come again next year?” The hostess replied: “No.”

Others have adopted a simple formula to callers angling for an invitation: “We would love to see you, and there are two lovely bed-and-breakfasts just down the road.”

Some wealthy summer residents of Northeast Harbor have a different solution. They have been buying up year-round residents’ houses and use them only in the summer to house their visitors. That is one factor in the 10-year decline in the village’s winter population from about 1,200 to the present 650 to 700.

Visitors would do well to help with the housework, entertain themselves at least part of the time and not overstay their welcome.

Generous Mainers should watch their generous mouths.