FORESTVILLE — Ilaissa and Thalia Negron agreed that summers in Forestville are cooler than those in New York City. Especially when you're on the Slip 'n Slide.

It's the girls' favorite activity when visiting the home of Susan and George Holtz, their Fresh Air Fund hosts for the summer. This year's two-week visit was the sixth for Ilaissa, 11, and the second for Thalia, 9.

The Holtzes, who also have five children of their own, tried to fill the visit with lots of activities, including trips to the Pittsburgh Zoo, Children's Museum, the Alameda Park pool and the Pioneer Drive-In. In past years they've also traveled to Idlewild Park, which both girls list as a favorite trip.

But the girls love the days at home with the Slip 'n Slide almost as well as any trip.

"We do that daily," said Ilaissa, pointing to the muddy strips parting the grass on the lawn.

The pair also enjoys playing in the nearby cornfield, creating their own maze among the stalks. For the first few years Ilaissa visited, she would assume every cornfield she saw was close to the Holtzes' home, said Susan.

Home for the sisters is an apartment in Brooklyn, where they live with their parents, brother and new baby sister, born in February. There's no yard or grass nearby to play in, according to Ilaissa.

"I like the beautiful sights here, like the view and the big open fields," she said. "There's more room for air to move and less buildings."

The Holtzes own 40 acres near Forestville in Mercer Township, including a large yard surrounded by the cornfields and a long driveway for bike riding — another favorite activity of the sisters.

They've had plenty of first experiences during their visits, like sitting by a campfire toasting S'mores, feeding a neighbor's horses or watching someone mow the lawn.

Ilaissa learned to swim in deep water this summer. Thalia was surprised by the first tornado warnings she'd ever experienced.

The pair, who return to New York City on Saturday, also learned some dislikes during their visits.

"I'm not a fan of bugs," said Thalia.

When the Holtzes first hosted Ilaissa at age 5, they did it to keep their grandchildren company. It wasn't until a year later that they adopted their first child, 16-month-old Kayleen, now 5, from China. Since then, their family has grown each year by adoption, including Timmy, 6, Rebekah, 9, Logan, 9, and Daniel, 11. The Negron girls said they aren't always sure what to expect with each return visit, but they enjoy being part of the big family.

Overall, the kids get along, though they do have their moments of conflict. Rebekah, the latest to join the Holtz family, didn't enjoy sharing one of the swings with Thalia one evening, for example, according to George Holtz. There's also the challenge of needing two vehicles when traveling anywhere. Even though the family has an eight-passenger van, it's not enough when they have visitors.

For the most part, the benefits outweigh the drawbacks, George and Susan agreed.

"I think they will all learn about children from different areas," said Susan. "They'll develop long-lasting friendships."

Ilaissa agreed, saying the Holtzes' children were like brothers and sisters and Susan and George like a second mom and dad.

The Negron girls look forward to their visit each year and keep in touch during the winter, she added. Susan hopes they visit until they turn 18, she said.

Each year, the Fresh Air Fund sends about 5,000 New York City children to suburban and small town communities across 13 Northeastern states and Canada so children can have outdoor experiences during the summer.

In the Butler County area, participation has grown from seven volunteer host families to 30 in the past six years, according to Brenda McCall, chairwoman for the Fresh Air Fund in the Butler area.

The organization is always looking for more host families, though, because there are always more children in New York City willing to participate than host families available.

Once families decide to host a child, it's common for them to invite the same children back, she added.

"The nice part is if you find a child you click with, you can watch them grow up and keep in contact," McCall said.

It's also common for larger families to become involved with the program. Those families are usually good candidates for hosting.

"They're more flexible and don't have unrealistic expectations of the kids," she said.

Those interested in more information about the Fresh Air Fund can call McCall at 724-283-4656 or visit the Web site at freshair.org.