SLIPPERY ROCK TWP — The Jennings Environmental Center, 2951 Prospect Road, will hold the following events:

• A short hike a 10 a.m. Saturday will investigate the natural history of butterflies.

• A guided 90-minute walk discussing the plants, animals, history and geology of the prairie will be offered at 2 p.m. Sunday.

For information, call the center at 724-794-6011.

The following family reunions are planned:• JACKSON TWP — The Hamilton and Sarah McCartney 99th annual reunion will be Sunday at the Lambert residence/pavilion, 386 Fanker Road. Meals are at 1 and 5 p.m. Please take a covered dish, table settings and swimwear if using the pool. Beverages will be provided. For information, call 724-452-8970.• BUTLER TWP — The Wise Daniel and Polly Powell reunion will be held Sunday at Bob and Alene Sankey's home, 138 Green Manor Drive. Take a tureen and white elephant item; beverages and table service will be provided. The meal is at 4:30 p.m.• SLIPPERY ROCK TWP — The Peter Oesterling reunion will start at 2 p.m. Aug. 8 at Slippery Rock Park, 116 Lone Pine Way. Take a side dish, chairs, and table service. Water paraphernalia will be needed for fun in the creek. For information, call 724-285-8162 or 724-355-1222.

BUTLER TWP — St. Mary's Church will hold its annual picnic from 11 a.m. to 5 p.m. Sunday at the church, 821 Herman Road.Ham and grilled chicken dinners will be served. There will also be food, musical entertainment, games, raffles and a country market.Extra parking is available at the Herman Firehall; there is a free shuttle service.

The YWCA preschool Montessori educational program for 3- to 5-year-olds is now accepting registrations for the 2009-10 school year.The preschool features an option of traditional Montessori four days a week or modified Montessori two or three days a week. Classes will be held Monday, Tuesday, Thursday and Friday from 9 a.m. to noon or 12:45 to 3:45 p.m.For information, call 724-287-5709.

JACKSON TWP — The Zelienople Library will hold a series of programs for adults from 9:30 to 10:30 a.m. on Saturday mornings.Breakfast will be provided and participants can attend as many or as few programs as they wish.Programs include:• Aug. 8, Allegheny National Forest by Joe Hardisky of the Friends of the Allegheny Wilderness• Aug. 15, 'Are you getting what you pay for?' with Mary Bach, AARP• Aug. 22, 'Should I keep this?" antiques appraisal with Linda McCrady• Aug. 29, emergency preparedness with Al Wilson, homeland security planner with Butler County Emergency Services• Sept. 5, "Food and Fun with Jolene" nutrition, food safety and cookingIf interested, call the library at 724-452-9330 to make sure the schedule has not changed.