"TIGHTS and lights." That's how Alison Becker Chase cheerfully describes Pilobolus Dance Theatre, the out-of-this-world modern dance company she helped spawn in 1971. Back then she was a dance teacher at Dartmouth College when four precocious young men, none dancers, signed up for her class. "They had never seen modern dance before," she recalls, "so they had no preset expectations. They were completely fresh."

The four -- Robby Barnett, Lee Harris, Moses Pendleton and Jonathan Wolken -- were game from the start. Chase knew she couldn't teach them how to dance in one semester, but she could teach them how to use what they had to be inventive. From that class -- which emphasized highly physical, off-the-cuff movement and weight-sharing through lifts, leans, balances and other means of support -- a modern dance tradition was born.

The name Pilobolus refers to a phototropic zygomycete -- a type of fungus, for you biology novices -- whose properties intrigued Wolken, who'd seen them in his father's biophysics lab. Though just a quarter-inch tall, the sun-loving powerhouse can toss its spores nearly eight feet.

Pilobolus the dance troupe had goals just as ambitious, and for more than 30 years, the troupe has remained remarkably fertile, creating a body of repertory based on its unique weight-sharing and partnering skills honed in a collaborative environment.

On Tuesday, Pilobolus returns to Wolf Trap's Filene Center with "BUGonia," a world premiere commissioned by the performing arts park. "BUGonia" brings the Pilobolans back to their spores, so to speak. Chase explains the word she coined to name her newest duet: "It's a biomorphic creature that definitely hearkens back to our early roots." Those roots include rubber-limbed flexibility, tensile strength to lift and carry partners every which way, and a sense of attachment to the earth as dancers give into the unforgiving tug of gravity.

But "BUGonia" also showcases Chase's current fascination with airborne suspension. The dancers hang from the rafters instead of hugging the floor. "After working for 34 years," she says, "the use of suspension just spoke to me and allowed me to create a different stage picture up in the air."

The Wolf Trap program includes three other works -- all contributed by Chase -- that employ suspension. "Monkey and the White Bone Demon" is a plot-centered work culled from a 16th-century Buddhist myth; "Ben's Admonition," meanwhile, is a riveting and succinct male duet with military overtures that draws its title from Benjamin Franklin's statement on signing the Declaration of Independence: "We must all hang together, or assuredly we shall all hang separately." Using Chinese circus silks, "Star-Cross'd," also performed airborne, is a gloss on the literary lovers Romeo and Juliet.

For Chase, suspending her dancers above the floor, whether by ropes, harnesses or lengths of silk fabric, is never merely a circus trick. "The suspended imagery," she points out, "is always in service to the storyline, and suspension gives the work a sense of magic."

PILOBOLUS DANCE THEATRE -- Tuesday at 8:30. Filene Center, Wolf Trap, 1551 Trap Rd., Vienna. 703-218-6500.

Pilobolus Dance Theatre is known for its flexibility.