IF YOU'RE IN Mayfair in May, you might want to look for a new crop of monarch butterflies.

They will be part of the Mayfair Monarch Project, an effort to increase the number of monarch butterflies in North America, and spruce up the corridor between Mayfair and Holmesburg.

The project is the brainchild of Steve Kanya, who for 24 years has operated a not-so-little shop of critters called the Insectarium in Holmesburg.

In a few weeks, Kanya plans to unveil a new Butterfly Rainforest Pavilion inside the 8,000-square-foot warehouse behind his existing business and museum.

"I just love butterflies, and the monarch, you just don't see them around anymore," Kanya, 62, said.

"They're down in population about 90 percent because there's no more milkweed plants. And it's the only plant that monarchs use to lay their eggs."

The monarch is not on the endangered species list. But a petition has been filed with the Department of the Interior to add it, said John Cambridge, 26, a Ph.D. candidate at Rutgers University in New Brunswick, N.J., and the Insectarium's director of operations.

The reason for the decline is that the milkweed plant has been decimated by herbicides and the growth of corporate farming, Cambridge said.

For more than a year, thousands of milkweed and other plants that will provide nectar, or food, for the butterflies have been growing in back rooms and, recently, outside the building that houses the insect museum.

In the museum, which was once featured on David Letterman's show, 300,000 insects, reptiles, and amphibians are on display: scorpions, spiders and beetles, lizards, iguanas, and frogs from all over the world.

The Insectarium is part of the same building where Kanya, a retired police officer, still operates his 40-year-old pest-control business, Steve's Bug Off, on Frankford Avenue near Welsh Road.

Yes, Kanya went from killing and eliminating pests to creating a museum for living insects and reptiles in 1992. But that's another story.

But the new butterfly pavilion isn't just about Kanya.

It's a story about several neighborhoods joining together to improve Frankford Avenue, from Mayfair to Holmesburg.

About a year ago, Kanya met with leaders of the Mayfair Business Association and Mayfair Civic Association, and nearly every civic group and business owner supported the idea.

"We thought the monarch butterfly theme was a great way to beautify and unify the Frankford Avenue corridor," said Mia Hylan, a board member of the Mayfair Community Development Corp.

"What [Kanya's] done with the Insectarium, he's going to translate that to the butterfly pavilion, and it's going to be an asset to the city and to the Northeast," Hylan said.

Mike "Scoats" Scotese, president of the Mayfair Business Association and owner of the Grey Lodge Pub, agreed.

He said that last fall, civic groups began encouraging residents in Tacony, Wissinoming, Mayfair, and Holmesburg to grow milkweed in their yards, "so wherever the butterflies flitter to, they will find milkweed to make more monarchs."

The project also depends on support from Lincoln High School's horticultural program.

Students have been growing milkweed at school, and will also plant milkweed and other butterfly bushes in large planters on the avenue, from Harbison to about Sheffield.

Different groups of volunteers help out. On Thursday, volunteers from People Acting to Help (PATH), a program for developmentally challenged adults, came to seed plants. "I feel good about helping my community and the environment by bringing the butterflies back," Josh Milman said.

The goal is to have the pavilion ready for the Mayfair May Fair annual street festival on May 21.

Kanya said he was ordering 2,000 monarch butterflies and 6,500 other butterflies for the pavilion. But he'll only release a couple of dozen butterflies at the festival.

215-854-5987 @ValerieRussDN