Sandy Oliviera has raised monarch butterflies in her East Providence backyard for 25 years. In 1998, she helped 125 monarch caterpillars transform into butterflies, and then released them to the wind. “I began to feel like a butterfly factory that year,” Oliviera said. Each time her husband or daughter collected milkweed to feed their captive caterpillars, they returned with more eggs or caterpillars to raise. Some days, Oliviera released a dozen newly emerged butterflies, to the pleasure of her 8-year-old grandson who let them rest on his head before they flew away. This summer, for the first time, Oliviera hasn’t found a single monarch egg or caterpillar, and hasn’t seen any monarch butterflies.