LITCHFIELD -- Delicate, ethereal and beloved by gardeners who plant flowers to attract and feed them, butterflies are becoming scarce in Connecticut.

About one-fifth of the 117 butterfly species native to the state including the silvery checkerspot, northern metalmark and frosted elfin are now listed as rare and endangered by the states Department of Environmental Protection, a decline that has been most precipitous in the past three years.

The causes haven't been positively identified, nor have exact numbers been tabulated, but entomologists believe habitat destruction and two years of cold and rainy growing seasons have taken a toll.

Along with the disappearance of other species, including salamanders, bats and some types of turtles, the disappearing butterflies are seen as a signal that something is out of whack.

"It's a result of habitat destruction and degradation," University of Connecticut entomologist Jane O'Donnell said. "They aren't as numerous as they once were."

Some of the reasons are more easily defined than others, O'Donnell said. What is left of an ecosystem fragmented by development has suffered climate changes.

The widespread use of chemical herbicides and pesticides is also thought to contribute.

Last year, University of Connecticut science professor David L. Wagner noted a two-year precipitous decline in the number of northern metalmark butterflies in counts conducted in Falls Village.

The metalwork lays its eggs on Senecio obovatus, a plant that prefers the region's lime-stone rich soil. A garden established in 1998 at the White Memorial Foundation in Litchfield to attract butterflies has been re-classified as a pollinator project.

A variety of native plants attract birds, insects, honeybees, flies, butterflies and moths. This year, all of them are having a hard time and some populations are absent, said Polly Brooks, co-chairman of the conservation committee of the Litchfield Garden Club.

In Easton, Christine Cook designs ecological landscapes and serves as conservation chairwoman for the Connecticut Butterfly Association, which seeks to educate the public about butterflies.

"Yes, there is a decline, but it's hard to tell what the cause is," Cook said. "People, especially seniors, have asked what happened to them all. Certainly one of the reasons could be a loss of habitat, but it could also be part of a natural cycle."

A decline in the population of monarch butterflies, which migrate to wintering grounds, has been attributed at least in part to an increase in logging in the areas where they spend the winter in Mexico.

Cook designs butterfly habitats for schools and parks across the state. Her latest project is the restoration of a butterfly garden at Connecticut's Beardsley Zoo in Bridgeport, where the goal is to offer many food sources for butterflies in the caterpillar stage that eat leaves, and nectar for them to sip after they take to the air.

"The hope is that children will get excited about butterflies, and take that interest home," Cook said.

In Warren, Peary Stafford is a member of the board of trustees of the Steep Rock Association and helped establish a butterfly garden at the 450-acre Macricostas Preserve in Washington.

"There are many fewer but-terflies and some species are totally absent," said Stafford, who has also noticed fewer dragonflies. "In a visit to New Hampshire a month ago, I went looking for six species of butterflies and found none. I don't know what to attribute it to."

Stafford doesn't think chemicals have anything to do with the decline.

"Chemicals have been around a while, but this weather is unprecedented in at least a generation. We are all hoping it's just the odd weather and that they will return. They have an incredible ability to recover."