Between August and October, migrating monarch butterflies, classified two years ago as endangered by the International Union for Conservation of Nature (IUCN), travel up to 3,000 miles from the United States and Canada to overwintering grounds in the mountains of Mexico. It’s a taxing journey for an insect that weighs about half a gram, or less than a paper clip.

Their journey is fueled by flower nectar, so they need plenty of food sources to alight on. Butterfly weed, common and swamp milkweed, red clover, blazing stars, bee balm, native thistles, purple coneflowers, asters, goldenrods, New York ironweed, Joe-pye weed, and sweet pepperbush all provide abundant nourishment.

Climate change, however, has significantly impacted the migratory monarch butterfly and is a fast-growing threat. The IUCN has noted “drought limits the growth of milkweed and increases the frequency of catastrophic wildfires, temperature extremes trigger earlier migrations before milkweed is available, while severe weather has killed millions of butterflies.”

Monarchs are first seen in Rhode Island in June. Their numbers increase through late summer and into fall, when secondary generations begin their journey southward. The orange and black butterflies can be spotted in gardens and fields, especially those with plenty of native milkweeds and flowers.

University of Rhode Island professor Steven Alm and research associate Casey Johnson noted the monarch is one of hundreds of species of butterflies and moths that call Rhode Island home for at least some of the year. Some are more common than others, but the monarch is one species with documented drastic declines.

They said many of Rhode Island’s local insects, including moths and butterflies, would benefit from residents and businesses planting more native vegetation, removing invasive species, reducing pesticide use, and leaving the leaves for overwintering insects.

Alm and Johnson hope to help cultivate support and awareness to help monarch butterflies, similar to the support other threatened species such as the bald eagle have received. Alm, keeper of URI’s Insect Collection, is concerned about the insect loss he has witnessed over his career.

During the past three decades, the eastern migratory monarch butterfly population has decreased by more than 80%, according to the World Wildlife Fund.

Increasing plant and animal literacy is one way for gardeners and wildlife advocates to help improve the insect environment, one plant at a time, according to Johnson.

“Butterfly gardens help,” she said. “We need more.”

The URI duo said one of the best ways to help support monarchs is to increase milkweed, an important food source that helps protect the larvae and adults from predators. Monarch larvae consume toxic substances in milkweed as they feed on its foliage. The toxins are transferred into the adult butterflies, which helps to protect them from predators such as birds.

Johnson is scheduled to lead a free “URI Bee Lab Walk & Talk” Saturday, Aug. 3, from 10-11 a.m. at the Spruce Acres pollinator garden in Middletown, R.I. To register, click here.

To help backyard and front-step gardeners be good hosts for the monarch and other beneficial insects, Alm and Johnson answered some questions about this unique species.

Why is milkweed so important for the monarch butterfly’s journey? Milkweed gets its name from the sticky white liquid exuded from its leaves when damaged. It’s the only food plant for monarch larvae. Generations of monarchs rely on nourishment from milkweed and other plant species to migrate between New England and the Sierra Madre mountains of Mexico. After resting there from November through February, the same butterflies migrate back to lay eggs on milkweed in the southern states. Monarch butterflies typically live from 2-6 weeks, however, the last generation of the year can live up to 8 or 9 months.

What has harmed monarchs? Development, forest removal in the butterfly’s overwintering grounds in Mexico, agricultural intensification, fire, climate change, and pesticides that remove milkweed and floral nectar sources. Severe weather also poses a challenge.

How can home gardeners help? Plant a 4-foot-by-4-foot area of any of the plants listed above, but even a few plants in a window box or in pots on steps can help. Keep in mind that if you plant milkweed and other native plants, you want caterpillars and other native insects to eat them. Buy milkweed and other native plants from nurseries that don’t use pesticides, or buy (save) seeds, store them in your freezer or outside for the winter, and plant them in the spring. If your garden is tight for space and you don’t want to plant native milkweed that would spread, try butterfly milkweed or swamp milkweed. Avoid planting tropical milkweeds or other milkweeds not native to the area.

What should Rhode Islanders look for at the start of the butterfly migration this season? Look for caterpillars on milkweed leaves, but don’t disturb them; leave them there to develop into adults. Adult butterflies are seen in Rhode Island from August through October. Let the pods develop on the milkweed plants until they break open and float their seeds via the “parachutes” attached to each seed. This parachute material is six times more buoyant than cork and five times warmer than wool. Large quantities of milkweed were grown for use as stuffing in pillows and lifejackets during World War II. In fact, milkweed seeds will mature on the plant and are ready to harvest once the pods break open in September or October.

Note: Not all monarch populations make major migrations. Monarchs migrate short distances in Australia and New Zealand. There are also some populations — in Florida and the Caribbean, for instance — that don’t migrate. Those that don’t migrate far distances are classified as vulnerable.