Monarch Butterflies

Threats to Monarch Butterflies

Monarch butterflies are one of America’s most iconic insects, and the most recognizable butterfly in the world. However, these charismatic creatures are in danger. Since the 1990s, the monarch population has declined by 90 percent . In recent years, this decline has worsened, with the 2023-2024 season seeing monarch numbers at a mere 5% of their numbers 30 years ago .

The main contributing factors to this rapid decline are the increases in habitat loss, pesticide use, and climate change.

Monarchs are special in that the caterpillars feed exclusively on a plant known as milkweed. For monarchs to reproduce, milkweed must be present for adults to lay their eggs. Urban sprawl and farming have caused the destruction of many areas where milkweed was historically present. Climate change has caused increases in extreme weather events such droughts in the summer and changes in flowering patterns that monarchs rely on to make the annual 2,000+ mile migration from Mexico to Canada.

However, the biggest threat to monarchs is the overuse of pesticides and herbicides. Excessive use of these chemicals kills monarchs and their caterpillars and have been the main factor in the decline of the monarch population in recent years. Insecticides used in agriculture, especially a type known as neonicotinoids, may have contributed to dramatically reduced monarch populations. Additionally, herbicides commonly used in yards and landscaped areas can have hazardous effects on monarchs and other beneficial insects, while also killing the milkweed plants the butterflies need to reproduce.

Habitat Range

Monarchs are one of few insects that migrate. Their range stretches from central Mexico to southern Canada. The monarchs we see in Glenview are part of the eastern population which is separated from the western population by the Rocky Mountains. For the eastern population, adult monarchs breed in southern Canada, the Great Lakes region, and the Northeast and Southeast states in the summer. In the winter they fly south to the oyamel fir forests of the Sierra Madre Mountains in Mexico.

The migration relies on successive generations every year to be completed. While one generation makes the journey back south for the winter and starts the journey north again in the spring, there are multiple generations born in the summer that never make this trip, but they are vital in continuing the species.

Importance of Monarch Habitat in Glenview

While monarchs can fly as far north as Canada, some of them stop farther south. Since Glenview is in the migration path, some monarchs stop here to reproduce. Because of this, the Village of Glenview has made a Monarch Conservation Plan . The plan further explains the threats to monarchs, importance of Glenview as monarch habitat, and what the Village is doing to protect monarchs on Village property.

The Village of Glenview has completed numerous projects designed to improve monarch habitat. Pollinator gardens have been created at central locations including Village Hall and the downtown train station, as well as on landscaped medians along Patriot Boulevard and Chestnut Avenue. Milkweed and other native plants have been seeded and maintained at open spaces such as Techny Basin, Gallery Park, Air Station Prairie, and the downtown West Fork Riverwalk. These areas are part of a regional network of habitats that monarchs rely on during migration and throughout the summer. Recent restoration projects along the West Fork of the North Branch of the Chicago River, such as the Pine Street and Longvalley Road riverbank restoration projects have also prioritized the planting of milkweed. The Village has also engaged in public outreach through boy scout projects and farmers market Green Tables.

While the Village is continually working to increase and improve monarch habitat on Village owned land, you can also help to protect monarchs, right in your backyard!

What Can You Do?

If you are a property owner, you can increase monarch habitat. Make a butterfly garden!

While monarch caterpillars rely on milkweed to eat, adult monarch butterflies need nectar from many different flowers. Therefore, it is important to provide many types of nectar plants other than just milkweed to fully support monarchs as well as other pollinators like hummingbirds, bees and other butterflies. While being functional, these gardens can also be very beautiful and take many shapes and forms depending on which flowers you decide to use. The Illinois Department of Natural Resources has a great guide on what to plant , as does the Xerces Society .

Consider certifying your property as a wildlife and native plant habitat through Conservation @ Home or the National Wildlife Federation , or as a Monarch Waystation ! This certification shows your community that you are dedicated to providing space for the other critters with which we share our neighborhoods.