Keeping Butterflies Afloat: Adapting Roadside Maintenance to Protect Monarch Habitat, Increase Agricultural Productivity, and Save Money

It was a typical, sticky Florida day in June when two University of Florida researchers were cruising down the highway. While the driver was behind the wheel, reading the curves of the road and navigating the peaks and valleys of northern Florida, the passenger was intently observing the terrain and surrounding plant life. The pair zipped past a patch of sandy soil, then a turkey oak tree with its deeply lobed leaves, followed by a tall embankment. Both knew it was time to slow down. They were not near any conventional destinations, but evidence suggested they were close to their goal. Eyes peeled, the spotter scanned the vegetation for their ultimate prize: milkweed. The research team, led by principal investigator Dr. Jaret Daniels, was searching for milkweed because of its importance as a food source and habitat for monarch butterflies.

The team was working with FDOT to identify milkweed plants along roadways in North Central Florida. From Pasco and Orange counties in the south to Gadsden and Liberty counties in the north, these plants are key to supporting and preserving the monarch butterfly. While the annual migration of monarch butterflies is an incredible event to behold, these creatures and the other insects that share their habitat help maintain the health of farmland, wilderness, and other ecosystems. Florida, in particular, is situated along vital migration routes for monarch butterflies. Unfortunately, the iconic North American butterfly has been facing steady population decline for decades.

Migration routes for the monarch butterfly overlap with the project research area in North Central Florida. Source: Migration patterns gathered from

Enter FDOT, which has a history of managing its right-of-way in an environmentally friendly manner. Maintaining the right-of-way using methods that support pollinator species, insects like the monarch butterfly that carry pollen from one plant to another, supports many of FDOT’s goals. A March 2014 study also found that environmental management produces at least a half billion dollars in benefits to Floridians.

Identifying Milkweed and Formulating a Strategy

The first step in the project was to locate areas with a high density of milkweed. Given the size of the research area in North Central Florida, the research team started by using GIS data to identify priority habitats near FDOT roadways. Armed with this information, the team conducted driving surveys to verify locations and provide valuable on-the-ground data. As described, surveyors would start by looking for habitat markers from the highway, such as sandy soil, turkey oaks, and high embankments, before investigating an area further.

Key milkweed species identified by the project team included butterfly milkweed (left) and pinewoods milkweed (right). Source: Dr. Jaret Daniels

These field surveys led to a discovery. Dr. Daniels says, “Most of the milkweeds were on the back slope of the roadway. The advantage of that is FDOT can still mow a portion of the right-of-way including a safety strip directly adjacent to the roadside without impacting the milkweed.”

This was a critical finding, as the team needed to balance the ability to reduce mowing in areas with milkweed while maintaining a clear zone to enable disabled vehicles to safely pull off the road. Luckily, milkweeds were largely in areas that did not need to be mowed for safety and aesthetics. This discovery was what Ashley Hagan Binder, landscape architect in FDOT’s Office of Design, describes as the “aha” moment: “We can modify our practices so that we can reduce mowing in that back slope area, save the milkweed, and save the monarchs.”

Keeping Blades off the Back Slope

Next, these findings had to be translated to the Office of Maintenance to implement new practices. The research team converted the collected field information to GIS data and used this information to identify areas with substantial milkweed populations. The team developed mowing plans to reduce the frequency of mowing along these areas, if possible.

While Dr. Daniels’s team were experts in identifying these plants, it was difficult in many cases for mowing operators to spot milkweed and know to avoid it. To address this challenge, FDOT Districts deployed various approaches to implementing best mowing practices, with valuable lessons learned.

Jeff Norcini, a consultant to FDOT’s Office of Maintenance, has seen which measures can be effective in preventing these important plants from being inadvertently cut down. He says, “What’s really worked to keep the mowers off is putting ‘test site’ signs on each end and painting ‘test site’ right on the shoulder.” On-the-ground direction has been an effective practice that furthers the intention and goals of the project: to protect milkweed as a habitat for monarch butterflies, which in turn supports Florida’s agricultural and environmental needs.

Sting Like a Bee: Opportunities for More Effective Habitat Preservation

While the monarch butterfly project has unique considerations, FDOT has found that it shares similarities with other right-of-way management initiatives like the Wildflower Program, which was created by FDOT in 1963. This initiative has improved aesthetics along Florida’s highways by maintaining stands of wildflowers while also lowering maintenance costs. Over time, this program has promoted more diverse biological corridors, increasing habitat for pollinator species and drawing ecotourism. In many ways, lessons from the wildflower program may be applicable to the maintenance of monarch butterfly habitats.

John Heller in FDOT’s Office of Maintenance provided some insight to the wildflower program and where support from other stakeholders has been valuable. He says, “Getting involved with the local wildflower agencies has helped out a lot because those are the individuals that are out there every day.” Just as local stakeholders help in alerting the Office of Maintenance when wildflower preservation areas are mowed, coordination between FDOT and these stakeholders can help protect locations with high densities of milkweed.

FDOT is doing their part to continue the practices of providing signage and pavement markings near important milkweed areas. As the research shows, providing benefits to Floridians through protecting agricultural and environmental interests often starts with locating the milkweed.

Further Reading

BDV31-977-49 Survey of Key Monarch Habitat Areas along Roadways in Central and North Florida
Final Report | Summary