The Dallas County Road Department reminds Iowans to protect roadside habitat for pollinators, nesting game birds and song birds this spring and early summer.
According to Iowa Code 314.17, mowing roadside ditches is restricted until July 15, to protect young pheasants and other ground-nesting birds until they are ready to fledge. The law, which applies to county secondary roads as well as state primary and interstate highways, also helps protect habitat for pollinators and other beneficial insects. Crop-pest predators such as lacewings and hover flies are two groups of beneficial insects whose larvae feed on soybean aphids, but the adults require nectar and pollen to continue their life-cycle.
Exceptions for visibility and weed control are built into the law, but non-essential mowing – including cutting for hay – is prohibited.
Iowa Code 314.17 states: Mowing roadside vegetation on the rights-of-way or medians on any primary highway, interstate highway, or secondary road prior to July 15 is prohibited, except as follows:Within 200 yards of an inhabited dwellingOn right-of-way within one mile of the corporate limits of a cityTo promote native species of vegetation or other long-lived and adaptable vegetationTo establish control of damaging insect populations, noxious weeds and invasive plant speciesFor visibility and safety reasonsWithin rest areas, weigh stations and wayside parksWithin 50 feet of a drainage tile or tile intakeFor access to mailbox or for other accessibility purposesOn right-of-way adjacent agricultural demonstration or research plots
Iowa’s roadsides provide a valuable refuge for wildlife and beneficial insects. The mowing law mainly focuses on nesting birds and serves as a reminder to only mow shoulders during the critical nesting season.
Still, indiscriminate summer mowing after July 15 can be detrimental to many pollinators, significantly weaken native plants and create openings for noxious weed invasions, such as Canada thistle, which sets seed in July and August. Thus, when managing brush and weeds it is recommended to use a spot-mowing approach and leave as much perennial grass and wildflowers as possible.
For more information, see a brochure called Iowa’s Mowing Law for Roadsides, available at: https://tallgrassprairiecenter.org/irvm-brochures.