Monarchs & Mowing

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The Kerr County Road and Bridge Department, which is responsible for mowing along roads in county rights of way, has responded to citizen pleas aimed at monarch butterfly conservation.

Public safety is the number one priority of the department when it comes to mowing, but after receiving multiple requests to delay mowing in areas where milkweed is prevalent, the department turned to a Texas Wildlife Department and Texas Nature Trackers biologist for input.

Milkweed is a favorite for the monarch butterfly (Danaus plexippus), which uses it as a food source during both fall and spring migrations, as well as a place to lay and hatch eggs in the spring.

After consulting the expert several years ago, Kerr County Road and Bridge altered its mowing schedule in an attempt to minimize any adverse impact on the monarch butterfly migration patterns. Now, the department generally mows in June and October -- two months that fall outside the normal migration time frame for the popular orange-and-black butterflies.

That said, exactly when the county starts its two-month mowing season process is dependent on the weather. If the county has received a lot of rainfall, rapid weed growth may dictate that, in the interest of public safety, the department cannot postpone the first mowing until June.

The following information was put together as an informational packet for citizens interested in the monarch’s life cycle in relation to the county’s mowing practices.

MONARCHS, MILKWEED, AND MOWING

Issue: Kerr County residents are concerned with local mowing schedules and the protection of the milkweed plant in an effort to increase the monarch butterfly population.

Facts about monarch butterflies:

Migration (Fall)

  • Monarchs migrate south in the fall (September/October)\

  • During the fall migration no eggs are laid.

  • Milkweed is not the only food source (other perennials, chives, etc.)

  • These butterflies are the 4th generation (meaning three other generations have already been laid, hatched, and reproduced across the United States.)

 Migration (Spring)

  • Monarchs migrate north in the spring (March-August)

  • During the spring migration eggs are laid.

  • Milkweed is the only source of food for newly hatched larvae (caterpillars).

  • First-generation eggs are laid in March/April.

  • First-generation butterflies are grown, flying north and reproducing approximately one month later in May/June.

Migration, in general

  • Monarchs were sighted in March 2019 for the northern migration in San Antonio and Austin, but were not seen again until January 2019 for the southern migration.

  • Kerrville has a recognized monarch way station at Riverside Nature Center, 150 Francisco Lemos Street in Kerrville.

  • Additional sites where plants have been planted for butterfly conservation in Kerr County are: the Kerr County Courthouse, the AgriLife Extension garden and Kerrville-Schreiner Park, among others.

Source sites:

https://journeynorth.org/sightings/

https://monarchbutterflygarden.net/5-spring-plants-save-monarch-butterflies/

https://www.cityofirving.org/2737/Monarch-Butterfly-Life-Cycle

https://tpwd.texas.gov/huntwild/wild/wildlife_diversity/texas_nature_trackers/monarch/

Facts about Milkweed:

  • Milkweed grows in ditches, pastures and anywhere with full sun and open space.

  • Milkweed goes to seed in the fall.

  • Seeds germinate in the spring.

  • Roots are established all summer, resulting in modest plants difficult to identify.

  • Young milkweeds have fewer predators than older milkweed plants and are preferred for laying eggs.

Source sites:

https://seed-balls.com/life-cycle-of-milkweed

https://npsot.org/wp/story/2011/1702/

https://thedaytripper.com/the-monarch-butterfly-migration-in-texas/

Facts about mowing:

  • Required for public safety along roadways.

  • Mowing twice a year is recommended as a best practice for milkweed conservation.

  • Recommended times to mow the Southern Plains, which includes all of Texas, is midsummer (June/July) and early fall (September/October).

  • Appropriately timed mowing can help promote milkweed growth.

Source sites:

https://monarchjointventure.org/images/uploads/documents/MowingForMonarchs.pdf

https://www.futurity.org/monarch-butterflies-milkweed-conservation-2005712/

https://greatlakesecho.org/2019/05/17/mowing-milkweed-means-more-monarchs/

Kerr County Road and Bridge mowing practices:

  • Kerr County Road and Bridge mows the rights of way on county-maintained roads twice per year (June/October).

  • Mowing requests from the public are completed.

  • Public safety is priority over conservation.

  • Our mowing crew consists of three people and usually only two mowers operate at one time.

  • There is usually only one mower operating in a work area at a time meaning one mower may be in Comfort while the other is in Hunt.

  • It takes two months minimum to complete one season of mowing.