You’ve been waiting for that special day to arrive. When it does, however, nothing is ready, and what you hoped to find is no longer there. This is what it’s like for monarch butterflies when they find mowed fields instead of their needed habitat. There is no milkweed on which to lay their eggs, no nectar to drink from blooming flowers. We at the U.S. Fish and Wildlife Service recognize how vital farmers are to growing habitat on their working lands to nourish monarch butterflies.
Milkweed growing in a non-crop area of a farm. Photo courtesy of Wayne Fredericks/American Soybean Association
If you are a farmer or landowner, among the most simple and effective measures you can take to conserve monarch butterfly populations is to follow best practices for mowing. When establishing monarch habitat, or conducting management activities to keep the site healthy for your operations, mowing can be an important tool.
When to mow
Once monarch habitat is well-established, we suggest mowing or prescribed burning every three to five years to maintain high-quality habitat. When mowing is necessary, avoid peak monarch activity to minimize direct impacts to the monarch larvae growing on the milkweed plants. Visually inspect for any monarch activity, like eggs, caterpillars, or frass (caterpillar droppings) and take appropriate measures to protect ones you observe. However, there are more factors to consider when incorporating best practices for mowing your land.
How to mow
Milkweed is the only plant on which monarch caterpillars feed. If mowing is required, limiting it to only targeted areas (for example, weedy areas) and not mowing an entire habitat will ensure that some areas are left for caterpillars to feed and grow.
Avoid mowing when monarchs are present. Understanding the breeding and migration cycles of monarchs can help give a timeframe to mow. Use our monarch migration map to inform your management window. Typically, mowing windows occur regionally throughout the United States: November to March for the south, October to April for middle states, and September to May for the north.
Use a minimum cutting height of 8 to 12 inches to minimize impact on native plants and to remove seed production of weedy plants.
Protect other wildlife, like deer and nesting birds, by mowing at reduced speeds and using a flushing bar to allow wildlife to escape while mowing.
Finally, step back and consider that a mowed area is a desert in the eyes of a monarch. Consider whether or not these areas are worth the time and expense it takes to mow them as they may be the only areas left to support vibrant and necessary monarch habitat.
Plant additional habitat
Find new places on your farm for monarchs, other pollinators and wildlife to thrive by converting idle areas to prairie or pollinator habitat. Good options for areas on a farm to leave in a more natural setting include garden edges, next to adjacent buildings, unproductive portions of fields, and alongside alleyways, roadsides or in ditches.
By implementing these simple best practices, you can play a big role in conserving pollinator habitat and supporting monarch populations.