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More to monarch decline than just milkweed

More to it than just the Milkweed

BLOOMINGTON, Ill. – Most Illinois gardeners believe that the cause of declining monarch butterfly populations is due to the lack of milkweed in the summer breeding areas of our state. However, research done by the Illinois Natural History Survey, plant ecologists, Greg Spyreas and David Zaya is proving there may be more to the story than just the lack of milkweed.

Illinois is home to 19 native milkweeds. In the last 20 years milkweed has decreased by 95% in agriculture fields, David Zaya says, "the natural areas are buffering the loss, maintaining about 50% of milkweed enabling the monarchs to build up their normal population numbers throughout the summer." Scientists now believe the decline in the population may also be due to the lack of floral resources on their long, exhaustive journey back to Mexico and are urging gardeners to create a monarch corridor or "floral highway."

To create these floral highways, planting more fall blooming perennials need to be in gardens. Scientists do not want gardeners to stop planting milkweed as a larvae food source for caterpillars. In addition to being a larval food source for monarchs, milkweed is also a highly sought after nectar resource for adults.

If you add new plants to your garden or start to build a new landscape, Greg Spyreas says, "fall blooming perennials like liatris, joe pye weed, black eye Susan, bee balm, aster, coneflower, and helianthus would be excellent additions to your gardens for the late feeding of monarch butterflies."

Liatris pycnostachya (Prairie blazingstar) - Blooms mid to late summer on large erect pink to purple spikes. Full sun, not drought tolerant when young.

Eutrochium purpureum (Joe pye weed) - Blooms mid-summer to early fall; pink to purplish pink panicle of compound flowers. Light shade to partial sun.

Rudbeckia hirta (Black-eyed susan) - Blooms early to mid-summer; Dark-brown central cone with yellow petal-like rays. Full sun, easy to grow but short-lived biennial.

Monarda spp. (Bee balm) - Blooms in summer for up to two months; a three to four-inch ring of tubular flowers ranging from pink to red. Partial sun and moist conditions.

Symphyotrichum shortii (Smooth blue aster) - Blooms late summer to fall and lasts one to two months; yellow centers with blue-violet petal-like rays. Partial to full sun, pinch to keep compact.

Echinacea purpurea (Purple coneflower) - Blooms mid- to late summer; Central brown cone with purple to pink petal-like rays flowers. Full to partial sun; prefers well-drained soil; drought tolerant once established.

Helianthus mollis (Downy sunflower) - Blooms late summer to early fall; large bright yellow composite flower. Full sun; tolerates drought; forms dense colonies.

Additional gardening practices like adding a water source, planting multiples of one kind of plant in groups, avoiding pesticide use, allowing herbs to flower and planting annuals like Mexican sunflower, zinnias and cosmos can be of great benefit to the traveling monarchs.

University of Illinois Extension Horticulture Educator, Kelly Allsup, says by helping the monarchs, you will also help a host of other pollinators and wildlife by creating habitat they need to survive. "Floral highway" your yard.

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Written by University of Illinois Extension Horticulture Educator for Livingston, McLean & Woodford Counties Kelly Allsup.

Photos Provided Include:

Monarch on Hand (University of Illinois Extension McLean County)

Adult feeding on lilac (Deanna Frautschi, Master Naturalists and avid photographer)

Milkweed and larvae (Kelly Allsup, University of Illinois Extension)

Sources Include:

  1. Milkweed losses may not fully explain monarch decline
  1. Design your own pollinator garden with Pollinator Pockets
  2. Illinois Wildflowers