2018-19 Monarch overwintering numbers released

Each winter, pollinator enthusiasts anxiously await monarch population numbers as eastern populations overwinter in the forests of Mexico.

We’re excited to share that the 2018-19 overwintering monarch population is the largest it has been in more than 10 years. Monarch butterflies are covering 6.05 hectares of forested area outside of Mexico City, the largest area since the 2006-07 winter season.

Graph about monarch butterfly populations

This is great news for the main monarch butterfly population amidst dwindling populations in the last 25 years. A lack of host milkweed plants for monarchs to lay their eggs on and for their caterpillars to eat, pesticide use, not enough native habitat for adult monarchs to feed on during their journeys north and south — so many factors come into play as to why monarch butterfly populations have dwindled almost 90 percent.

(Read “How Do Monarchs Find Their Way South?”)

Those factors have also affected monarch butterflies on the west coast, and news surrounding those monarchs is not as positive. This smaller population of monarchs migrate south to overwinter on the Baja Peninsula, and the Xerces Society has found that the west coast population has declined 99.4 percent since the 1980s. In the 1980s, western monarch populations were estimated at 4.5 million, but the 2018 monarch butterfly count only reported 28,429 butterflies. That means for every 160 monarch butterflies in the 1980s, there is only one today.

Spring migration for monarch butterflies has yet to begin. For the main continental population, it will take four-six generations of monarchs to reach their northern-most territories in Iowa, Minnesota and even into Canada before the last generation heads back south to overwinter again in Mexico.

(Find out more about the majestic monarch’s magnificent life cycle)

We can all help those generations.

  1. Plant natives! There are plenty of milkweed varieties, read about them here, that are beneficial and also beautiful in landscaping.
  2. Cut down on pesticide use. Neonictinoids are considered harmful to pollinators, and many other chemicals that have widespread usage are not only deadly to bugs people don’t want around but they are deadly to everything. That means chemicals that kill mosquitoes also kill pollinating bees, butterflies, moths, beetles, ants and other beneficial insects.
  3. Get involved. Monarch Watch is asking for citizen scientists to keep track of monarch butterfly numbers throughout the country to help more accurately identify populations. You can sign up to count butterflies in your own community. Find out more about that here.
  4. Advocate. Make sure to talk to your friends, your neighbors, your family about the importance of pollinators and taking small steps in our own yards that will help bring back our populations.

Learn more about pollinators inside Pollinator Paradise at the Dickinson County Nature Center!



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