2019-20 Monarch overwintering numbers released

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

This winter, we have some less than ideal news as monarch overwintering numbers dropped by more than 50 percent from the 2018-19 season --- going from 6.05 hectares of overwintering area covered last year to 2.83 hectares in the 2019-20 winter season.

Graphic about monarch populations

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 in the past 30 years. Chip Taylor, director of the University of Kansas Monarch Watch program predicted that 2019-20 populations would be down, and he was right. (Read his blog here)

To summarize, he said that monarchs moved too far north too quickly last spring, encountering cool temperatures and inhibiting growth of the first population of caterpillars. That inhibited growth continued throughout the rest of the monarch generations going north, creating a late migration south as well.

In addition, monarch populations seemed to be low in Iowa and western portions of the upper Midwest throughout the season. The temperatures in the summer of 2019 were average, but temperatures slightly above average --- such as what happened in 2018 --- help monarch populations to really boom.

A Texas drought also seems to have impacted monarch populations during migration, because nectar was in short supply as monarch butterflies flew south to Mexico for the winter.

(Read "How Do Monarchs Find Their Way South?")

Not all monarch butterflies overwinter in Mexico. There is a population of monarch butterflies on the west coast, and news surrounding those monarchs is not positive either. 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 begun for 2020. 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!



Why do monarchs overwinter in Mexico?

Most people familiar with monarch butterflies know that they migrate to central Mexico to overwinter. You can read in-depth how monarchs find their way here, but in general, they use their circadian rhythm to orient themselves with the direction of the sun and also use the earth’s magnetic field to fly toward the equator. However, Read More »

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10 monarch butterfly questions answered

We get a lot of questions at the Dickinson County Nature Center, and a lot of them have to do with butterflies and bees. Let’s take a look at some of our most commonly asked questions about monarch butterflies. How long do monarch butterflies live? A monarch is in the egg stage for three-five days, Read More »

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Egg carton butterfly

I saw a funny meme about looking for recipes online and having to click on a post that instead of giving you the list of ingredients instead goes through “When I was senior in college, I walked down the long and misty concrete pathway and across a spring green lawn filled with bright dandelions….” So Read More »

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4 keys to telling apart monarch and swallowtail caterpillars

We stress that it is important to plant milkweed because it is the only plant that monarch butterflies lay their eggs on and that their caterpillars eat. However, some people have come to us confused that monarch caterpillars are eating the dill in their yard. Taking a closer look though, it’s not monarch caterpillars eating Read More »

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Make a coffee filter butterfly

It’s not any surprise that we love butterflies at the Dickinson County Nature Center. We also love butterfly crafts! This coffee filter butterfly is one that we made at the 2018 Bee & Butterfly Festival. It’s simple, but kids really love the colorful creations they can make. Plus, you can glue them to a magnet Read More »

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The majestic monarch’s magnificent life cycle

A few more weeks and the monarch butterflies that are overwintering in Mexico will start making their way north. Once coming out of hibernation, a female monarch will find a male with which to reproduce. Around the Texas/Mexico border, the female monarch will find milkweed plants on which to lay her eggs. She can lay Read More »

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How do monarch butterflies find their way south?

Those wonderful orange-and-black butterflies that we love so much. They fly overhead this time of year, and we know they are headed to their overwintering sites outside of Mexico City. But how do they get there? Plenty of studies have been done throughout the years to try to figure out how a brain the size Read More »

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Create an origami butterfly!

I thought I would try my hand at a paper butterfly today and give you some directions to try it out yourself! Step 1: Create a waterbomb base. Fold your square of paper in half, then in half the other direction. Unfold the paper and fold it into a large triangle. Unfold the paper. Flip Read More »

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  1. AmyT on May 2, 2019 at 9:56 am

    Hi, thank you for this article. I am confused that this was written in March 2018 but it talks about winter 2018/19 population—should it instead say winter 2017/18?

    • kiley on May 2, 2019 at 10:08 am

      The original post was written in 2018 and then was re-written and updated with the 2018-19 numbers in March 2019, so it is the accurate 2018-19 numbers 🙂 Sorry for the confusion!