tropicalbats.com
  • Home
  • Bats
  • Places of note
    • Suriname
    • Costa Rica
    • Norway
    • The UK >
      • London
    • The United States
  • critter essays
  • Birds
    • Suriname birds
  • tropicalbats blog
  • Coins: Errors, Varieties and Photography

Bombay Hook - Monarch Butterfly laying eggs on milkweed plant

9/22/2017

1 Comment

 
This is a photos of a Monarch butterfly, laying eggs on a milkweed plant.  Happens all the time, but there is more to this relationship than simply a butterfly finding a good place for the young to grow up.

​There is way more to this story than I can get into here, but two things are worth knowing.  First, the milkweed plant contains toxic chemicals, and second, that even though monarch numbers have been way down in modern years just planting more milkweed isn't a perfect solution.

​
Picture
Monarch butterfly laying eggs on a milkweed plant at Bombay Hook
So, the milkweed plant is toxic, specifically containing cardenolides that are not fun to eat. But the larval butterflies, you know, caterpillars, eat up milkweed like crazy.  In fact, it is pretty much all they eat, from at least of the 27 species of milkweed in North America.

​And as for the toxins, well, they sequester them.  This allows these cardenolides to stay in their body through metamorphosis and arrive in the adult butterflies, having no seeming effect on the animals.  But you still won't like it if you eat these toxins, so chowing down on a monarch will likely induce vomiting or similar stomach distress.  Animals that eat a monarch butterfly learn that this is not good food, and avoid them in the future.  Nifty little strategy they've got going there.  Side note:  the very tasty Viceroy butterfly mimics a monarch's colors to not get eaten since it looks like the awful-tasting one.

​So with the numbers of monarchs decreasing (mainly due to habitat loss and pesticide spraying), a grand plan was hatched to have gardeners plant more milkweed.  Seems very reasonable, since milkweed makes for a nice garden plant and will attract the pretty butterflies.  Well, all is not perfect here.  Seems like most all of the available milkweed plants to gardeners in the US are tropical milkweeds, which have a problem.  

​Milkweed can carry a parasite that is hard on the butterflies, and they can pick it up during the caterpillar stage while eating the leaves.  They then pass it on to the adults, which weakens them severely and can prevent them from having the strength to migrate (many go all the way to Mexico!).  This whole problem has historically been kept in check by all the milkweeds dying off each winter along with most infected adults.  Each year the unaffected adult butterflies return to relatively unaffected milkweed.

​But tropical milkweed is different.  In parts of the US, like southern Texas, it does not die out but survives the winter.  This provides both for continuing the infection and also a side problem whereby some butterflies now do not continue their migration but just stop there as the milkweed remains present (and continues to infect them).

​So, monarchs have had it tough lately, even with a large effort to help them out.  And this is just a small snippet of the whole story, but certainly an interesting story to learn.


1 Comment
Linda
10/31/2017 12:57:59 pm

So, when the grass cutters at Greenfield cut down all the milkweed plants, was that a good thing? Here I am complaining that they chopped them down!

Reply



Leave a Reply.


    Author

    Keith Christenson - Wildlife Biologist

    Categories

    All
    Akershus Fortress
    Angry Baby
    Aurlandsfjord
    Bat Coins
    Bats
    Bird
    Birds
    Blast From The Past
    Borneo
    Butterfly
    Camouflage
    Caterpillar
    Caving
    Comets
    Costa Rica
    Crazy Video Links
    Crazy Video Links
    Cricket
    Cuba
    Denmark
    Dominican Republic
    Festivals
    Finse
    Fish
    Flower
    Flowers
    Folk Museum
    Freia Chocolates
    Frog
    Frogner Park
    Geese
    Goose
    Grønland
    Harvestman
    Hawaii
    Hedgehog
    Holiday Cards
    Huk
    Ice
    Insect
    Ireland
    Isopods
    Jamaica
    Kolsastoppen
    London
    Mammals
    Mexico
    Mourning Cloak
    Mushrooms
    Naeroyfjorden
    National Day
    Norway
    Ohio
    Oslo
    Oslo Opera House
    Oslo Summer Park
    Panama
    Patterns
    Pennsylvania
    People
    Pond
    Puerto Rico
    Roof Animals
    Scotland
    Sognsvann
    Spiders
    Spring
    Suriname
    United States
    United States
    Venezuela
    Virginia
    Washington Dc Area
    Washington Dc Area
    West Virginia
    Woodpecker
    World's End
    Zambia

    Author

    Keith Christenson
    Wildlife Biologist


    RSS Feed

    Archives

    April 2019
    March 2019
    February 2019
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    December 2013
    November 2013
    October 2013
    September 2013
    August 2013
    July 2013
    June 2013
    May 2013
    April 2013
    March 2013
    February 2013
    January 2013
    December 2012
    November 2012
    October 2012
    September 2012
    August 2012
    July 2012
    May 2012
    April 2012
    March 2012
    December 2011
    January 2011
    November 2010
    October 2010
    June 2010

Proudly powered by Weebly
Photo used under Creative Commons from Evil_Prince