Monday, June 14, 2010

How to Determine the Sex of a Monarch Butterfly


As you know, questions about Monarch butterflies are always welcome here.  My first question comes from none other than my dear sweet mom.  She writes: "How can you tell males from females in Monarch butterflies?"

That's a good question.  It's really quite simple.  Male Monarchs have two black dots on their lower two wings.  (see photos below.)  Females do not have these dots.  The dots are in fact scent glands which releases a pheromone that attracts the females to them for the purpose of mating.


It is even possible to determine the sex of a Monarch butterfly while it is still in its chrysalis.  This is done by taking a close look at the top of the chrysalis.  You might need a magnifying glass for this.  As you look at the top of the chrysalis, you will notice three pairs of two dots right below the cremaster.  Look right below the most bottom set of dots.  If you see a verticle line, then it is a female Monarch that will emerge.  If there is no verticle line, then it will be a male.  (see photo below.)


(In the above photo, the verticle line indicates that this a female Monarch.)

Happy Monarching!
Caleb & Janae Warren

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