Sex and the Single Butterfly

The only kind of butterfly with which I am the least bit knowledgeable is the Monarch.  In fact it is the only butterfly that I might be able to identify.  It also appears to be the star of the soon to begin Butterfly Festival here in Mission, TX.   So what is so special about this insect?  They each weigh less than 1 gram (0.035 oz.) and they fly from Canada to Mexico, up to 3,000 miles in 2 to 4 weeks.

Before we begin to unravel the mysteries of the butterfly migration it seems appropriate that everyone should be familiar with the life cycle of the Monarch butterfly.  This will be the subject of today’s lesson.  Now, listen carefully, class.

First of all, the Monarch’s life cycle is composed of 4 separate stages.  These are the egg, the larvae (caterpillar), the pupa (chrysalis), and the adult butterfly.

The beginning of this 4-stage life cycle begins as it does with most other insects and animals.  With the male and female fooling around.  The Monarch males are real macho, caveman-type studs.  When the mating seasons begins the male will grab any female he can find, latch onto her and carry her up into a tree where they may go at it for hours, even throughout the entire night!  Once the male has had enough of the female he quickly drops (literally) her and goes on the prowl for another.  This goes on until the females decide they’ve had enough (and are full of sperm) and the migration begins.

The egg stage begins with the female laying eggs.  She can only lay one at a time but she can lay 200 to 400 or so a day.  As she lays the eggs she fertilizes them with the sperm she has stored.  However, she must find a milkweed plant on which to lay the eggs.  If the female lays the eggs on any other plant the caterpillars will die after being hatched.  It takes about 4 days for the eggs to hatch.  The females do not live much longer after laying their eggs.

Milkweed is toxic to most birds and other insects, which helps protect the eggs from predators.   The female doesn’t lay all of her eggs in one place.  She scatters them around as much as possible.  Again, this helps to protect them, not only from predator birds and insects but also from other Monarchs, even the mom herself!  Yes, they are cannibals.  Monarchs will eat their own eggs.  Once hatched, the larvae will also eat other nearby eggs. 

The caterpillar larvae that hatch from the sesame seed-sized egg will feed exclusively on milkweed (with the exception of possibly eating their un-hatched brothers and sisters).   All they do is stuff themselves with as much milkweed as they can.  As they fatten up they outgrow their exterior skin and shed it (molt), EAT it, and continue growing.  The butterfly caterpillar will repeat this process 4 times.  From larvae to pupa takes about a month.

A pupa (chrysalis) is revealed and when the skin is shed the fourth and last time. The pupa then attaches itself to the underside of a leaf and forms a chrysalis.  This is not to be confused with a cocoon.  The outside of the chrysalis is the skin of the pupa.  After about 10 days the front of the chrysalis splits open and the adult butterfly emerges. 

The adult butterfly cannot fly until its wings are unfolded and dry.  The wings have veins through which a fluid is pumped to inflate the wings to their proper size and shape.

Let’s review what we have learned today:

1.      .     Monarch butterflies like sex.  A lot of sex. 
2.           They are promiscuous and have great stamina. 
3.           The female saves the male’s sperm for later use. 
4.           Once the male has tired of a female he tosses her aside and finds another.
5.           Once the females have had it with the males they leave town, have their babies, and die. 

If only life was that simple.