Monday, May 28, 2012

Milkweed and Monarch

Judging by the numbers of larvae currently present, Monarch butterflies are going to be particularly abundant this summer.  Strong southerly winds and warm temperatures brought this migratory butterfly to Blue Jay Barrens much earlier than normal.  I’m looking forward to having this species as company through the summer.

The Monarch butterfly was partly responsible for what people referred to as my poor attitude towards school.  In our fifth grade science text, the developmental stages of a butterfly from egg to adult were exclusively portrayed by the Monarch butterfly.  When the teacher distributed drawing paper and asked us to draw those stages, the entire class reproduced the illustration of the Monarch.  Except for me.  I chose to illustrate a Black Swallowtail, a species that I had raised on Wild Carrot during the summer.  The teacher used the text illustrations to show how inaccurate my drawing was and explained that what I portrayed could not exist.  I decided that if she could be that wrong about butterflies, she was probably just as wrong about everything else she was telling us, so I stopped listening to her. 

Monarch caterpillars feed on Milkweed leaves.  A single Common Milkweed sprouted near the Water Garden a few years ago and has since developed into a nice clump.  I see it every day, so it’s easy keep track of any changes.

Fras accumulation on the leaves told me that there were caterpillars at work. 

Fras is also known as caterpillar poop.  Caterpillars spend their lives taking in plant material and expelling waste.  In a search for caterpillars, it’s often easier to find the fras and then trace that back to the animal.

Loss of plant parts is another indicator of caterpillars at work.  Newly hatched caterpillars often have trouble eating mature leaves.  Newly formed leaves, like those found sprouting from the leaf base, are much easier to consume.  A missing sprout is often caterpillar sign.

Holes or missing sections of leaf can also be the work of caterpillars.

Just looking on the other side of the leaf reveals the culprit.

The pattern of feeding is often a deliberate attempt to stop sap flow into the portion of leaf being consumed.  A damaged Milkweed leaf often releases the sticky sap.  By isolating a section of leaf, the caterpillar can feed undisturbed by the sap.

Not all holes in a leaf represent feeding damage.  Jagged tears or holes, especially those with ragged bits of leaf remaining, are examples of physical damage.  In this case, the leaves were battered by a hail storm.

Flowers are also a choice target for smaller larvae.  Some species of moths and butterflies actually lay their eggs on the flower buds. The young can begin feeding on more delicate parts before moving onto the tougher leaves.

Many insects avoid detection by remaining on the under side of leaves, so always get your head down and look up.  I watch many people examine a plant by staring at it as though it was a picture.  Plants are three dimensional objects that require examination from various angles.  Don’t forget that our bodies are supposed to twist and turn.  Use that ability to avoid missing some of the wonderful things in nature.