Caterpillars

Observations, Questions and Commentary

(To compliment "Sam" The Story of a Cecropia Moth)

What can we learn from the ordeals of Sam's life?

HomeCaterpillars

Here is "Little Sam" just after chewing out of his egg. His birthday is June 11th 2010. "Little Sam" is now four days old. He is already eating his fill on dogwood leaves.

Here is Sam in his second skin.

Why do you think Sam looks so different?

In nature color and form are often a direct result of what survives to be passed on to the next generation. Only those traits that give an advantage of survival persist.

What then is the role a dramatically different instar plays in survival of this caterpillar?

June 29th, Sam is just now into the third stage of his life as a caterpillar. New forms, protuberances and colors are seen. In this photo ecdysis has just occured. To the far left can be spotted part of the old dead skin.

Nine days later, Sam is growing. By this time it is clear that Sam is not your normal everyday caterpillar. He is a little different. By now his body color should have changed to green but, instead, Sam remains a striking bright yellow.

Even though his appearance may be more attractive to our eyes and might even be a desired trait in a domestic strain, is this color an advantage or disadvantage to survival in the wild?

Right: Compare how a normal caterpillar looks in it's 3rd instar.

July 11th: Sam is still in his third instar skin. Thirteen days is a little more than average for a cecropia larva to remain in its third skin. As the days pass the blue color is becoming more and more noticeable. Usually this is seen beginning with the fourth instar skin. Perhaps Sam's yellow color is allowing the blue to show up more than a normal green caterpillar's would. What do you think? Remember: both yellow and blue are components of the color green. Normal green body color is a result of a more complete protein utilization in pigment formation than the paler yellow.

Left: The skin is stretched about as far as it can go. Sam must break free and come forth from his confining outer shell if he is to succesfully grow and prosper.

Do we ourselves also need to break free from possibly outmoded shells of ancestral habits and lifelong rituals in order to continue growth as world citizens upon a global stage?

 In his wanderings from leaf to leaf, Sam has come across another colored caterpillar. This one seems even more different than Sam. It is a cecropia moth larva in third instar just like Sam is but has a much darker, almost black, body.

How might this dark color effect survival in the wild? Could it help in not being noticed by predators? To Sam, in his travels, this color difference is not of any great concern.

By the fourth of July, the black caterpillar had shed into a normally colored fourth instar skin.  It seems that, although outward differences were apparent, seemingly different individuals are often pretty much the same inwardly.

Look closely and compare the third instar picture above with the fourth instar pictures below. Can you see the differences?
Hint: Look at the true legs ( just behind the head), prolegs (claspers), tubercles (colored bumps), and spiracles (breathing holes).

Finally, on the evening of July 13th, Sam has shed into his 4th instar skin. He spent all day waiting for the new skin to develop inside. Then, Sam worked the old skin towards the rear, broke free and crawled out.

Views and hues of a pale colored caterpillar.

July 17th: Sam is now four days into his fourth instar time of life.
The interplay between pigment and irridescent color becomes ever more complex.
Here are photos of Sam as he appears in different lighting conditions.
Which one represents the "real" Sam.

Sam showing off his beautiful blue irridescence.This is how he is seen from above in bright sunlight.

Sam is drinking raindrops after a morning thunderstorm

Full sunny conditions appear after the storm revealing a yellow side to his nature.

Above is Sam as the morning sun strikes him from a low angle. You can see the irridescent blue on the back just beginning to reveal itself.

Why do you think cecropia caterpillars have evolved to show lighter blue hues when seen from the top but often look green when viewed from the side or below? Hint: Think of a bird in flight looking for a nice fat caterpillar to eat. Maybe the the light blue is harder for the bird to see looking down in direct sunlight from above. Darker green hues are also less visible viewed from within the shaded canopy below.

Sam is yellowish in color as is this sibling above. How might this effect their chances of survival; of being found and eaten by birds?

Above: Sam is now 8 days into his fourth instar of life. The blue color becomes more pronounced as the days pass. Also, a gradually deepening green ground color is noticed.

Below: As Sam continues to eat and grow, his skin is stretching, allowing more green from his insides to show through.

July 22nd, Sam is found on a bed of silk. He is not moving around or eating. This behavior is a sign of another event in Sam's life.What do you think is going to happen? The next day early in the morning the long wait is over. Within minutes, Sam will be seen in a new skin as he breaks free and crawls out of the old one. Here, the action has started. Compare the upper two pictures. Look at the head and segments. What is going on?

Working free and crawling out of the old skin was hard work. Look how the old dead skin is still fastened to the silk bed. If Sam had not obeyed the inner prompting to spin this before ecdysis he probably would have lost his grip while shedding and fell to his death.

Can you find the old skin exuvia and head capsule in the photos above?

After all this effort, Sam needs a good, nutritous meal. His jaws have not finished hardening, but the caterpillar is hungry. Instinct tells him to turn around. Why should Sam turn around? He does not need to know why; he just needs to follow the command of his being. In doing so, Sam finds a bountiful source of protein: his own skin! Within the hour, the skin is greedily consumed.

Look at this picture of Sam one week after his fifth instar shed. Folds seen on the skin show Sam still has a lot of growing to do. Right now the skin is not filled up. It is like a balloon only partially filled with air. In a few more days the skin will be stretched tight.

He is usually seen eating and is always on the lookout for fresh leaves.

Remember, Sam must eat his fill to last him through until next year and the rest of his life

Sam has pretty much lost his gold yellow color. He is now indistinguishable from the other caterpillars. Does this increase Sam's chances of survival in the wild?

On August 11th Sam is prompted to do something very different from what he has done before. The urge to feel, poke around and pull leaves together is ovwerwhelming.

Silk strands can be seen as Sam obeys the signal within to spin his cocoon. As Sam progresses the task becomes ever more complex. After a hard day of work, a complex cocoon will have been spun.

HomeCaterpillars

A personal statement about myself.

I have had a deep fascination with insects, especially Lepidoptera (butterflies and moths) literally since kindergarten. Instead of playing “Cowboys and Indians” with the neighbor kids I was out in a nearby field poking around at all sorts of critters. However, it was always the mystery of the beauty and flight of the butterflies that deeply absorbed my attention.

It really was an all consuming passion. Early grade school years saw me collecting butterflies and then going to the college library to classify them. When it was possible to travel a little south of northern Minnesota it was challenging to see if I could find hybrids of white banded and red spotted purples. I thought about things like,” Female white morph sulphur butterflies are so common; why can’t I find any white males?” and so on.

One outcome of this rather eccentric childhood is this current website.