Naturespeak A naturalist's view of the world

July 21, 2007

Both Ends of a Butterfly

Filed under: Uncategorized — wykes @ 10:17 pm

You could say that a story fell into my lap yesterday evening.  Well, if not exactly “fell” and not exactly into my “lap,” a freshly dead Red Admiral Butterfly offered itself to me. O.K., it didn’t technically offer itself either, but was there on the nature trail for me to discover. Its delicate wings were only slightly worn about the edges and the external body undamaged, so I took it in for a closer look.  I suspect a hungry Kingbird crushed the butterfly and accidentally dropped it – perhaps frightened by my approach.

  Earlier in the week, I had managed to sneak a close look at a Monarch Butterfly as she went about laying her eggs.  After several attempts, I managed to snap a shot of her in the act. Now I was presented with a week where I was witness to both the beginning and the end of butterfly’s life (two species, but both of the aerial butter persuasion). Here was an opportunity to pay attention to both ends of this insects life and anatomy.

  Take a look at my photo of the female Monarch laying an egg. Upon landing on the chosen milkweed leaf, she side stepped off the edge and curled the end of her abdomen around to come in contact with the underside. After a few seconds of blindly searching around with her ovipositor (egg laying organ) she placed a single egg on the leaf and promptly flew off.  She repeated this exact procedure multiple times while selecting different leaves in the milkweed bed, so I witnessed at least 10 egg placements within a few minutes. Over the course of her brief life, she will potentially lay over 300 eggs (one captive individual laid 161 in a single day).

  A little appreciated feature of this simple act is that the eggs are actually glued into place. Monarch Glue puts Gorilla Glue to shame. Take a look here to see a detailed view of a monarch egg (in actual scale they are only 1.2 mm high).  Note that there is a ring of bubbly dried glue at the base of the shell where it contacts the leaf.  As each egg travels down the ovipositor tube on the “way to the lay” it is positioned blunt end first.  It passes by a pair of glue glands where a sticky drop is neatly placed on the bottom and the package is lightly pressed into position.  The thick glue “fixes” immediately upon contact with the air, so our female is careful not to get any on her hind parts.

  Although this particular female can only expect to live a maximum of five weeks, her eggs will carry Monarch life into the following year. Held by glue and protected from weather on the underside of the leaf, the eggs need to remain in place for four days before they hatch.  These July eggs will result in hungry caterpillars and September adults that will migrate and survive into the next spring.

  From the beginning of one life out of the end of one butterfly, we now look at the beginning portion at the end of another. Any Red Admiral butterfly flying in late July should also expect to survive into the following year.  These cold hardy beasts hibernate through the winter as adults. My Admiral met a premature “end”, which led me to momentarily wonder if it was actually a “rear” Admiral (that was a small joke, by the way – usually annotated with a wink of the eye and the repetition of the words “end” and “rear” several times).  As a means of recovering from such a pitiful attempt at humor, let me state that the name of this species stems from the prominent red stripes on the upper wings. These marks faintly resemble the red chevrons found on the old naval uniforms of British Admirals.

  Take a gander at the underside of the dead Admiral’s wings in my photo for another point of view. Note the subtle orange, blue and black patterns and the micro wing scales rubbed off on my thumb. The proper way to hold a living butterfly, as well as a dead one, is to firmly grip the wings in this manner so that they don’t shift about and shed too many of their scales.  As a member of a group called the brush-footed butterflies, the Red Admiral clearly displays his set of soft bristled front feet in this view. 

  The next step in our discussion involves a pin, but not in the manner you might think. Ahead of the prominent eyes, there is a pair of fluffy face pads called palps which protect the delicate tongue which is at the leading end of all butterflies. In order to see that miraculous organ we need to gently tease it out.  Take a look at these two photos (here and here) and you can see how this is done.  The tongue is coiled up like a party favor when not in use and the prodding of the pin can be used to unroll it for full view.

  The Admiral’s tongue is nearly half the length of its body.  It is hollow down the center and engaged like a straw for sipping fluids.  Take a look at this fantastic micro view of a Monarch tongue and you can see the tubular structure.  In cross section, these tongues are actually pinched down the middle and function as side to side double straws.

  As impressive as the Admiral’s tongue is, it is fairly short when compared to other butterflies.  Longer tongued species like the Monarchs and Painted Ladies, can feed on deep tubular flowers.  Middle range straws are found on Swallowtails and Cabbage Whites for nectaring at shallow flowers.  The Short- tongued Brushfooted butterflies don’t feed at flowers.  They only need an organ long enough to lick the surface of sap flows, rotting fruit and animal poop.  Yes, the Red Admiral is a Rear Admiral after all.

  So there you have it – the story from beginning to end.

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