Readers’ wildlife photos

October 4, 2014 • 4:51 am

Reader Mark Sturtevant sent a nice sequence of a caterpillar molting (species not identified). His notes:

My cecropia caterpillars are now pretty huge, and they are not done growing. I had earlier taken some photos of a cecropia caterpillar 4th instar larva as it was molting to the 5th instar. I thought they turned out pretty cool, and I hope you enjoy them, but my Maru’s Syndrome is such that I must also provide a mini-lecture. Sorry about that! The pictures were taken with my trusty little Nikon Coolpix camera.

  1. The larva has been motionless on this twig for at least 2 days, and is committed to molting. It will shed essentially the entire cuticle in one piece, and this includes the cuticle that covers every appendage, bristle, parts of the gut, and even the respiratory system. Insects do not have lungs, but rather do respiration through a branching network of cuticle lined ‘trachea’ tubes that extend from the spiracles. The spiracles are the white ovals on the sides of the body segments. Other items to track are the abdominal prolegs. The larva is hanging on by these. Finally, there are the colorful tubercles on the larva. You can see that the black spines on the tubercles have already been replaced with a set of new spines inside the tubercles. [JAC: click to enlarge photos.]

1Premolt

  1. The old cuticle has separated. Peristaltic waves of contractions are moving up and down the body.

2Molt

  1. Strreeetching forward! Here you can see old trachea cuticle being pulled out through the spiracles. I am not sure how easy it is to breathe during this time. You can also see new tubercles being dragged forward under the old cuticle. Three of the five paired prolegs are also pulled free, so the larva is counting on the old proleg cuticle to help it hang on. This is one reason why molting seems to be a pretty dicey process.

3Molt

  1. The 5th instar is starting to emerge.

4Molt

  1. I am always reminded of a pastry chef squeezing cake frosting out of a tube when I watch this. The old head capsule has dropped off. You can see that the 5th instar looks a little different from the 4th instar.

5Molt

  1. Almost done! Sometimes I can see the hindgut cuticle being stripped out of the rear end.

6Molt

  1. Finished! Starting with the forward stretch, the process of molting takes about 15 minutes. After a molt, a larva will hang out for a day or so before it resumes feeding.

7Molt

Finally, for those of you who need your weekend bird fix, here are three pictures of female ruby-throated hummingbirds (Archilochus colubris) from Diana MacPherson. I have a strong temptation to designate hummingbirds as Honorary Cats, but that distinction must go to owls.

A  couple of different sides of the same female ruby-throated hummingbird as she looks around while sitting on a moonflower vine guarding then nectar. The feeder is just below her & if another female comes by, she goes after her. The male ruby-throated hummingbirds are gone now for the season and there are just the females left with scarcer nectar supplies.

 

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16 thoughts on “Readers’ wildlife photos”

  1. So, what’s with the spiny pokey bits that seem to be all the rage in caterpillar fashion?

    1. To answer my own question, some of the tubercles are defensive (especially in the hairier caterpillars), with either sharp and sometimes poisonous bristles or fine hairs that can brush off and irritate the eyes, mouth, and throat of a predator. A few tubercles help caterpillars hold on. And a rare few serve as FM radio antennae.

      1. Yes. And their radios will be tuned to NPR. The spines in cecropia caterpillars are only mildly scratchy, but I suspect they would be pretty irritating when swallowed.

  2. I wish I could moult my old skin and emerge a shinier, more radiant version of my old self.

    1. Me too & you could have fun with the cast off skin. You could put it places to startle people or put it in the passenger seat of your car so you can drive in the HOV lanes.

  3. Fascinating photos by Mark! My head is all a buzz thinking about rejuvenation/regeneration and its apparent antithesis, aging/degeneration: a continuum wide open to being modified.

    1. Yes, they really do look extra pretty. Of course hummingbirds look all nice and shiny all the time.

      1. They probably molt but they always do look nice. They’ve all gone now. 🙁 I miss them over winter.

  8. The only time I’ve molted is after a really bad sunburn! Ouch.
    Great photo sequence Mark. I really appreciate all your catapilla shots this summer.
    I’ve also enjoyed your hummingbirds Diana. I saw one here yesterday, so they’re not quite gone from the Northwest. Will be soon though 🙁 But I’m actually glad they’re migratory, wouldn’t want them to become boring like the starlings.

    1. Me, too. I molted one summer at age 15 when after having lived in London for 2 years I spent a month in Hawaii with family friends. Ouch! Never thought of sunscreen in those days.

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