Readers’ wildlife photos

It’s time for me to importune readers to send in your good photos. To put up a wildlife post nearly every day does require the assistance of photographers!  And your photos will get an appreciative audience of nearly 55,000.  Today we have some photographs from Mark Sturtevant, sent in mid-February. This continues the developmental cycle whose first stages were presented here.

Here is the final stretch of pictures from last summer where I raised several hickory horned devils, which are the giant larvae of the royal moth (Citheronia regalis) . The first two pictures show where we left off last time, which was at feeding 4th instar larvae. They were pretty big by then, but soon they would get a lot bigger.


I had been trying to get pictures of a 4th instar larva molting to the final (5th) instar, and here at last I had success! Commitment to molting starts when the larva stops feeding and assumes a distinctive ‘premolt’ position. I can then set them up in our dining room in front of the camera, and they will not leave the perch for up to several days until they molt. In the second premolt picture the cuticle is visibly wrinkled, meaning they have separated their old cuticle from the new one which is underneath. I was pretty much freaking out at that time since I was not about to let this one slip past!

The next several pictures show the full molt process, with the old cuticle splitting, and emergence of the 5th instar. The additional broad white stripes that appear down the sides are the old cuticle that had lined the system of tracheal tubes through which the insect breathes. They too are being stripped out. In the final pictures of this sequence the larva pulls free, and then comes to a rest. The whole sequence, once begun, only took several minutes. Post-molt larvae will sit like this for several hours as their new cuticle hardens, then they start to move again and their first act is to eat some of the old cuticle. Note that by then the horns are well pigmented.

At about this time I stumbled across a simple method to make gif animations in Gimp, which is the free photo editing program that I use to process pictures. So next is an impromptu gif animation of the complete sequence of a hickory horned devil molting. Not many people get to see this!

At first, the newly molted 5th instar larvae were the predominantly brown color that dominated their earlier instars. It must be admitted, however reluctantly, that they are not terribly attractive through that extended time. But that soon changed dramatically as the 5th instars resumed their feeding and took on their characteristic green color. As a bonus, before taking on their final color many of them temporarily turned bright yellow. That is actually my favorite ‘look’ for these larvae, and the picture of the yellow 5th instar is actually one of my favorite buggy pictures from last summer.

Next are pictures of green 5th instars. Their increased appetites at this time meant they were more demanding. The large bundles of leaves that I could collect from local black walnut trees used to be sufficient for several days, but now they were barely sufficient for one day. The poo also accumulated at an impressive rate, and their audible ‘announcements’ were hard to ignore. The caterpillars were kept in a series of large plastic containers, each stuffed with a bouquet of leaves. Every few minutes anyone in the vicinity of the dining room area would hear a “Plink!” or “Plunk!” as kidney bean sized droppings hit the bottom. It was… a subject of some conversations during dinner.


The larvae attained their maximal size after a bit more than a week. I never measured them, but they are described as getting to 6 inches and I can well believe it. During sessions when I extracted a couple giants from their container to photograph, I could generally rely on them eating during the entire time. They were pretty intent on packing it in.

Then it all started to change. One by one, the larvae would lose interest in eating as they began to prepare for metamorphosis. The sign of this new phase was when a larva would descend from the leaves to wander around the bottom of their container. As the days passed I would generally find one or two that had reached that point. The wandering larvae would also turn a pretty blue color, which is an optical effect from the brown pupal cuticle developing underneath their larval cuticle. This is shown in the next picture with a bunch of blue and green larvae in my hand. This is actually an old picture from some years ago when I had first raised a batch of devils.

Hickory horned devils do not spin cocoons. Instead, they burrow in the ground and later pupate there. I had learned from prior experience that trying to get a large number of giant larvae to pupate naturally in the dirt was just not workable because they would invariably interfere with one another under ground. The procedure that worked for me was to first let the wandering larvae just walk in endless circles in a large bucket in a dark basement for several days. Their muscles would gradually break down, immobilizing them, and they would dramatically shrink in size as shown in the next picture.

Once a larva could crawl no longer (and disturb other pupating larvae), it was then buried in a ‘grave’ in a large tub of dirt, next to other immobile larva. The caretaking demands declined as more larvae went into the ‘pet cemetery’. I have always experienced a feeling of ennui at these times when my task of raising Saturniids was coming to an end. My children were growing up and I was no longer needed.

Where things stand now is that I have several devil pupae in the dirt, in a large cage that is kept at room temperature. The last time I tried this I made the mistake of refrigerating the pupae so that they might emerge next Spring. This is what I would do with other Saturniids, but none of the devil pupae from that batch survived. That actually makes sense (in hindsight) since they are a warmer-climate species. The last picture shows the pupae from that ill-fated batch, tastefully displayed in a dessert dish.

If I get any moths, I will of course take more pictures. Fingers crossed!

22 Comments

  1. Posted March 26, 2018 at 7:37 am | Permalink

    Those are creepy.

  2. GBJames
    Posted March 26, 2018 at 7:43 am | Permalink

    I’m looking forward to the moths.

  3. Posted March 26, 2018 at 7:52 am | Permalink

    Good luck Mark!! When I was a kid I used to keep mine in a cool basement over winter, and that worked well.

  4. Jonathan Wallace
    Posted March 26, 2018 at 7:53 am | Permalink

    Great series of photos Mark! I loved the gif of the moult (molt to you, I guess!). How many individual photos were used to create that?

    • Mark Sturtevant
      Posted March 26, 2018 at 8:01 am | Permalink

      Thank you. I count 38 pictures of the entire molt process. I was not planning to put it into a gif. If I knew in advance, I would have backed off the camera a bit to make sure that it stayed in frame the whole time while molting. But in this series I was moving the camera around best I could.

  5. jaxkayaker
    Posted March 26, 2018 at 8:00 am | Permalink

    Excellent photos and kudos for your efforts raising the little devils.

  6. Debbie Coplan
    Posted March 26, 2018 at 8:37 am | Permalink

    What a fascinating post, wonderful photos and gif animation. Thank you!

  7. busterggi
    Posted March 26, 2018 at 9:18 am | Permalink

    DNA-wise, how closely are these related to Mothra?

  8. Posted March 26, 2018 at 9:58 am | Permalink

    Glad I read this post AFTER breakfast!

  9. cruzrad
    Posted March 26, 2018 at 10:25 am | Permalink

    Wonderful post Mark. Thanks.

  10. Posted March 26, 2018 at 12:36 pm | Permalink

    “Metallic green”, like on the ducks. Interesting.

  11. Heather Hastie
    Posted March 26, 2018 at 2:52 pm | Permalink

    What an enjoyable and interesting post! Great pics too. Loved the gif. Thanks Mark! All the best for the next stage! I can’t wait!

    • Mark Sturtevant
      Posted March 26, 2018 at 3:28 pm | Permalink

      Thanks! I will do my best.

  12. Mark R.
    Posted March 26, 2018 at 4:11 pm | Permalink

    That was an amazing group of photos. Your dedication and diligence really paid off. Glad you didn’t miss the molt this time!

    Iirc, you said the last molt you missed took a few seconds. Is that how fast this was since you were looking at it this time?

    I imagine with appetites like these giants, a large group of them could wreak havoc on a black maple tree.

    • Mark Sturtevant
      Posted March 26, 2018 at 7:10 pm | Permalink

      It takes a few minutes — but very few, if I recall correctly. Not doubt this was a factor in my missing several of them!

  13. Posted March 26, 2018 at 5:16 pm | Permalink

    Holding thumbs for the arrival of the moths. Great sequence of pics.

  14. SusanD
    Posted March 26, 2018 at 5:19 pm | Permalink

    Top marks! Absolutely wonderful photos and narrative. Looking forward to the moths.

    • Glenda Palmer
      Posted March 26, 2018 at 5:55 pm | Permalink

      +1

    • Posted March 27, 2018 at 6:53 pm | Permalink

      + Another. Those prickly things would scare me, even if they are false advertising and not poisonous. Would the prickles even bother a bird? Why bother, I wonder.

  15. Posted March 26, 2018 at 7:29 pm | Permalink

    Really lovely gif and caterpillars. Good luck with the moths!

  16. Andrea Kenner
    Posted March 27, 2018 at 5:53 am | Permalink

    Wow! Nice work!!!

  17. Posted March 27, 2018 at 5:59 pm | Permalink

    This is pretty amazing stuff.


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