[Odonata-l] Strange Larval Behavior

[Glenn Corbiere]

Bob - To me, it sounds like it just wants to look and see where it might be heading next.  I usually try to do the same thing myself, although to my detriment, not in every case when persuing its kin!
   
  Glenn
   
   
  

Bob Glotzhober <bglotzhober at ohiohistory.org> wrote:
        st1\:*{behavior:url(#default#ieooui) }                I have been trying to rear an anisopteran larva taken from Big Darby Creek, just a little west of Columbus. I have not tried to force it through a key as I’m hesitant to manipulate too much while it is alive and earlier instar exuvia have not survived well prior to me finding them floating in the container. However, I believe it is likely Nasiaeschna pentacantha, the Cyrano Darner. When collected it had two light spots on the dorsal surface of the abdomen segments 6 and 7. Andrew Boose also had one – more mature than mine, and his has emerged in a normal fashion. His maintained the two dorsal spots through to its final instar, mine has lost them and is uniformly dark brown (last time noted with twin spots was about F3, last October). When I collected it (Sept.6, 07) it was an estimated F5 larvae and 9mm long. It has molted five times, and I believe it is a final instar with a head width of 7.2mm, total length of
 28.5mm and a hind wing sheath length of 4.8mm. It is a female larva. The ID is very tentative for now – but that is not the question I have.
   
  Mine has been in what I believe to be the FO instar stage since June 5th. I have a branch in the container that it can climb up on. It eats well, though this has slowed down during the last couple of weeks. For at least a month or longer it has been crawling part way up the stick. (Sorry, I’ve been so busy with other projects, I failed to record when this behavior started.) I am accustomed to FO larvae doing this for a week or two prior to molt, leaving (initially) the last half of the body, or (toward the end) the tip of the abdomen in the water. This one has been observed for long periods totally out of the water. I was concerned it was dead, but it readily moves to avoid me if I touch it. More problematic, not only does it sit totally out of the water, but sometimes it head-first, and sometimes it sits totally out of the water and upside down  -- i.e. head pointing toward the water. I’ve never seen this behavior before, nor recall reading anything like this.
   
  So I have this upside down, out of water behavior in addition to a very prolonged period of time after initiation of out-of-water behavior and it has still not molted into the adult. Any comments, references or thoughts are appreciated. Just what is going on here?
   
  ====================
  Robert C. Glotzhober             614/ 298-2054
  Senior Curator, Natural History         bglotzhober at ohiohistory.org
  Ohio Historical Society         Fax: 614/ 297-2546
  1982 Velma Avenue
  Columbus, Ohio  43211-2497
   
  Visit the website of the Ohio Historical Society at:
    www.ohiohistory.org and check out our online collections catalog.
  See or purchase Dragonflies and Damselflies of Ohio or the Cedar Bog Symposium II at OHS's new E-Store:  http://www.ohiohistorystore.com/ 
  Visit the Ohio Odonata website at:  http://www.marietta.edu/~odonata/index.html
   
   
   

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Glenn Corbiere 
100 Prospect St. 
Chester, MA. 01011-9657 

www.dragonhunter.net 






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