[Odonata-l] Absent nymphs

Dennis Paulson dpaulson@ups.edu
Wed, 18 Jun 2003 09:24:49 -0700

Joe Ackerman wrote:

>I have been sampling retention ponds for Odonata for 2 full summers. 
>This spring,  a large pond is completly void of all forms of Odonata 
>nymphs.  The pond is 2 meters deep and about 4 acres in size with 
>cattails around the shoreline. Over the last 2 years 7 species of 
>Zygoptera and 6 of Anisoptera have been found, and always by this 
>time of year.
>The only thing I can think of is winter kill due to a hard winter 
>but the rest of the insect population seems intact as does the fish 
>Has anyone seen this sort of complete change from one year to the next?

Joe, I've never heard of such a thing.  If the fish and other insects 
are still there, I can't imagine a reason the odonates aren't; it 
obviously didn't dry up.  It represents a real anomaly to me, and I'd 
be interested to hear what transpires during the rest of the summer.
Dennis Paulson, Director                           phone 253-879-3798
Slater Museum of Natural History                 fax 253-879-3352
University of Puget Sound                       e-mail dpaulson@ups.edu
1500 N. Warner, #1088
Tacoma, WA 98416-1088