[Odonata-l] rain barrels and mosquito control

[Fred SaintOurs]

Speaking of drought, I had a very positive experience with rain barrels recently. One day in June I was able to collect over 300 gallons in half an hour off one side of my house (using 6 barrels linked in pairs by siphon hoses). Within two weeks they were filled with mosquito larvae. I contemplated collecting dragonfly larvae to add to the mix, but questioned their effectiveness as well as my ability to see to it that they survived to adulthood. 
Instead I went to the local pet store and bought 6 "goldfish", the plain grey feeder-type that cost about 20 cents each and usually end up as Oscar-chow. I put three in one barrel, and the next day there was not a single insect left. I transferred them to another barrel, with the same results. Finally on the third day one fish died, and from a brief "oste-opsy" on my picnic table I determined that it's gut had exploded!  
In another barrel I put only one fish, and there were only a few mosquitos left after two days. Very effective, very cheap, and no chemicals necessary! Dead fish also make great fertilizer!

FS

----- Original Message ----- 
  From: Steve Collins 
  To: 'Odonata-l' 
  Sent: Wednesday, July 04, 2007 11:25 PM
  Subject: Re: [Odonata-l] drought areas in US


  Dave,

  You would find that many rivers and streams are more flashy now, with contributing watersheds composed of more impervious surface and other landuse changes condusive to increased runoff.  Many USGS data sets indicate this, despite the advent of stormwater management.  I don't know about the rainfall intensity itself, however.

  Cheers,
  Steve Collins
  Towson, MD

  Dave McShaffrey wrote:

    Drought is a problem for sure, but I think there is another subtler problem in the works for the odonates.  I can't prove it, but it seems to me that when it rains now it really rains hard, and these spates are causing rivers to rise and fall quickly.  A river that rises quickly has the capability to wipe out a whole generation of emerging odonates along its banks.  I think for some of our river species the unpredictability of river levels may be just as important as drought.



    I suppose if one had time one could use the USGS sites like this one:



    http://waterdata.usgs.gov/oh/nwis/dv?cb_00065=on&cb_00060=on&begin_date=1998-10-01&end_date=2007-07-03&site_no=03115400&referred_module=sw



    to see if things have really changes over time.  Of course, this particular site only has height data going back to 1998.  Still, a random sampling of sites with a longer period of record might turn something up.  I small a MS thesis in here somewhere.



    Dave 



    Dave McShaffrey

    Marietta College

    (740) 376-4743

    www.marietta.edu/~mcshaffd
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