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Spraying for West Nile and diminished insect population.

 
 
Reply Wed 6 Jun, 2018 01:45 am
To those who live in areas sprayed for West Nile, have you noticed a diminished population of butterflies and other flower-pollinating insects, as well as the flowers themselves? I'm talking about the reduction of the population of insects overall as a result of spraying for mosquitoes.

I walk about a mile and a half a day in a wild area near my house dominated by invasive Ligustrum sinense (Chinese privet), but there are also a number of meadows dominated by native plants that flower profusely in the spring. Of note are Antelope horns, Asclepias asperula, a milkweed with flower heads that resemble  green tennis balls. In most years these flower heads are full of hairstreak butterflies, bumblebees, and large milkweed bugs. In previous years I would see at least a dozen of each of these species during one of my daily walks. This spring, total, I've seen a total of two or three bumblebees, two or three milkweed bugs, and zero hairstreak butterflies.

Other species of butterflies are lacking as well. I've seen no swallowtail butterflies of any species, no pearl crescents, no variegated or gulf fritillaries, no American or painted ladies, no red admirals, no hackberry butterflies, 1 or 2 yellow Sulphurs, and no buckeyes, though it's early in the year for those. Honey bees also seem few and far between. I have two tickle-tongue trees, Zanthoxylem clava-herculis, in my yard that are usually preyed upon by caterpillars of the giant swallowtail butterfly. I normally see a half a dozen or so of these caterpillars a year, but this year none so far.

http://farm7.staticflickr.com/6198/6073343296_75702f4e07_z.jpg
Caterpillars giant swallowtail butterfly, a welcome sight anytime.

There is a rain-fed tank that normally has several dozen dragonflies everyday, but this spring there are only three or four at a time. ( a tank is an artificial pond originally dug for cattle.)

As far as flowers go, the Larkspurs (Delphinium spp) normally number in the hundreds in the spring, this year, one flower. Can one attribute the disappearance of this flower, to the diminished insect pollinators?
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Type: Question • Score: 5 • Views: 561 • Replies: 8
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rosborne979
 
  2  
Reply Wed 6 Jun, 2018 04:34 am
@coluber2001,
How do you know the changes you see are caused by the spraying and not something else? I’ve seen changes in insect populations around here, but there is no spraying going on.
coluber2001
 
  1  
Reply Wed 6 Jun, 2018 01:08 pm
@rosborne979,
I don't know if it's the spraying for mosquitoes. It's just a guess, because it's the only idea I've come up with, and I'm open to other suggestions. There's no drought, and temperatures are normal.

Last year there was a lessening of insects, but this year it's almost catastrophic, and I don't think anybody notices. It's only that I'm out everyday and look forward to the spring spectacular. It's such an extreme shift that it's impossible for me to ignore or accept.

What's sad is that so few people are aware that it's happening or even care that it's happening, and that so many people would accept these consequences for protection from a minor disease like West Nile.

Like I said, it's just a guess that it's the spraying that is causing the problem, but it could actually be symptomatic of something much worse. Do you have any ideas?
farmerman
 
  1  
Reply Wed 6 Jun, 2018 08:02 pm
@coluber2001,
I overplant dill, cilntro and fennel just so the various swallowtail species can go through their life cycles. Ive got an asclepsis row of A Indica where Ive been breeding the monarch. The farmer who cuts and teddies my hay fields knows that weve dedicated the outer two rows of grass and alfalfas nearest streams and creeks to the milkweeds.

It hAS BEEN a wet and ovrall cool spring( for us this favors deer ticks but not butterflies). Ive been told that, down in the Chesapeake and Ocean City Md, the skeeters and greenhead biting flies have gotten an early start that its difficult to sit outside in the evenings without needing blood .

I do not allow nicotenoid ag chemicals and my Amish neighbors are all organic dairymen so the honeybee dieoffs due to hive collapse and mite problems as well as dieoffs in other complete metamorphosis pollenators and the rarer skippers and blues arent as severe as in some other areas (like down in the Eastern Shore of the Chesapeake)

Many of the ag chem dealers give free samples and loads of chems if you buy Roundup Ready grains or other chem resistant seeds
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rosborne979
 
  1  
Reply Wed 6 Jun, 2018 08:11 pm
@coluber2001,
Animal populations go in cycles around here, and it's not just insects. We have years with tons of chipmunks, and then other years with very few. Same for deer and squirrels and birds of various species. We also have years with lots of mosquitos or few mosquitos. For the most part I think it's just population cycles because they are all connected to each other. The chipmunk cycle seems to be related to the acorn cycle. Lots of acorns one year means lots of chipmunks the next year. Then lots of foxes and hawks, then fewer chipmunks.

Maybe the spraying is having an effect on things, but it's very hard to differentiate between causes.
roger
 
  1  
Reply Wed 6 Jun, 2018 08:39 pm
@rosborne979,
My house was crawling with little web spiders a few years ago. We still get a few travelers crawling around, but none in webs. This year is a bit dryer than usual, but I can't see that accounting for the difference.
rosborne979
 
  1  
Reply Thu 7 Jun, 2018 04:28 am
@roger,
I can’t either. More likely you simply had an egg sack hatch in there a few years ago.
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coluber2001
 
  1  
Reply Wed 13 Jun, 2018 04:13 am
These are the approximate numbers of individuals of given species of butterflies and other insects I have seen in a typical spring in past years and this year.

       past years.             this year

leafwing.          3.              0
swallowtails.  40.             0
hairstreaks.     200.          0
question mark 200.          2.
var. frittilary.     50.            0
gulf frittilary.     30.            0
pearl crescent.  100.         0
yellow sulphur.  100.         10
hackberry.          100-500.  0
buckeye. 50. 0
dragonflies &   1000-5000  300
damselflies

large milkweed
bug.                      300.           10
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hightor
 
  1  
Reply Wed 13 Jun, 2018 04:22 am
Meanwhile, over in Germany:

Insects decline dramatically in German nature reserves: study
0 Replies
 
 

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