Saturday, August 28, 2010

Yellow Butterfly Population Explosion

It happened again this week, the second time this summer.  Hundreds of Clouded Sulphur butterflies floated over the alfalfa fields and puddled along the roadsides in west-central Wisconsin.

They frequented the goldenrod nectar bar too.

Clouded Sulphurs are one of the most common butterflies in Wisconsin.   They've been spotted as early as March and as late as the first week in November.  They have several broods in a season and overwinter here - but not as an adult. 
The last time these insects caught my attention, I wondered why haven't I seen any predators feasting on them?

I pulled to the side of the road and looked for predators and signs of predation.

I found dozens of yellow butterflies, hit by cars, dead on the road.  I also found little piles of wings (with no bodies) - but saw no predators (birds, dragonflies, frogs, rodents and mantids) in action until we were just about ready to head back home.

I stopped to take this picture of a very small and flitty, Eastern Tailed Blue. 

It was hot (87-degrees F) and the mosquitoes were merciless, so I gave up with the photography and headed back to the Prius.  As I was buckling in, my husband said:  look - there's an Eastern Phoebe, eating a sulphur!

We watched as the phoebe grabbed one of the sulphurs "puddling" just a few yards from the car.  The flycatcher whacked it on the ground and left the wings behind as it flew off to perch in a nearby tree.

Other sightings:

American Lady
Gray Comma

Red Admiral
Cabbage White
Hackberry Emperor
"Summer" Spring Azure
Question Mark

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