Thursday, August 9, 2012

The painted lady in distress

At the butterfly garden, monarchs weren't the only butterflies to find their favorite plants.  Painted lady butterflies (Vanessa cardui) had also been attracted to the garden and were busy drinking nectar from the many flowers.

Painted lady butterfly (Vanessa cardui) drinking nectar from a coneflower (Echinacea sp.).
Whereas monarchs specialize on milkweed, painted ladies prefer thistle (in fact, they are also known as 'thistle caterpillars').  Even when small, the caterpillars can be located easily due to the white silk 'tents' that they weave around themselves.  Once a caterpillar has eaten enough thistle, it forms a chrysalis and begins its metamorphosis into a butterfly.

Painted lady chrysalis (Vanessa cardui) hanging on a thistle, surrounded by silk webbing.
However, the tent does not protect the chrysalis from all enemies.  I found one chrysalis swaying in a gust of wind.  I waited until the wind died down so that I could get a better picture.  Surprisingly, even when the wind stopped, the chrysalis was still shaking violently.  Looking more closely, I saw that there was a small wasp sitting on it.

Painted lady chrysalis (Vanessa cardui) being parasitized by a chalcid wasp.
It was the touch of this wasp, a parasitoid of the painted lady, that was causing the chrysalis to shake.  If the wasp succeeded in laying its eggs despite the shaking, then in a few days it will be a new generation of wasps, not a butterfly, that emerges from this chrysalis.

Explore some more:
Charlotte Rhoades Park and Butterfly Garden

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