Many plants protect themselves from herbivory with toxic chemicals. However, some herbivores not only tolerate these compounds, but also actively sequester them to become distasteful themselves. For example, caterpillars such as monarchs (
Danaus plexippus) and queens (
Danaus gilippus) prefer to feed on milkweeds, which contain toxic cardiac glycosides. Nevertheless, this dangerous diet does not deter all the caterpillars' potential
enemies. One day when I went to check on the caterpillars, I found a
parasitoid wasp roaming the milkweed plant.
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| A parasitoid wasp on a milkweed stem. |
With its antennae twitching up and down, the wasp walked along the milkweed stem...
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| The wasp walking along a stem above a queen caterpillar. |
...and gradually closed in on one of the queen caterpillars.
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| The wasp perched directly above the queen caterpillar. |
When the wasp reached the end of the stem, it appeared poised to descend and parasitize the caterpillar. Yet, anticlimactically, the wasp flew off and the caterpillar continued eating the milkweed in peace.
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