At our Florida winter home, I often encounter a large tiger moth caterpillar at Wildflower Preserve just off Gasparilla Island, identified as the salt marsh caterpillar.
This is not an appropriate name since this moth is widespread in the east.
But I never saw the adult until I returned to our Virginia farm where a beautiful white moth appeared on our window one morning recently. This is a female tiger moth since the hind wing is white, not yellow as in the male.
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A large tiger moth caterpillar at Wildflower Preserve just off Gasparilla Island.
When I poked the moth it raised its wings and revealed a brightly colored abdomen in a most interesting display. This would seem to indicate to potential predators with color vision (birds especially) that this moth is distasteful or toxic
On checking references I found the caterpillar consumes plants such as dog fennel in Florida, which contain toxins (pyrrollizidine alkaloids) it retains as protection and strangely enough as raw material to make male sexual pheromones.
So in this case we find another of many examples of the evolutionary results of the "arms race" between predator and prey. This also indicates how pervasive the effects of predation are - so much so that a complex set of behaviors, morphologies and biochemistry are involved in providing protection for this beautiful moth.
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William Dunson, Ph.d., professor emeritus of biology at Penn State University, splits time between Southwest Florida and his farm in Galax, Va. He can be reached at wdunson@comcast.net.
