Flowers with Sex Appeal

Enlarge Image Image Gallery The Australian wasp orchid Cathy M. Powers/www.Banjorah.com

Imagine you’re a thynnine wasp blithely flying around the Australian countryside looking for a date. You spy what looks like a lady wasp waiting for your approach. It even has an ever-so-pleasant and feminine bouquet. When you investigate further, however, you find out that it’s an imposter  – a flower that mimics a female wasp  – and all you’ve got for your trouble is a dusting of pollen.

What you’ve just experienced is an encounter with an Australian wasp orchid. To carry out its own reproductive cycle (to be pollinated), it has adapted to look and smell very attractive to male wasps. Adaptation to resemble another organism is called mimicry.

Mimics exist in all kinds of places. Scientists have identified several types, most named after the naturalists who first defined them. The flower with sex appeal is a Pouyannian mimic. The fly that looks a whole lot like a dangerous wasp is a Batesian mimic, as is the tasty butterfly species that wears the colors of an unpalatable one. We had an encounter with what we discovered was a third type here at the office.

“You bug people!” Jean exclaimed. We had just looked at what had to be our 500th “Monarch” butterfly photo, and for perhaps the fourth or fifth time Hank, our editor, and I had said, “That’s a Viceroy,” at exactly the same moment. (We had to agree with her, we are bug people. I even entered my collection at the county fair as a youngster, and Hank, well, I think Hank’s interested in anything even remotely to do with soil [don’t say “dirt”] or growing things.) This led to a discussion of mimicry.

Until relatively recently, Viceroys were the textbook example of Batesian mimicry. Monarch caterpillars spend their leisure time eating milkweed leaves containing a toxic chemical that eventually makes their adult self taste bad. Viceroys look very similar to Monarchs and were thought to be protecting themselves by wearing an unpalatable disguise.