SEPTEMBER
2009

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

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09-24-09

Download the audio of On Six Legs: MP3, WMV.

Pretty in Pink Katydids, Oh My!

Katydids are fairly well known insects. As insects go, katydids are large and they sing. In fact, most of us hear katydids more often than we see them. The insect gets its common name from the sound it makes. It is easy to imagine that the insect is saying, "katy did" or katy didn't," or even, "katy did she did."

We don't see the insect often because it generally lives in treetops and is protectively colored. Katydids are green and somewhat leaf-shaped. The color and shape allow katydids to blend in nicely with the environment in which they live. One of the risks in life for a katydid, like a lot of insects, is becoming a meal for some insect-eating predator. So camouflage is an oft-used insect-survival mechanism.

But every so often a katydid with a very unusual color shows up. A pink katydid! A katydid of that color was recorded in a scientific article in 1887. Since then, it has been estimated that pink katydids are rare -- occurring in one of about 500 individuals.

Pink is an unusual color in any type of animal. To be sure, there are pink-skinned animals, including some pigs, rats and mice. And there are albino animals of all types that have pink eyes as well as skin. Probably the most widely recognized pink animal is a bird -- the pink flamingo. These long-legged wading birds acquire their pink color from food. The pink flamingoes eat brine shrimp, which provide the beta-carotene responsible for the pink color of the birds.

So what is the deal with the rare pink katydids? The condition is called erythrism and shows up in the oblong-wing katydids from time to time. It apparently is similar to the situation in albino animals where the condition is due to recessive genes. When the correct combination of recessive genes is present, the condition is expressed as an albino animal. The same apparently is true of pink katydids, although very little scientific data exist.

In the past, people have tried to produce pink katydids in captive breeding experiments, but with limited success. However, last year the New Orleans Audubon Insectarium acquired a pink male and a pink female katydid; researchers there were able to produce a brood of pink katydids. Those katydids are now on display at the insectarium.

It would seem that a pink katydid is at a disadvantage when it comes to survival in the real world. The pink individuals stand out like "a sore thumb" on the green plants where katydids live. This means that pink katydids are more likely to become a meal for an insect eater than individuals that are green. So being pink might not be good for a katydid, unless you happen to be lucky enough to live at the Audubon Zoo!

Maybe the pink color of katydids is an experiment of Mother Nature. It could be a test of gene combinations that might turn out to be successful. In at least one other type of insect with predominantly green colors, a pink form has worked out.

This insect is called the African flower mantid, and it uses its pink color as camouflage while it hides in pink flowers waiting for prey insects to land. While in pink flowers, the mantid is not as visible to its potential predators. So, in this instance, being pink benefits the mantid in two ways. However, for the color to be beneficial the insect must hang around on pink flowers, a behavioral adaptation to making the color work for it.

Many insects use bright colors, primarily red and orange, as warning coloration. Such colors send a message that the insect is bad tasting or potentially harmful to creatures that see it. A few insects employ such colors even if they are not harmful but gain protection by mimicking creatures of similar color that are harmful.

So will pink katydids some day be common because they have a bad taste or feed on pink flowers? Or are these insects just a relic of the past like the human appendix? No one knows for sure. For now, though, a katydid is certainly pretty in pink. And they make a great display at a zoo.

 

Writer: Tom Turpin
Editor: Olivia Maddox