AUGUST
2012

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

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Check out these books by Tom Turpin:

Flies in the face of fashion

What's Buggin You Now?

 

 

 

08-23-12

Download the audio of On Six Legs: MP3, WMV

Big Bugs Made of Sticks, Stones and Iron


There's a walking stick found in Southeast Asia that is nearly 2 feet long. The Goliath beetle from Africa weighs about 2.5 ounces. The Atlas moth of the Malay Archipelago has a wingspan of about a foot. These are some of the largest insect species that exist today.

But once upon a time there were larger insects. Back in the day of the dinosaurs there were all kinds of large creatures, including insects. One of the largest insects was a griffinfly. This dragonfly–like insect had a wingspan of 2.5 feet. But like dinosaurs and saber-toothed tigers, this behemoth of an insect has perished, too.

Scientists speculate on why such large insects can no longer be found on the earth. Some say it is because the current oxygen content of the air is not sufficient to sustain insects of that size. Insects depend on diffusion of oxygen to meet their biological requirements. Such a process can only work if the animal is small, and the oxygen concentration of the air is sufficient. So, as the oxygen content of the air declined, large insects were unable to survive.

Another speculation involves the evolution of birds. Many birds are insect predators and as these aerial predators became more adept at flying, they made life miserable for insects. So miserable that birds might have contributed to large-insect species being driven to extinction.

Certainly, today there are no insects the size of cows, but humans have always been fascinated with the "what if" question regarding large insects. We make horror movies with gigantic insects about to wreak havoc on humankind. Recently, a number of traveling exhibits for use in parks and museums featured very large insects.

Butterfly Sculpture
Monarch Butterfly from "Backyard Monsters" exhibit

One of the first of such exhibits is called "Backyard Monsters." This exhibit features six animatronic creatures between 6 and 8 feet tall, 96 times their natural size. The creatures are a tarantula, wasp, two fighting beetles, tomato hornworm caterpillar and monarch butterfly. Advertising for the exhibit promises a bugs-eye view of the world. In other words, how would it be if we were the size of insects and insects were the size of humans?

Praying Mantid sculpture
Sculptor David Rogers with praying mantid

In 1994, sculptor David Rogers created the "Big Bugs" exhibit. Rogers' giant insects are constructed of mature trees, saplings and willow branches. He used red cedar, black walnut and locust. The exhibit includes a bee, spider, dragonfly, ladybug, grasshopper, damselfly, butterfly, praying mantid, assassin bug and several ants. All are large; however one ant is 25 feet long and the praying mantid weighs over 1,000 pounds.

Currently, (through September 2012), the Brookfield Zoo in Chicago is featuring an exhibit called "Xtreme BUGS." The exhibit features 20 giant creatures, including a 33-foot long Japanese hornet and a ladybird beetle the size of a Volkswagen Beetle. These are just two of the metal framework and polyfoam insects, spiders and centipedes in the exhibit.

A couple of years ago, Colombian artist Rafael Gomezbarros created a number of ants - 4 feet in length - and displayed them crawling on the side of a building in Bogota. The artist stated that the giant ants were symbolic of the people displaced by armed conflict in Colombia.

Size-wise, those Columbian ants pale in comparison to the 18-foot ants created by metal sculptor Bill Secunda. One of Secunda's ants is holding a motor scooter in its mouth. In addition to the giant ants, Secunda has created a 14-foot scorpion and a 35-foot diameter spider. He also has fabricated 12-foot steel cockroaches that appropriately adorn a building occupied by a pest control company in Dallas.

Metal ants are one thing, but Italian sculptor Lorenzo Possenti calls his larger-than-life insects "Ecofauna." These sculptures are scientifically accurate in shape and color. According to the sculptor, you can see the intricacies without a microscope. Possenti's Ecofauna insects are about the size of third-graders.

Now that's a scary thought - an insect about the size of and with the attitude of a third-grader. Thank goodness that the oxygen levels of the earth are below that needed for such insects to survive!

 

Writer: Tom Turpin
Editor: Olivia Maddox