APRIL
1999

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

04-08-99

Many Immigrant Insects Become Pests in a New Land

The balance of nature is a fragile thing. Philosophers, poets, ecologists and even advertising writers often warn us not to fool with Mother Nature. Barry Commoner, in one of his rules of ecology, put it this way: “Mother Nature knows best!”

Indeed, life on this earth is an intertwined web of endless connections. From the most complex life forms to the simplest, everything has its place. Only the human, of all animals, has the ability to willfully change the shape of things on this earth.

One of the ways we humans have created change is by moving things around. We love to give Mother Nature a hand. We carry our favorite plants and animals with us wherever we go. Sometimes, we even unintentionally provide transportation to some of nature's creatures.

Insects, it seems, have been more than happy to hitchhike around the world, compliments of humans. Take cockroaches for example. These insects are native to tropical regions of Africa, but many species have managed to stowaway with human travelers to most parts of the world.

Many insects arrive on distant shores out of sight of their human transporters. For instance, the Hessian fly, that nasty little pest of wheat, came to the United States in straw. The straw was the stuffing for mattresses used by Hessian soldiers who fought in the Revolutionary War.

Broomcorn was the source of the first European corn borers to cross the Atlantic. Our most recent widely publicized invader, the Asian long-horned beetle, was nestled in crating made from infested timber. The crates and the insect ended up in Chicago and New York.

Root stocks for nursery plants imported into this country in 1916 carried grubs. These grubs were Japanese beetle grubs, and the insect has been following the advice of New York publisher Horace Greeley ever since—Go West! Japanese beetles also have taken advantage of air travel prior to the advent of frequent flyer miles and via airplanes have managed to arrive in several airports, including Chicago and Cincinnati.

Some well-known immigrant insect pests were intentionally brought to our shores. The gypsy moth, that ravenous chomper of tree foliage that is munching its way from the East Coast, was part of an experiment to improve silk production in this country. A French astronomer brought the insects to his laboratory in Medford, Mass., intent on crossing them with native silkworm moths. The experiment didn't work. The gypsy moths escaped from the research enclosures and the rest, as they say, is history!

It is a similar story with the African honey bees. That strain was introduced into Brazil to improve the native bees in that country. Play it again, Sam! The bees managed to escape the enclosures, which were provided by the researcher, and have been moving northward ever since.

Sometimes, an insect we intentionally introduce can end up as a pest. The Asian ladybug is an example. It was introduced as a biocontrol agent by the U.S. government. The ladybug is a predator on aphids; that is good since we don't like aphids feeding on our plants. But, its habit of overwintering in great numbers in our homes has become a problem.

None of this is a surprise to entomologists, who long ago recognized that insects established outside their original habitats could become a problem. Why? Because in Mother Nature's order of things, there are checks and balances to everything. In areas where those checks and balances do not exist, the insect population gets out of control.

Once again, we are reminded about nature by the saying, that when “Mamma's not happy, nobody's happy!”

 

Writer: Tom Turpin
Editor: Olivia Maddox