JULY
2002

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

7-25-02

Insect Hitchhikers See the World, Complements of Humans


Many pest insects, it seems, have responded to human marketing slogans for travel. "See the USA in your Chevrolet," "Fly the Friendly Skies" and "Ride the Rails" could apply to insects as well as humans.

Insects are pretty good at locomotion under their own power. They are masters at running, jumping and flying. But, in spite of their natural talent for movement, insects also hitch rides on planes, cars, trains and boats.

Many times, when these insect hitchhikers make their way into new areas, they become pests. In fact, insects that originated in foreign lands account for more than half of the major insect pests in the United States. These are known as exotic pests.

Insects are not the only exotic pests. All kinds of foreign animals, including birds, rodents, snakes and fish, have become pests. The same is true of plants. Ecologists are not surprised when foreign plants and animals become pests in a new habitat. Once outside their native areas, their populations are not controlled by predators and parasites and end up reaching high numbers.

So how do these exotic pests arrive on our shores? In some instances, they were intentionally "imported." But in most situations, the insect was accidentally introduced.

A French astronomer, who was working on the East Coast at the time, imported gypsy moths. He was intent on cross breeding the species with some of the native silk-producing moths to create an American silkworm. Some gypsy moths apparently escaped from their cage in Medford, Mass., around 1869. The insect feeds on trees in the larval stage. It has become a major pest of trees in the United States.

The gypsy moth is moving westward, primarily as a result of female moths attaching egg masses to vehicles in campgrounds. When the vehicle leaves the campground and moves to another location, the egg mass rides along. If the egg masses hatch in a location that was previously not infested and the young larvae survive, the gypsy moth population has expanded its range.

Other exotic pests include the European corn borer. This corn pest was probably introduced into the country in shipments of broomcorn from Italy or Hungary about 1910. For sure, the corn borer was present in 1917. By the 1950s, it was present in most of the major corn production states.

About the same time as the corn borers, Japanese beetles graced our shores from Europe. These insects arrived as grubs associated with rootstock imported from Japan, hence the name Japanese beetle. Now, the insect is chowing down on more than 350 plants in all of the states east of the Mississippi River and has become the nemesis of gardeners everywhere. After airplane travel began, Japanese beetles started traveling via aircraft!

The Hessian fly, a major pest of wheat, arrived during the Revolutionary War. It was a stowaway in the straw bedding used by the Hessian troops, who were here to do battle with the colonists. The first report of the Hessian fly was from Long Island in 1779.

Recently, the Asian long-horned beetle appeared in Chicago and New York. The insect feeds in the wood of trees as an immature. Asian long-horned beetles arrived aboard ships, hidden in the wood where they had been feeding.

Insects have been hitching rides on human conveyances forever. It is a fast way to travel, but, like any hitchhiker, they never know where they will be dropped off!

 

Writer: Tom Turpin
Editor: Olivia Maddox