JULY
2005

 

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?

 

 

 

07-28-05

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

Silkworms in America


Silk is a fiber produced by insects and spiders. Spiders use silk to build webs to trap and encase prey and construct homes. Insects use the material to construct safety lines, such as when caterpillars hang from a thread. Insects such as webworms use the silk to build a home. Many immature insects use silk to spin a cocoon in which pupation occurs.

Nearly 5,000 years ago in the Orient, humans discovered that the silk could be unwound from the cocoon of a moth caterpillar now known as the silkworm. Several fibers were then wound into thread for use in fishing lines. Soon the thread was being fashioned into fabric, and the silk industry known as sericulture was born.

Sericulture became such an important industry in the Orient that an attempt was made to prevent silkworms from being taken from that part of the world. However, in 550 A.D. a Monk managed to conceal some silkworm eggs in a cane and smuggle them to Constantinople. As a result, sericulture began in the West.

Production of silk has never caught on in America. But over the years, attempts have been made to create a domestic silk industry. L.O. Howard, a prominent federal entomologist, describes some of the effort in his book, "Fighting the Insects." Howard suggests that the first attempt to raise silkworms in the United States was by colonists in South Carolina.

According to Howard, his predecessor as entomologist in the U.S. Department of Agriculture, C.V. Riley, was interested in silk production. Riley, as state entomologist of Missouri, had selected a strain of silkworm that would feed on the leaves of Osage orange trees. Many Osage orange trees were planted across the Midwest in hedges for use as windbreaks, living fences and posts.

By 1881 Riley had produced a "how-to" manual for raising silkworms and began a federal program to support sericulture in the United States. Under Secretary of Agriculture James Wilson of Iowa there were efforts to develop an efficient method for unreeling the silk from the cocoons and an attempt to establish producer groups.

The plan involved purchasing silkworm eggs from an Italian dealer and distributing them free to anyone who wanted to raise cocoons. A small reeling establishment was set up in Washington to buy the cocoons at standard European prices. The raw silk was to be sold to American manufacturers.

The plan was carried out. But, like many other government programs over the years, did not work out. It failed because of economics -- the silk couldn't be produced for what the government would pay for it!

Silk production has always been a labor-intensive industry, and that certainly worked against the establishment of sericulture in the United States. There were negative things associated with attempts to produce a viable U.S. silk industry. For instance, in 1868 a visiting French astronomer named Trouvelot imported gypsy moths from Europe to use in a proposed crossbreeding program with native silk-producing moths. Some of the gypsy moths escaped from the laboratory in Medford, Mass.; this insect has been moving west and wreaking havoc on hardwood trees ever since.

Years ago, an entomologist at a West Coast university was rearing silkworms. In order to feed his research insects, he was picking the leaves off of the mulberry trees on campus. Voracious eaters that silkworm caterpillars are, they were soon devouring all of the available mulberry foliage on campus. The school administration was not amused at the sight of naked trees. Our erstwhile silkworm entomologist was commanded to cease and desist under penalty of being fired.

What entomologist L.O. Howard said in 1930 relative to sericulture in the United States, "Down to the present time it has not amounted to anything," is still true today. But rearing silkworms is a good educational activity for schools. But a word of warning to teachers: Don't defoliate the mulberry trees to feed a batch of caterpillars. Your administrators just might not understand.

 

 

Writer: Tom Turpin
Editor: Olivia Maddox