JUNE
2004

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

06-24-04

Flea Glass Apt Name for a Microscope

An unknown entomologist once stated that insects are big enough to see, but not big enough to see well. That comment speaks volumes about human-insect interaction. When it comes to insects, what we can't see, we imagine!

The human imagination sometimes runs wild when it comes to insects. Take for instance, that human psychological condition known as delusory parasitosis. People suffering from this disorder believe they have microscopic creatures living on them. But they don't; they just imagine that they do. It has to do with the small size of insects, such as fleas and lice. 

That brings us to the development of the microscope and how that device showed insects in a new light. Galileo is known for his work with the telescope, but when he looked through the other end of the device he had a microscope. While he was not a biologist, the earliest biological observation with a microscope is credited to Galileo. He is said to have reported that each eye of a small animal is "perforated with holes to afford passage to the images of visible things." Galileo was describing the compound eye of an insect.

The earliest published figures prepared with the aid of a microscope are credited to Francesco Stelluti, who in 1630 wrote, "I have used the microscope to examine bees and all their parts."

Stelluti also noted, maybe bragged is a more appropriate term, that he had prepared figures of other insects that were unknown to Aristotle! Aristotle, maybe the greatest biologist who ever lived, didn't have the use of the microscope. So, he can be excused for overlooking a few small insects.

In the early days of its use, the microscope was called a flea glass -- a descriptive term, for sure. The name probably originated from the work of the classical microscopists, including Antony van Leeuwenhoek. In 1693, Leeuwenhoek described the metamorphosis of the flea. He drew detailed pictures of egg, larvae, pupa and adult. He even described a minute mite parasite on the larva. This observation probably gave rise to the Johathan Swift lines:

            "So naturalists observe, a flea

            Has smaller fleas that on him prey;

            And these have smaller still to bite 'em;

            And so proceed ad infinitum."

Another microscopist, Robert Hooke, also looked at minute insects, spiders and mites. He drew the flea in great detail and large size. His pictures were unsurpassed for accuracy for nearly a century.

The flea glasses of more than 300 years ago allowed observers to look at insects more closely than ever before. The new-found tool allowed those who took an up close and personal look at insects to discover all kinds of things. For instance, some aphids, when dissected, had little aphids inside, supporting the idea that aphids sometimes gave birth to live young.

The insides of insects were no longer secret, and the early scientists had their first close up look at the internal workings of insects. It was discovered that the holes on the sides of insects were attached to tubes, forming the breathing system.

The microscope has allowed scientists to clearly look at very small insects. But some people prefer not to see the teeth on a flea. They would just as soon not know that much about something that will take a bite when it gets the chance.

 

Writer: Tom Turpin
Editor: Olivia Maddox