Name
Enrichment
Redi’s Experiment
Francesco Redi was born in Italy in 1626. At
age 21, he received a medical degree from the
University of Pisa, Italy. From then on, he
worked as a doctor.
Most of the people of Redi’s time thought
living things came spontaneously from mud
or decaying meat. A few scientists, including
Redi, thought that idea was probably not true.
He decided to try to find out how maggots
appeared in decaying meat. Many thought the
maggots came from the meat, but Redi
thought that flies laid their eggs on the meat
and the maggots hatched from those eggs.
To test his theory, Redi prepared eight containers. Into each he placed a piece of meat or
fish. He then sealed four of the containers and
left four uncovered. Drawn by the smell of the
meat, flies buzzed around the containers. After a
few days, maggots appeared on the meat in the
four uncovered containers. The meat in the four
covered containers had decayed, but there were
no maggots.
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Class
Next, Redi prepared eight more containers
for a second experiment. Into each, he placed a
piece of meat or fish. He then covered four of
the containers with gauze, which allowed air to
move freely in and out of the containers. He
again left four containers uncovered. As before,
flies buzzed around the containers, attracted by
the smell of the meat. After a few days the
results were the same—maggots could be found
only on the meat in the uncovered containers.
1. Before the 1700s, some people believed that life came from mud or decaying meat. What is this
theory called?
2. What theory did Redi prove?
3. In the first experiment, what did Redi prove?
4. What did Redi do differently in the second experiment?
5. What did Redi prove in the second experiment that he had not already proved in the first?
Exploring and Classifying Life
31
Meeting Individual Needs
3
Date
Name
4
Date
Enrichment
Class
A bug or a beetle?
Often we pick up an insect and casually refer to it as a bug or a beetle. Using scientific definitions, the insect may not belong to either of these orders of insects. Bugs belong to the order
Hemiptera and beetles belong to the order Coleoptera. Look carefully at these two pictures and
use the key below to find out which order these insects belong to. The key is not complete for all
orders of insects, but it should help you tell the difference between bugs and beetles. There are a
few wingless bugs that are not covered by this key. Use other references if needed.
Head showing
beak
B.
A.
Key (partial) to Orders of Insects
1. Wing type
a. wings transparent, go to 2
b. front wings hard or leathery and covering hind wings, go to 2
2. Type of mouthparts
a. mouthparts chewing, go to 3
b. no chewing mouthparts, go to 4
3. Wing venation
a. front wings with veins, Orthoptera
b. front wings without veins, Coleoptera
4. Front wing texture
a. front wings nearly always thickened at the base; membranous at tip, beak comes from front or bottom of head;
antennae have 4 or 5 segments, Hemiptera
b. front wings of uniform texture; beak comes from hind part of head, Hemiptera
1. Which insect is a true bug and which is a true beetle?
2. What are some of the distinguishing characteristics of the insects shown? List them below.
Bug
Order
Wings
Antennae
Mouthparts
32 Exploring and Classifying Life
Beetle
Copyright © Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.
Meeting Individual Needs
Front wing