Unit 3 of Entomology
Unit 3: Insect Orders.
Now that you’ve taken a look at how things are classified, and how insects evolved, we’re going to take
a look at some of the more common insect orders. After you’ve completed this unit, you should know, for
each insect order, the common name, order name, a meaning of the order name, the development and
metamorphosis of that type of insect, three to four facts regarding its life history and/or economic
importance. You should also know the wing type, leg types, and mouth adaptations for specific insect
Just as a thought question, how do you tell the difference between a bee and a beetle?
The answer to this question may seem easy, but when you really think about it, it is a challenge to
describe the difference to another person. They both have wings, six legs, and antennae. You can’t just
say, “Well, that one looks like a bee and that one looks like a beetle.” There’s more to it than that. By the
end of this unit, you should be able to tell someone, without hesitation, the difference between these two
insects as well as many others. As you progress through the unit, you’ll refer to the textbook for
information to fill in your study guide table. The textbook has an appendix dedicated to describing the
insect orders, but more detailed descriptions are scattered in textboxes throughout chapters 7 through
You should recall from the first unit how organisms are classified. An organism is first classified into the
kingdom, then phylum, class, order, family, and lastly, genus and species. You’ve already learned that
insects are in the kingdom Animalia, and in the phylum Arthropoda, along with lobsters, spiders, and
crabs. You also know that insects are in a separate class called Insecta. The class Insecta is then
broken down into 26 insect orders, and these orders are then separated into families. For example: a
scarab beetle is in the class Insecta, the order Coleoptera, and the family Scarabaeidae. A bee is in the
class Insecta, the order Hymenoptera, and the family Apidae. The lineage is diagramed on the next
Here you see, as we go down from class Insecta to order, the orders are split into Hymenoptera and
Coleoptera, and then the two separate families, Apidae and Scarabaeidae.
As I said before, this unit will familiarize you with some of the major insect orders. But before you get
started, see how many of the following terms you know by writing their definitions on a piece of paper.
These terms will help you throughout the unit and on your lab projects.
OK, here’s a list of those terms and their definitions. You have anamorphic, ametabolous,
hemimetabolous, and holometabolous. We’ve already discussed a bit about the types of
metamorphosis, but here you have the definitions. Continue on to the next slide for some more