June 24, 2017
Insects and biological classification schemes
Biologists use a hierarchical classification scheme.
Naturally different biologists may champion different schemes
or variations on the following scheme, but we ignore these squabbles.
Note that when talking about plants we use the term "division" rather than "phylum".
The botanists actually cleaned up their nomenclature before the zoologists got around to doing so.
At the top level, all of life is divided into 5 Kingdoms:
- Plantae
- Animalia
- Fungi
- Protista
- Monera (only prokaryotic organisms)
Note that a twofold division of life into eukaryotes and prokaryotes
is interesting, but set aside for our purposes.
A given living thing fits into increasingly specific nested sets.
Here is how it works for a honey bee:
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Hymenoptera
- Family: Apidae
- Genus: Apis
- Species: mellifera
The Arthropoda
Since we are interested in insects, we need to take a close look at the
classes in the Phylum Arthropoda. But before we can do that, we need to
consider three "subphylums":
- Crustacea
- Chelicerata (Arachnida, Merostomata, Pycnogonida)
- Uniramia (Insecta, Chilopoda, Diplopoda)
For our purposes, we will ignore the Crustacea (with its 8 orders).
Spiders are fascinating, but they aren't insects, they are Arachnids,
so we should briefly look at the Chelicerata and then move on.
- Class: Pycnogonida (sea spiders)
- Class: Merostomata (horseshoe crabs)
- Class: Arachnida (4 orders)
The Arachnids have 4 orders, as follows:
- Scorpiones
- Acari (includes mites and chiggers)
- Opiliones (harvestment or daddy-longlegs)
- Araneae (the spiders)
Someday we will take a closer look at the Araneae.
The Uniramia has 3 classes:
- Insecta (many orders)
- Chilopoda (centipedes)
- Diplopoda (millipedes)
The Insecta
More than 70 percent of all named animal species are insects.
Approximately 90,000 described species are found in the United States and Canada,
and there are probably 125,000 species in this area. Here is a list of orders
mentioned in Brusca and Brusca:
- Thysanura (* silverfish, ...)
- Ephemeroptera (mayflies)
- Odonata (dragonflies and damselflies)
- Plecoptera (stoneflies)
- Blattodea (roaches)
- Isoptera (* termites)
- Mantodea (mantids)
- Dermaptera (* earwigs)
- Orthoptera (grasshoppers, crickets)
- Phasmida (stick insects)
- Embioptera (* webspinners)
- Psocoptera (* booklice)
- Phthiraptera (* lice)
- Hemiptera (bugs)
- Thysanoptera (* thrips)
- Coleoptera (beetles)
- Neuroptera (lacewings)
- Mecoptera (* hanging flies)
- Siphonaptera (* fleas)
- Diptera (flies)
- Trichoptera (caddisflies)
- Lepidoptera (butterflies, moths)
- Hymenoptera (wasps, bees, ants)
- Strepsiptera (* twisted wing parasites)
- Archeognatha (* jumping bristletails)
- Notoptera (** includes Mantophasmatodea and Grylloblatodea)
- Megaloptera (** alderflies, was in neuroptera)
- Raphidioptera (** snakeflies, was in neuroptera)
- Zoraptera (** angel insects, 39 species)
In the above, a pair of asterisks indicates recent regrouping.
A single asterisk indicates an "oddball" order (but aren't all insects odd?).
One out of every four animals is a beetle.
There are over 24,000 species in North America north of Mexico.
Have any comments? Questions?
Drop me a line!
Tom's Insect pages / tom@mmto.org