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How to Identify Insects to Order
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Part of making an insect collection is learning how to correctly classify the specimens. This is a very challenging assignment, because there are so many insects and so many of them look alike. Do not be discouraged if there are specimens that cannot be identified. Remember that even professional insect taxonomists (entomologists who identify and classify insects) cannot identify every species of insect. Some must specialize in working with one group and others with another group.

Classification, the grouping and naming of insects, is an ever-changing science. Insect specialists separate and combine groups of insects based largely upon their morphological similarities, some having more influence in a decision than others. As such, this process is somewhat subjective and, thus, dynamic. A student of entomology may find slight differences in classification schemes depending upon which reference or which entomologist they consult, and these may change over time.

Not all orders of insects are the same size. For example, more than one-third of the named species of insects (300,000) are in one single order, the Coleoptera (beetles). The next largest orders are Lepidoptera (butterflies and moths), with 150,000 species; and Hymenoptera (wasps and bees), with 125,000 species. The order Diptera (flies) includes about 20,000 species. These four orders, Coleoptera, Lepidoptera, Hymenoptera, and Diptera, comprise more than 80 percent of the named species of insects.

Approximately 92,000 named species of insects occur in the United States and Canada. It is not known how many of these species occur in any one state or in even a small area within a state. A list of insects in New York, published in 1928, included more than 15,000 species, but hundreds of species have been discovered there since that time. States such as California, Arizona, Texas, and Florida probably far exceed the Midwest and Northern states in the total number of species of insects.

Estimates of the number of species for three representative states and also for all of USA and Canada are provided as an indication of the number of species that insect collectors may expect to find (Table 1). A collector who can find one or more representatives of each of the 24 orders discussed in this book will have a very diverse collection, and in so doing will learn a great deal about insects and their habits.

Table 1. Estimated Number of Species
Order North Carolina New York Indiana USA & Canada World Wide
Collembola 169 200 200 314 9000
Thysanura 6 5 7 25 900
Ephemeroptera 121 61 120 690 3100
Odonata 148 159 150 425 5500
Dictyoptera 23 15 20 101 5800
Orthoptera 235 121 150 925 20000
Dermaptera 7 4 5 18 2000
Isoptera 5 1 5 41 2900
Plecoptera 94 59 85 408 2000
Psocoptera 37 38 30 150 4400
Mallophaga 164 53 90 318 4000
Anoplura 11 11 15 62 900
Thysanoptera 64 71 150 600 5000
Hemiptera 568 727 800 4600 40000
Homoptera 759 864 900 6700 50000
Neuroptera 68 61 65 338 6500
Megaloptera 9 10 15 61 300
Coleoptera 3336 4546 4424 30000 350000
Mecoptera 27 20 20 89 600
Trichoptera 161 174 210 980 11000
Lepidoptera 1428 2439 2000 10100 150000
Diptera 2595 3615 3600 17000 120000
Siphonaptera 14 26 28 250 2500
Hymenoptera 2463 2300 2800 17000 125000