Identifier: annualreportofbo1929smit (find matches)
Title: Annual report of the Board of Regents of the Smithsonian Institution
Year: 1846 (1840s)
Authors: Smithsonian Institution. Board of Regents United States National Museum. Report of the U.S. National Museum Smithsonian Institution. Report of the Secretary
Subjects: Smithsonian Institution Smithsonian Institution. Archives Discoveries in science
Publisher: Washington : Smithsonian Institution
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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tion through a thoracicsegment of a hypothetical insect with paranotal, or glider, lobes inplace of wings. DMcl, Dorsal longitudinal, intersegmental muscles;L, base of leg; Pi, pleuron; pnl, paranotal lobe; S, sternum 390 ANNUAL REPORT SMITHSONIAN INSTITUTION, 192 9 rarious forms that appear to be representative of several othermodern orders of wing-folding insects. The roaches at least wereinhabitants of the forests, adapted to living in the matted vegeta-tional debris of the forest floor, on the scaly-barked trees, or betweenthe bases of their frondlike leaves. The dragon flies belong to the order Odonata, but there are twodistinct suborders of them. One suborder, known as the Anisoptera,includes the ordinary large species, or true dragon flies (fig. 7), which,when at rest, keep the wings spread straight out at the sides of the body.The other suborder is the Zygoptera and includes species generallysmaller in size which, when at rest, fold the wings over the back with #^^^-^,.-. ,.jg
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Figure 7.—Dragon flies of the suborder Anisoptera. When the insects are perched the wings areheld horizontally at right angles to the body the dorsal surfaces together. (Fig. 8.) Members of the Zygopteraare sometimes distinguished as damsel flies; most of them are ratherweak creatures with long, slim abdomens and slender wings narrowedat the bases. They are comparatively feeble fliers and are easilycaught. The true dragon flies of the suborder Anisoptera are sub-divided into two families, the Libellulidae and the Aeschnidae. Thelibellulids are the common dragon flies seen about streams and pools,where they perch on the ends of twigs from which they dart out onvigorous short flights in pursuit of some small passing insect. Theaeschnids include those large species that we used to call Devilsdarning needles. Thej^ are most efficient fliers, being seldom seen to.alight anywhere as they go skimming above the surface of the water. HOW INSECTS FLY SNODGTIASS 391

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