FAMILY LIBELLULIDy^ 



This is one of the largest dragon-fly groups in the United 

 States, and comprises some of the most beautiful species. With 

 many forms the wings are beautifully banded with brown, either 

 in a series of cross bands or with large blotches which sometimes 

 cover the basal half of the wings. The abdomens of some 

 species are covered with a whitish powder-like substance which 

 is not seen when the insects first emerge from the nymph, but 

 which, when they grow old is sometimes so abundant as to make 

 the abdomen appear perfectly white. A characteristic feature of 

 these forms, especially those of the typical genus Libellula is 

 that the abdomen assumes the shape of a prism, with a strong 

 sharp longitudinal ridge above the flat sides and a flat underside, 

 in some forms the wing markings are not dull brown, but 

 become yellowish and in the very handsome and common 

 Libellula ptilchella, of Drury, the brown spots alternate with 

 milk-white spots. They are very abundant about stagnant ponds 

 and such pools as harbor water-lilies and rushes. They are 

 favorite food of the king bird. 



The females poise themselves close to the surface of the 

 water, remaining almost motionless and striking the water with 

 the tip of the abdomen in the act of laying their eggs. 



With the exception of the Agrionidae these are the most 

 numerous dragon-flies in this country. 



Needham says that the nymphs are sprawlers upon the 

 bottom, mainly in shallow water, or clamber over fallen plant 

 stems, and are protectively colored. 



A single egg-mass of one of these dragon-flies has been 

 observed by Needham to contain 1 10,000 eggs. 



Williamson has shown that one of the species has the habit 

 of resting on the top of a rush, each one being, apparently, 

 proprietor of a certain territory. When another one encroaches, 

 "he is quickly hustled away by the rightful and irate owner." 



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