PSE UDONE UROPTERA . 



73 



skin of the nymph clinging to the object upon which the transfor- 

 mation took place. Fig. 69 represents such a skin clinging to the 

 stem of a water-plant. 



The dragon-flies are predaceous in the adult as well as in the 

 nymph state ; hence their vigorous flight and strong jaws Tender 

 them formidable foes of less powerful insects. 



It is not strange that there should be many popular superstitions 

 regarding insects so conspicuous as these. It is a common belief 

 among children that they have the power of sewing up the ears of 

 people, hence the name darning-needle ; while the negroes in the 

 Southern States believe that the dragon-flies hover over dead snakes, 

 bringing them to life, and consequently call them snake-doctors. 



The Libellulidae is a remarkably well-defined group of insects. 

 The wings are peculiar in form and venation, and especially in the 

 possession of the nodus ; the reproductive organs of the male are 

 very distinct in form from those of any other insects ; and in the 

 nymph the structure of the mouth-parts and the organs of respira- 

 tion are equally peculiar. Owing to these important differences 

 which exist between the Libellulidas and the most nearly allied in- 

 sects, certain entomologists regard the group as an order, to which 

 they apply the name Odonata. 



FIG. 71. Wing of Dragon-fly, /Eschna. A, arc or arculus; aa, anal angle; ac, antecubital cross- veins; 

 am, accessory membrane or membranule; at, anal triangle; da, basal area or space ; c, c, costal 

 vein ; d, d, d, discoidal areolets ; it, internal triangle ; Is, lower sector of triangle, a prolongation of 

 pco \ 'is', branch of Is ; ni, m, median vein ; ma, median area or space ; ms, ms, median sector j *, 

 nodus : 



postcut 



ss, short sector ';2f,"discofdaT'triangle, usually termed' the tria'ngle ; us, upper sector of the triangle, 

 a prolongation of sttt. 



Figure 71 illustrates the nomenclature of the parts of the wing 

 in insects of this order. 



