70 



AN INTRODUCTION TO ENTOMOLOGY. 



Family II. — LlBELLULlD^E.* 

 Order ODONATA f of some authors. 

 {Dragon-flies.) 

 The Dragon-flies are very common insects in the vicinity of 

 streams, ponds, and lakes. Many of them are of large size ; and, as 

 they fly vigorously during the day-time, they are well known. They 

 have consequently received a number of popular names. The most 

 common of these used in this country are Dragon-flies, Darning- 

 needles, Spindles, and Snake-doctors. 



The form of members of the Libellulidae is very characteristic 

 (Fig. 6y). The most striking features are the long, spindle-shaped 



body, and the long, nar- 

 row, powerful wings ; of 

 which the second pair 

 are as large as or larger 

 than the first pair. 



The head of a dragon- 

 fly is large, broad, often 

 semi-globose, and con- 

 cave behind. A con- 

 siderable part of its sur- 

 face is occupied by the 

 enormously developed 

 compound eyes. The 

 antennae are short ; 

 they consist of from five to eight segments ; of these the two basal 

 ones are thick, the others form a bristle-like organ. The mouth- 

 parts are well developed. The labrum is prominent; the mandibles 

 and maxillae are both strongly toothed ; and the labium consists of 

 three large lobes, which with the labrum nearly enclose the jaws 

 when at rest. The thorax is large. The wings are, as a rule, of 

 nearly similar size and structure; they are richly netted with veins; 

 and the front border of each is divided into basal and apical parts 

 by what is termed the nodus {n, Fig. 71). The veins and cells are 

 much used in classification ; the terms applied to them are given in 

 the explanation of Fig. 71. The abdomen is long, slender, and 

 more or less nearly cylindrical ; the caudal end is furnished with 



Fig. 67. — Plathemis trimaculata. (From Sanborn.) 



* Libellulidae, Libellula: libella, a water-level, on account of the position of the wings 

 during flight. 



f Odonata: odons (oSovS), a tooth. 



