70 AN INTRODUCTION TO ENTOMOLOGY. 



Family II. LIBELLULIDAE.* 

 Order ODOXATA 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. 67). 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 



^.^-Plathentistrimaculata. (From Sanborn.) 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 



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

 during flight. 



\ OdonSta: odous (o5ot>?), a tooth. 



