ODONATA 



315 



Fig. 359- —A damsel-fly. 



three large lobes, which with the labnim 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 

 costal border of each is divided into basal 

 and apical parts by what is termed the nodus 

 (Fig. 364, n). The legs are rarely used for 

 walking, but are used chiefly for perching, 

 and are set far forward ; the tarsi are three- 

 jointed. The abdomen is long, slender, and 

 more or less cylindrical; the caudal end is 

 fiunished with clasping organs in the males. 



A remarkable peculiarity of the order is 

 the fact that the copulatory organs of the 

 male are distinct from the opening of the 

 vasa deferentia ; the former are situated on 

 the second abdominal segment, the latter on 

 the ninth. Before pairing, the male conveys 

 the seminal fluid to a bladder-like cavity on 

 the second abdominal segment ; this is done 

 by bending the tip of the abdomen forward. 

 Except in the subfamily Gomphinae, the pair- 

 ing takes place during flight. The male 

 seizes the prothorax or hind part of the head 

 of the female with his anal clasping organs; 



the female then curves the end of the abdomen to the organs on the 

 second abdominal segment of the male. Pairs of dragon-flies thus 

 united and flying over water are a common sight. 



The Odonata are predacious, both in the immature instars and 

 as adults. The adults feed on a great variety of insects, which they 

 capture by flight; and the larger dragon -flies habitually eat the 

 smaller ones, but a large part of their food consists of mosquitoes 

 and other small Diptera. 



The eggs are laid in or near water. All of the damsel-flies and 

 many dragon-flies are provided with an ovipositor, by means of 

 which punctures are made in the stems of aquatic plants, in logs, in 

 wet mud, etc., for the reception of the eggs. The females of those 

 dragon-flies that lack a well-developed ovipositor deposit their eggs 

 in various ways. In some species the female flies back and forth 

 over the surface of the water, sweeping down at intervals to touch it 

 with the tip of her abdomen and thus wash off one or more eggs into 

 it. In other species the eggs are laid in a mass on some object just 

 below the surface of the water; some species do this by alighting 

 upon a water-plant, and, pushing the end of the abdomen below the 

 surface of the water, glue a bunch of eggs to the submerged stem or 

 leaf; in other species the mass of eggs is built up gradually; the 

 female w411 poise in the air a short distance above the point where the 

 mass of eggs is being laid, and at frequent intervals descend with a 

 swift curv^ed motion and add to the egg-mass and then return to her 

 former position to repeat the operation. Still other species hang their 



