CHAPTER 4 



Odonata 



By Ray F. Smith and A. Earl Pritchard 

 University of California, Berkeley 



The dragonflies and damselflies are usually the most 

 conspicuous insect group near any body of inland 

 water. Their beauty and wonderful powers of flight 

 attract the attention of all. The order is distinguished 

 from other insects by having two subequal pairs of 

 net-veined wings, three- segmented tarsi, short setiform 

 antennae, strong chewing mouth parts, and large 

 compound eyes. 



The large size of some dragonflies (our largest has 

 a wing spread of about five inches) and their activi- 

 ties have given rise to a large number of superstitions. 

 This is reflected in common names such as "devil's 

 darning needle," "snake feeder," ''snake doctor," 

 and "horse stinger." They, of course, do not sting, 

 but the larger forms can give a small, harmless bite. 

 The common name "mosquito hawk" refers to their 

 value in destroying mosquitoes, gnats, and other 

 pests. On the other side of the ledger certain forms 



are pests about bee yards, and some of the larger 

 naiads occasionally take trout fry. On the whole, 

 however, they are a very beneficial and attractive 

 group of insects. 



The damselflies (members of the suborder Zygoptera) 

 hold the wings together above the body or tilted up- 

 ward when at rest. They also have narrowly transverse 

 heads with eyes separated by more than their own 

 width. The dragonflies (members of the suborder 

 Anisoptera) hold the wings horizontally in repose, 

 sometimes tilted up or down, and the eyes are never 

 separated by more than their own width. 



The dragonflies and damselflies are handsomely 

 constructed. In certain features they are unique among 

 the insects. It is not possible to cover this subject 

 here (for details see Tillyard, 1917; Needham and 

 Heywood, 1929; Walker, 1953; and Needham and 

 Westfall, 1955). Special attention should be drawn 



Middorsal 



thoracic 



carina 



ante-alar 

 crest •- 



fore 



middle 



and hind tarsi 



genital 

 pocket 



Fig. 4:1. Head (dorsal view) and thorax (lateral view) of 

 Aohylla protracta (Needham and Westfall, 1955). 



106 



