114 DRAGONFLIES OF OHIO. 



PACHYDIPLAX, Brauer. 



This genus is represented by a single species. 



The frons above and vertex are metallic blue, which 

 character will separate it from related forms. It flies 

 over shallow water where lilies and other water plants 

 grow, here the female oviposits. Teneral specimens 

 may be found a long distance from water. 



Pachydiplax longipennis, Burm. 



Length: of abdomen c? 20.29, 9 18-24; hind wing 

 c? 25-33, 9 25-31. 



Teneral male, front, labrum and labium yellowish, 

 margins of mouth brown, frons above and vertex 

 metallic blue. Thorax with mid-dorsal carina, an ante- 

 humeral stripe, abbreviated above, an irregular 

 humeral stripe continued above by a transverse stripe 

 before the antealar sinus, a wide, lateral stripe beneath 

 the fore wings, one between the wings and all the post- 

 erior part of metathorax, yellow ; otherwise brown. 

 Legs ; coxae, trochanters and inner side of front tibiae, 

 yellowish; remainder including the feet dark brown. 

 Wings yellowish at base, otherwise hyaline. Abdomen, 

 venter and basal part at sides yellowish, dorsum 

 brownish or blackish usually with a longitudinal row 

 of yellow dashes on 2-8. 



In the fully developed male the abdomen becomes 

 pruinose and all the markings are obscured, the brown 

 of the thorax becomes more or less greenish, and the 

 hind wings have two longitudinal, dark brown, basal 

 streaks, one between subcosta and median veins, the 

 other between submedian and postcostal veins; both 

 reach nearly to arculus. These latter may be present 

 in teneral males. 



The female is colored like the teneral male or pruin- 

 ose in old specimens, her abdomen is widened posteri- 

 orly, her wings are yellowish at extreme base and the 

 hind pair lack the longitudinal stripes. 



Common in all parts of the state. 



