DRAGONFUES AND DAMSELFUES IN PONDFISH CUI.TURE. 249 



mask, and by the absence of dorsal spines along the midline of the abdomen. Their legs 

 are stout and adapted for burrowing, the two front pairs directed forward and the 

 posterior pair directed backward, and all three pairs armed at the tips with strong burrow- 

 ing claws. Their color is similar to that of the debris in which they live, and the furry 

 hairs covering their bodies and legs quickly gather a coating of mud which still further 

 obscures them. When ready to transform they crawl up on some board surface like a float- 

 ing barge, the side of a boat, the bark of a tree, or more commonly a flat mud surface close 

 to the water. In suitable locations the mud will be found thickly incrusted with their 

 nymph skins, and it is not uncommon to find two or more skins one on the top of another, 

 those coming out last crawling up on the others. 



The imagoes scatter quickly as soon as they are able to fly and often entirely disap- 

 pear from the vicinity where they leave their nymph skins. In general, the females 

 retire inland, while the males remain along the water front. 



Their habits are very different from those of the Libellulidse, the imagoes usually 

 alighting flat on the ground or close to it, or on the surface of a log, and squatting or 

 flattening the body down until the wings almost touch the ground, all ready to spring 

 upon their prey. They almost never alight on twigs or grass stems, like the Libellulidae. 

 From this flattened position they dart out over the water, skimming close to the surface 

 and going toward the center of the river or stream, and then return again to the bank. 

 Their motion is more similar to the ordinary aeroplane than that of most Libellulids, and 

 they often hover over one spot for some time. They pluck much of their prey off the 

 surface of the water, and some species actually dive beneath the surface, entirely disap- 

 pearing under the water. 



Although two of the species, externus and vastus, are common about the ponds, they 

 have never yet been observed hunting their prey over the pond surface. They do catch 

 numbers of teneral dragonflies and damselflies, however, in the vegetation around the 

 margins of the ponds. 



The imagoes are so nearly alike in color pattern, wing venation, and even in habits, 

 that it is very difficult for anyone but an expert to distinguish the various species, but 

 the nymphs afford much plainer distinctive characters. 



The pairing of the sexes occurs toward evening, and if one goes out just before 

 sunset there is a good chance of obtaining the two sexes^ together. The male does not 

 accompany the female while ovipositing, and the sexes never fly about together after the 

 manner of some of the Tibellulidse. 



GOMPHUS PLAGIATUS Selys. # 



Gomphus plagiatus Selys, Bull. Acad. Belgique, 1854, vol. 21, p. 57. 



In the Proceedings of the Indiana Academy of Science for 1901, page 123, Williamson said: "The 

 why, whence, and whither of imago Gomphi is a puzzle. " And to no species of the genus apparently 

 does it apply any more forcibly than to the present. The nymph skins of this species were by far the 

 most abundant of any found along the river bank, and over 1,000 were collected during the summer. 

 But the only imagoes caught or seen were two tenerals captured as they were emerging. The imagoes 

 must depart as soon as they can fly at all, and apparently they remain in the place to which they go. 

 Consequently this species can hardly be said to have any part at all in the ecology of the fishponds 

 although such large numbers of them are transformed within a few hundred feet of the ponds. 



Emergence takes place early in the season, usually during the night, so that by the next morning the 

 imago can fly fairly well. 



