DRAGONFUES AND DAMSELFUES IN PONDFISH CULTURE. 



255 



The males frequently come hawking around the laboratory building toward night, alight on the 

 screens, and fly up and down the sides of the building, catching house flies, mayflies, and midges. 

 They also have a curious habit of congregating around straw stacks in the open fields, probably attracted 

 by the insects that frequent the sunny side of the stacks. 



Over the ponds they do not keep to a definite beat or patrol, but wander about indiscriminately, 

 the m.ales frequently clashing with one another. So far as observed, the imagos do not eat other dragon- 

 flies or any of the larger insects. Large numbers of them while teneral fall victims to English sparrows 

 and red-winged blackbirds. 



The nymphs are found in all the ponds, but most plentifully in ponds 3, 4, and 7. These nymphs 

 are always dirty and without a color pattern, but the dorsal hooks on the abdominal segments are 

 always visible. 



Sometimes they crawl long distances from the Vv^ater, but most of the skins were found in the fringe 

 of Carex close to the ponds. A few live in the Mississippi River, and these climb the willow trees 

 on the bank and leave their skins attached to' the bark. 



LIBELLULA PULCHELLA Drury. 



Libellula pulchella Drury, lUust. Exot. Entomol., vol. i, 1773, p. 115. 



Common around all the ponds, but seeming to prefer those nearest the railroad and the ditch along 

 the railroad track. It goes much farther from the water than the preceding species and is often found 

 along the country roads and in the farmyards, industriously hunting the insects which occur there. 

 Nymphs were found in all the ponds, and skins were obtained in every count, but were most abundant 

 the last of July; they are among the largest of the Libellulid nymphs and make excellent fish food. 



PLATHEMIS LYDIA (Drury). 



Libellula lydia Drury, Illust. Exot. Entomol., vol. i, 1773, P- 1^2. 



Like pulchella, this species prefers the ponds and the ditch along the railroad track; the n^^mphs 

 were abundant in the ditch, but rare in the ponds. The male is easily recognized by his white pruinose 

 body and black wings; the female has spotted wings and might be mistaken for pulchella, but is consider- 

 ably smaller, and the triangle of the front wings is entirely free from color. This species is a persistent 

 hunter, and the males have regular beats which they patrol almost constanth''. 



DamsELFLIES. — ^The habits of the various damselflies in ovipositing and the habits 

 and relations of the nymphs to the fish life in the ponds are so similar that a general 

 statement will cover them all, with the exception of a few peculiarities, which may be 

 noted under the separate species. 



When ovipositing, the male grasps the female by the prothorax and flies about 

 with her. She does not dip her abdomen beneath the surface and wash off the eggs 

 after the manner of some dragonflies, but alights on some convenient water plant, 

 floating algae, pond-lily leaf, or rush stem, or upon a floating twig or piece of wood, 

 and places her eggs in position beneath the water, the male retaining his hold and assist- 

 ing her out after she has finished. Often the male holds his body erect in the air, and 

 floating objects are sometimes covered with the females busily ovipositing, while the 

 males stand up from the surface like small twigs or moss stems. In some genera like 

 Lestes, Argia, and Enallagma the female descends into the water and often draws the 

 male in with her. The females of Argia putrida sometimes descend 9 inches beneath 

 the surface, the female clinging to some water plant, the male holding his body erect, 

 with the wings spread. After placing her eggs, the female releases her hold and the two 

 rise to the surface, their buoyancy lifting the male into the air until his wings are free. 

 He immediately begins to fly and lifts the female out of the water, and the two then go 

 to another place and repeat the process. 



