248 



BUI.I.ETIN OI^ THE BUREAU OI^ FISHERIES. 



the other pair free, she will deposit her eggs freely in any convenient receptacle if the 

 tip of her abdomen be dipped in water. Thousands of eggs can be obtained in this way 

 in a short time and kept until they hatch, or they can be placed at once in the breeding 

 pond. The eggs of Anax, i^schna, and the damselflies can be secured by watching the 

 females while ovipositing and then transferring the leaves or stems containing the eggs 

 to the breeding pond. 



11. If there is any necessity for rearmg the nymphs before placing them in the 

 breeding pond, they can be fed on Paramoecium obtained by making an infusion of ma- 

 nure in water, or on ordinary tow, especially the small Crustacea, which they will devour 

 in large numbers. Warren carried dragonfly nymphs successfully through their entire 

 life history by feeding them with mosquito larvae and pupae. 



12. Whenever a fishpond is drained, the nymphs in it should be saved; they make 

 excellent food for fish in other ponds and can be fed to them or can be used to restock 

 the drained pond when it is filled again. 



13. Dragonfly eggs hatch in 8 to 12 days; the nympn is short and thickset, the thorax 

 and abdomen about as wide as the head, the legs long and slender, the antennae short and 

 fairly stout, the eyes large, with black retinal spots surrounded by rings of colored pig- 

 ment. The mentum of the mask is much wider than long, with three mental setae on 

 either side and a varying number of lateral and marginal setae. The lateral lobes have a 

 terminal, movable hook, one raptorial seta, marginal setae on the outer margin, and usu- 

 ally two small setae on the blade of the lobe. The respiratory tracheae are convoluted 

 in the thorax and posterior abdomen and comparatively straight between the two, and 

 are highly colored. 



14. Damselfly eggs hatch in about three weeks; the nymph is long and slender, the 

 thorax and abdomen considerably narrower than the head; the legs relatively short and 

 slender; the antennae stout and long; the eyes small with few retinal spots, but each sur- 

 rounded by colored pigment. The mentum is somewhat wider than long, with a single 

 mental seta on either side and one or two lateral and marginal setae. The lateral lobes have 

 a stout, terminal, movable hook and one raptorial seta. The respiratory tracheae are 

 highly colored and are convoluted in the thorax and anterior abdomen and are compara- 

 tively straight posteriorly. The caudal gills are cylindrical, very long and slender, and 

 taper regularly from the base to the tip. 



ANNOTATED LIST OF DRAGONFLIES AND DAMSELFLIES OBTAINED 

 NEAR FAIRPORT, IOWA. 



The Genus Gomphus. — ^The nymphs of this genus live in the mud or sand on the 

 bottom of the Mississippi and its tributaries, and thus far none of them has been found 

 in any of the fishponds. There is no reason, however, vv^hy pond species like graslinellus 

 and suhmedianus should not be found there, as they probably will be in the future. 

 They burrow into the mud and debris, leaving only the tip of the abdomen exposed for 

 respiration, and lie in wait for their prey. They are both rapacious and omnivorous 

 and will eat anything and everything small enough to be caught and held by their power- 

 ful jaws. They may be recognized by their thick and hairy, four-jointed antennae, which are 

 usually inclined inward toward each other, by a flat labium simply folded beneath the 

 chin, with strong grasping arms like mandibles and not extending up over the face in a 



