236 



BUI.LETIN OF THE BUREAU OF FISHERIES. 



everything being left undisturbed. The upper portion of the cage was covered with 

 chicken wire whose meshes were large enough to allow free access to the insects upon 

 which the dragonflies usually fed. But as soon as the dragonfiies found they were shut in, 

 they would neither alight on the water plants, nor touch the insects that flew through the 

 cage, nor mate, nor oviposit. Instead, they spent their time beating their wings against 

 the sides and top of the cage until they became exhausted and fell into the water, or were 

 picked out through the meshes of the wire by red-winged blackbirds, which were 

 attracted by the beating of the insects' wings. 



While the dragonflies are thus averse to breeding in confinement the damselfiies 

 take kindly to it, and Balfour-Browne (1909) succeeded in obtaining a large number of 

 eggs from specimens of two English species, Agrion pulchellum and Ischnura elegans, 

 which he kept for a week in a cage. He fed the captives on flies and other insects cap- 

 tured in a sweeping net and placed ^live in the cage. The eggs hatched into nymphs 

 in about three weeks, so that he was able to determine definitely the period of incubation 

 for these species. This method was not tried on our American damselfiies, but there is 

 little doubt that it would work as well with them as with the English species. It was 

 found absolutely necessary to keep the cage in the bright sunlight, because in the shade 

 and on dull days the damselfiies became torpid and simply clung to the sides of the cage. 

 It is evident, therefore, that nothing can be accomplished by endeavoring to breed dragon- 

 flies in this manner ; their natural habits and instincts are against it. And although the 

 damselfiies are more susceptible to captivity, this artificial breeding is a rather laborious 

 process for any except the scientific expert who wishes to absolutely isolate a given 

 species. 



Fortunately there are other ways of accomplishing the desired results, and these 

 prove to be highly successful. As already stated, many female dragonfiies deposit 

 their eggs loosely in the water or upon the floating algge by hovering close to the surface 

 and touching the water at intervals with the tip of the abdomen. If such a female be 

 caught as she comes down to the pond to lay her eggs or while she is ovipositing and one 

 pair of wings be folded together over the back and held between the thumb and fore- 

 finger, leaving the other pair free, she will continue to lay eggs in large numbers if the 

 tip of her abdomen be dipped in water in a convenient tumbler, basin, or small jar. 

 Tillyard (191 7, p. 358) claimed that it was "necessary to have the water dirty, with 

 mud, sand, or small pieces of debris for the eggs to fall upon; otherwise the eggs will 

 simply all stick together and quickly go moldy." While agreeing that the presence of 

 dirt is a positive advantage in the way that Tillyard suggests, the present author can 

 not agree that it is always "necessary." All the experiments hereinafter recorded were 

 made in clean water, and while the eggs usually did stick together, they did not mold 

 except in a single instance, and even then practically all of them hatched. However, 

 if the nymphs are to be used simply to stock the fishpond, some dirt and debris are 

 desirable, since then the conditions are more nearly natural. Similarly, when the 

 male accompanies the female during ovipositing, on being captured the female will 

 deposit her eggs freely in the tumbler or basin ; this applies to such species as Tramea and 

 Celithemis. 



Needham recorded a female Gomphus graslinellus captured while ovipositing, 

 from which he "obtained in a tumbler of water an immense number of eggs" (Need- 

 ham and Hart, 1901, p. 69). Also a female Gomphus externus, "captured in the weeds 



