206 BULLETIN OF THE BUREAU OF FISHERIES. 
All the ponds of series D usually contain both Anax and A’schna nymphs, and 
several of them contain young fishes. When the ponds are drawn, as is done for each of 
them twice a year and sometimes oftener, the young fish and the nymphs, as well as all 
the other denizens of the pond, are brought into close contact. At such times crayfish, 
Dytiscus larve, and the like have been repeatedly observed catching and eating small 
fish, but no dragonfly nymph has been thus far seen attacking a fish. There is always an 
abundance of other food for them, and they evidently prefer it. In further proof of this 
18 Anax and A’schna nymphs were taken from ponds 7 and 9 on July 6, 1916, when they 
had attained their maximum size. Both ponds at that time contained an abundance of 
small fish, but no fish remains could be found in the alimentary canal of the nymphs. 
Hence when an Anax or Aischna nymph does prey upon fish it may well be because 
of a scarcity of other food. In evidence of this, Warren (1915, p. 35) has recorded a very 
interesting experiment. He placed 69 nymphs of Pantala flavescens and one of Anax 
junius in a small aquarium and gave them no food except one young fish. At the end 
of a week there were left 7 Pantala nymphs, the Anax nymph, and the little fish. As 
long as other food was present, therefore, the fish remained untouched. 
Furthermore, Warren examined the contents of the alimentary canal of 253 Anax 
and Pantala nymphs and found fish in only one of them. (See p.207.) Even there the 
remains were so doubtful that he placed a question mark after his identification of them. 
In a series of experiments made “‘ with the view of finding out how far the food range of 
the nymphs extended among the aquatic forms of life,” he placed various aquatic animals 
in the breeding jars and allowed the nymphs to eat them at their leisure. Among the 
forms thus eaten were several kinds of fish, which were common in the localities from 
whence the nymphs were obtained. Under natural conditions when other food was 
abundant the fish were not touched, but when brought into the laboratory and deprived 
of other food the nymphs ate the fish freely. 
Garman (1917, p. 441) gaveas one of the foods known to be eaten by damselfly nymphs 
very young fish. No authority was given for this statement, and inquiry has revealed 
that it was a mistake. We thus see that practically all the positive evidence shows that 
when an Anax or A’schna nymph does eat a young fish it is because of a scarcity of other 
food. Even if they do eat them occasionally they also eat enough Dytiscus larve, 
adult Corixas, Cypris, and crayfish to more than offset this. We must remember that 
it is only with reference to a very few of the largest species that any claims are 
made—2 dragonflies out of the 27 on the present list. The other 25 and all of the 
damselflies are admitted to be perfectly harmless so far as young fish are concerned. 
Amount oF Foop ConsuMED.—The nymphs are not only predatory and omnivorous, 
but they may fairly be called voracious. They gorge themselves to the full extent of 
their capacity, and the distended gizzard with its dark contents is often visible through 
the skin and always stands out prominently when the thorax is opened. Usually also 
the intestine behind the gizzard is filled out into a plump cylinder for 4 or 5 mm. with 
finely ground indigestible material, such as the mandibles of insect larve, fragments of 
snail shells, broken elytra, etc. 
There is a great difference in the amount of food consumed according to the condition 
of the nymph. Just after a molt the nymph is light in color, yellowish or greenish, and 
shows a characteristic color pattern very distinctly. As development progresses toward 
the next molt the color pattern gradually disappears, and the nymph becomes darker 
and darker until, in L. Juctuosa and E. simplicicollis, it turns to a uniform dark brown. 
