DRAGONFLIES AND DAMSELFLIKS IN PONDFISH CULTURE. 247 



our fresh- water game and food fish, while the larger species when fully grown are just 

 as toothsome to adult fish. The large percentage of nymphs in the food of fishes 

 from the Fairport ponds (table, p. 228) eiffectively answers the objection that odonates 

 rob the fishes of a part of their food. 



4. If the Anax, i^schna, and other large nymphs are preying upon the fish in any 

 given fishpond, this should be interpreted by the fish-culturist as evidence that the 

 supply of food in that pond is running low. His efforts can better be directed toward 

 replenishing the food supply than toward getting rid of the nymphs. On the other 

 hand, if they do not disturb the young fish the food supply is adequate, and they them- 

 selves will contribute to it in due time. They thus furnish a convenient means of 

 testing the food supply, since it is an easy matter to examine their stomachs and find 

 out what they are eating. 



5. Odonate imagos feed exclusively upon adult insects; their prey, like that of the 

 nymphs, sometimes includes insects that are beneficial, such as other odonates, honey- 

 bees, and hymenopterous parasites; but the bulk of their food is made up of insects 

 that are either positively injurious or negatively of no practical importance. Among 

 these may be mentioned gall flies, tsetse flies, plant lice, leaf hoppers, ants, and all 

 kinds of small moths and butterflies. They also confer an inestimable benefit upon 

 mankind by waging an incessant warfare upon house flies, mosquitoes, black flies, 

 and gnats. This one benefit alone far outweighs any harm they may do to the fish 

 and should earn for them a cordial welcome to every fishpona, present and future. 



6. Odonate imagos, like the nymphs, furnish good food for adult fishes, as is evi- 

 denced by finding them in the stomachs of various fishes taken under natural condi- 

 tions and from the fishponds. It has also been demonstrated by feeding live dragonfly 

 imagos to game fish in fishponds. 



7. Both nymphs and imagos are important factors in establishing a natural equi- 

 librium in the fauna and flora of the fishpond and its immediate environment. Other 

 things being equal, such an equilibrium contributes materially to success in fish culture, 

 and it can not be obtained without the presence of the nymphs and imagos. Inci- 

 dentally, if properly chosen, the imagos will add greatly to the attractiveness of the fish- 

 pond and its surroundings. 



8. Hence care should be taken that the pond is supplied with odonates, as well as 

 with fish; after the original stocking they can be left to take care of themselves. For 

 stocking purposes use common local species of dragonflies and damselflies; Anax, L. 

 pulchellay Plathemis, and the damselfly genera, Argia, Enallagma, and Lestes are so 

 cosmopolitan that they will make good stock almost anywhere in the United States. 

 Here again the odonates constitute a sort of visible pulse of the life of the pond ; so long 

 as they remain vigorous and healthy the pond life is probably moving along smoothly. 



9. Small breeding ponds along the margin of the fishpond from which the fish are 

 excluded will materially increase the supply of all aquatic insects, including the odonates. 

 If these are started in the spring or fall, the best odonate material to put into them will 

 be the nymphs. If they are started in the summer, they can be stocked more intelli- 

 gently by obtaining the eggs of desirable odonates and hatching them. 



10. Dragonflies v/ill not feed, nor mate, nor lay their eggs in captivity, but damsel- 

 flies are more susceptible, and eggs could probably be obtained from any common species. 

 If a female dragonfl}^ be caught v/hile ovipositing and held bv one pair of wings, leaving 



