DRAGONFUES AND DAMSELI^LIES IN PONDFISH CUIvTURE. 221 



had repeatedly seen ^^^schninae feeding upon gnats and mosquitoes in the late afternoon. 

 A specimen of Telephlebia godeffroyi was once observed flying round and round a small 

 bush at about 7 o'clock in the evening, when the mosquitoes were particularly trouble- 

 some. After 10 minutes it was captured and its mouth was found so full of mosquitoes 

 that it was unable to shut it. 



There must have been over a hundred all tightly packed into a black mass. I have frequently 

 seen JEschna brevistyla take gnats and mosquitoes in dozens while on the wing. There can be no doubt 

 that those dragonflies which fly late in the day are of great value in checking the spread of the various 

 objectionable Culicidse that are on the wing from just before sundown, 



Needham and Hart (1901, p. 29) make a similar statement: "The usefulness of the. 

 i^schnidae imagos, especially Anax junius, on account of the enormous quantities of 

 pestiferous gnats and mosquitoes which they destroy, puts them among the particular 

 friends of mankind." The Anax imago hunts after sunset, continues flying as long 

 as there is light enough to render its prey visible, and is probably the last dragonfly to go 

 to roost. In its search for food it frequently mounts high up in the air, sometimes dis- 

 appearing from sight in this manner. The male of L. luctuosa has similar habits, but does 

 not carry them quite as far. 



Dr. Lambom (1890) made an investigation to determine the practicability of the 

 artificial use of dragonflies for destroying mosquitoes and flies. While nothing very 

 practical in the way of artificial breeding was suggested, the investigation emphasized the 

 immense service rendered by dragonflies under natural conditions in keeping down these 

 pests. 



The members of the family Simuliidae are even greater pests than the mosquitoes. 

 One species, Simulium pecuarum, is known as the southern buffalo gnat and causes the 

 death of many mules and other domestic animals throughout the Mississippi Valley. 

 Another species, Simulium meridionale, is known as the turkey gnat, and it also infests 

 all kinds of domestic animals, especially the turkey. "Many cases of the death of human 

 beings from the bites of buffalo gnats have been reported, and some of them seem well 

 authenticated" (Needham, 1903, pt. 2, p. 343). However this may be, all the species 

 are bloodsuckers and intolerable pests, and anything which eats them is thereby dis- 

 tinctly beneficial. 



Consequently, even if it could be proved that nymphs had a fondness for young 

 fish, and that they were not themselves of any value as fish food, it would still seem 

 to the present author that the incessant warfare which they wage against gnats and mos- 

 quitoes ought to earn them a cordial welcome to every fishpond. It would certainly be 

 better for some of the fish to die than for the pond to become a breeding place for blood- 

 suckers and disease carriers. And if, in addition to this service, it can be shown, as has 

 been attem^pted, not only that the nymphs are harmless to the fish as long as they can 

 obtain other food (p. 206), but also that they themselves furnish one of the best of foods 

 for the growing fish (p. 205), they become practically a necessity if fish breeding is to be 

 carried on successfully. 



Another positive benefit to mankind is the wholesale destruction of house flies b}^ so 

 many of the odonates. It will be noted that this disease carrier appears as an article of 

 diet in nearly every one of the lists. iS)schna is frequently captured while devouring flies 

 on the screens and screen doors of dwelling houses and factories, and Anax has often been 

 reported from similar localities. A list has already been given of those species which 



